SPI setup and AS1108 4 digit 7 segment decoder/driver


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  1. #1
    Join Date
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    Posts
    151

    Default SPI setup and AS1108 4 digit 7 segment decoder/driver

    Good Morning All-
    I have been bumping my head against this problem for a few days and I wondered if someone might steer me in the correct direction.
    I am trying to interface a AS1108 7 segment decoder driver to a 16F1527. I have stripped out all the other code normally used for debug like LEDs, etc.
    I have read/re-read both the SPI section for the 16F1527, printed it, marked it up, almost used it for toilet paper and tried to make sense of how to set up the registers correctly.
    Advice from other threads suggest using SHIFTOUT 1st to get it to work but the code listed looks as if it should work - but it doesn't.
    I thought I would ask this venerable forum for any insights before I use the slower SHIFTOUT.
    I have a logic analyzer (cheap) on the clock, data, and chip select pins and it looks like I am sending what I am supposed to so I think its in the timing, clock polarity, etc - but I can't seem to get it to work.
    I'm certain it is a simple thing, I just am in the forest now........and no trees apparently!
    I can't even get the 'H' to display!!! HELP!

    Code below for reference:

    Code:
    'SPI code for 4 digit 7-segment display board
    'The AS1108 contains four Digit-Registers and six control-registers. All registers are
    'selected using a 4-bit address word, and communication is done via the serial interface.
    'DIGIT Registers  These registers are realized with an on-chip 32-bit memory. Each digit can be controlled directly
    'without rewriting the whole register contents.
    'CONTROL Registers  These registers consist of decode mode, display intensity, number of scanned digits, shutdown,
    'display test and features selection registers.
    'Set for using PIC16F1527
    'Programmed using PicBasic Pro 3.0.1.4
    'Environment MCSP 5.0.0.2
    #CONFIG
            __config _CONFIG1, _FOSC_INTOSC & _WDTE_OFF & _PWRTE_ON & _MCLRE_ON & _CP_OFF & _BOREN_OFF & _CLKOUTEN_OFF & _IESO_OFF & _FCMEN_OFF 
            __config _CONFIG2, _WRT_OFF & _STVREN_ON & _LVP_OFF
    #ENDCONFIG
    
    '-----------------------------------------------------------------------------------------------------------------------
    'Define the oscillator and setup the INCLUDE files
        DEFINE  OSC 20					'20 MHz oscillator, however, use the internal for now 
    
    'OKAY, Lets set up the registers.....
        OSCCON=%01111010                                    '16 MHz internal clock
        ANSELA=%00000111                                    'Sets the 1st 3 bits as analog
        ANSELB=0                                            'Sets IO to DIGITAL
        ANSELD=0                                            'Sets IO to DIGITAL
        ANSELE=0                                            'Sets IO to DIGITAL
        ANSELF=0                                            'Sets IO to DIGITAL
        ANSELG=0                                            'Sets IO to DIGITAL
        WPUB=  %00000000                                    'DISABLES weak pullups on PORTB
        WPUD=  %11111111                                    'ENABLES weak pullups on PORTD
        WPUE=  %11111111                                    'ENABLES weak pullups on PORTE
        FVRCON=%11000011                                    'Voltage Ref is ENABLED at 4.096 volts
        ADCON0=%00000001                                     'Turns ON ADC, PORT A
        ADCON1=%11010011                                    'Right justifies, Fosc/16, Vref is connected to FVR internal
        CCP1CON=%00000000                                   'Turns OFF capture, compare, pwm
        CCP2CON=%00000000                                   'Turns OFF capture, compare, pwm    
        CCP3CON=%00000000                                   'Turns OFF capture, compare, pwm
        CCP4CON=%00000000                                   'Turns OFF capture, compare, pwm
        CCP5CON=%00000000                                   'Turns OFF capture, compare, pwm
        CCP6CON=%00000000                                   'Turns OFF capture, compare, pwm
        CCP7CON=%00000000                                   'Turns OFF capture, compare, pwm
        CCP8CON=%00000000                                   'Turns OFF capture, compare, pwm
        CCP9CON=%00000000                                   'Turns OFF capture, compare, pwm
        CCP10CON=%00000000                                  'Turns OFF capture, compare, pwm
        OPTION_REG=%01000111                                'TMR0 enabled, use internal (Fosc/4) Clock
                                                            'Low to High transition, use prescaler of 1:64
    '-----------------------------------------------------------------------------------------------------------------------
    'Direction registers
        TRISA = %10000111                                   'Set PORTA for bit7 is clk in, 4 led out, 3 A/D in
        TRISB = %11000000                                   'PORTB is OUTPUT, except B6&B7 
        TRISC = %10010000                                   'Set RC7 (RX), SDI, rest are outputs 
        TRISD = %11111111                                   'Set PORTD for high order INPUTS
        TRISE = %11111111                                   'Set PORTE for low order INPUTS
        TRISF = %00000000                                   'PORTF is low order OUTPUT  
        TRISG = %00100110                                   'PORTG is mixed    
    '----------------------------------------------------------------------------------------------------------------------- 
        WPUG.5=1                                                                              'Weak pullup in on MCLR    
    '-----------------------------------------------------------------------------------------------------------------------
    '****Here is my SPI Setup****
    'The AS1108 is selected by CS going low, after 16 clock cycles, shifted in when CS goes back high
        SSP1STAT.7 = 1                                      'SMP=0, sample phase
        SSP1STAT.6 = 1                                      'CKE=1, xmits on rising edge
        SSP1CON1.5=1                                        'enable SPI
        SSP1CON1.4=0                                        'CKP=0, clk idles low
        SSPCON.3=0                                          'bit 3 to 0 indicate clock speed. bit 0 set means clock = OSC/16 = 1.25 MHz @ 20MHz
        SSPCON.2=0
        SSPCON.1=0
        SSPCON.0=1
        PIR1.3 = 0                                          'Clear the buffer status. 
    
    '-----------------------------------------------------------------------------------------------------------------------    
    'Additional I/O Definitions
             as1108sel         var  PORTC.2
    
    
    '-----------------------------------------------------------------------------------------------------------------------
    'Vars
             SPIin             VAR WORD                                                        'DATA back from device
             SPIout            VAR WORD                                                        'DATA to the device        
            
    
    '-----------------------------------------------------------------------------------------------------------------------
    'AS1108 Data Frame structor 
    'D15 D14 D13 D12 D11  D10  D9  D8   D7 D6 D5 D4 D3 D2 D1 D0 
    'X   X    X   X  Register Address   MSB------Data--------LSB 
    '----------------------------------------------------------- 
             
    'Register Address 
    '                   Register Address Map
    'Register       HEX Code                Address         
    '                               D15:D12 D11 D10 D9 D8
    'No-Op              0xX0            X   0   0   0   0 
    'Digit 0            0xX1            X   0   0   0   1
    'Digit 1            0xX2            X   0   0   1   0
    'Digit 2            0xX3            X   0   0   1   1
    'Digit 3            0xX4            X   0   1   0   0
    'Decode-Mode        0xX9            X   1   0   0   1
    'Intensity Control  0xXA            X   1   0   1   0
    'Scan Limit         0xXB            X   1   0   1   1
    'Shutdown           0xXC            X   1   1   0   0
    'N/A                0xXD            X   1   1   0   1
    'Feature            0xXE            X   1   1   1   0
    'Display Test       0xXF            X   1   1   1   1
    
    
            No_Op               con $00                                            'not used for 1 Chip AS1108 
            Digit_1             con $01  
            Digit_2             con $02  
            Digit_3             con $03  
            Digit_4             con $04  
            Decode_Mode         con $09  
            Intensity_Control   con $0A  
            Scan_Limit          con $0B  
            Shutdown            con $0C  
            N_A                 con $0D    
            Feature             con $0E    
            Display_Test        con $0F 
    
    
    
    'Decode Enable Register (0xX9)
    'The Decode Enable Register sets the decode mode. BCD/HEX decoding (either BCD code  characters 0:9, E, H, L,
    'P, and -, or HEX code  characters 0:9 and A:F) is selected by bit D2 of the Feature Register. The Decode
    'Enable Register is used to select the decode mode or no-decode for each digit. Each bit in the Decode Enable Register
    'corresponds to its respective display digit (i.e., bit D0 corresponds to digit 0, bit D1 corresponds to digit 1 and so
    'on). 
    
    'Note: A logic high enables decoding and a logic low bypasses the decoder altogether.
    
    'When decode mode is used, the decoder looks only at the lower-nibble (bits D3:D0) of the data in the Digit-Registers,
    'disregarding bits D6:D4. Bit D7 sets the decimal point (SEG DP) independent of the decoder and is positive logic (bit
    'D7 = 1 turns the decimal point on). 
    'When no-decode mode is selected, data bits D7:D0 of the Digit-Registers correspond to the segment lines of the
    'AS1108.
    
    'Decode Mode                                        HEX Code                        Register Data
    '                                                                           D7  D6  D5  D4  D3  D2  D1  D0
    'No decode for digits 3:0                               0x00                X   X   X   X   0   0   0   0
    'Code-B/HEX decode for digit 0. No decode for digits 3:1 0x01               X   X   X   X   0   0   0   1
    'Code-B/HEX decode for digits 3:0                       0xFF                X   X   X   X   1   1   1   1
    
    '                               Code-B Font
    '7-Segment  Register Data                   On Segments = 1
    '           D7  D6:D4   D3  D2  D1  D0  DP  A B C D E F G
    '   0            X      0   0   0   0       1 1 1 1 1 1 0
    '   1           X       0   0   0   1       0 1 1 0 0 0 0
    '   2           X       0   0   1   0       1 1 0 1 1 0 1
    '   3           X       0   0   1   1       1 1 1 1 0 0 1
    '   4           X       0   1   0   0       0 1 1 0 0 1 1
    '   5           X       0   1   0   1       1 0 1 1 0 1 1
    '   6           X       0   1   1   0       1 0 1 1 1 1 1
    '   7           X       0   1   1   1       1 1 1 0 0 0 0
    '   8           X       1   0   0   0       1 1 1 1 1 1 1
    '   9           X       1   0   0   1       1 1 1 1 0 1 1
    '   -           X       1   0   1   0       0 0 0 0 0 0 1
    '   E           X       1   0   1   1       1 0 0 1 1 1 1
    '   H           X       1   1   0   0       0 1 1 0 1 1 1
    '   L           X       1   1   0   1       0 0 0 1 1 1 0
    '   P           X       1   1   1   0       1 1 0 0 1 1 1
    'Blank          X       1   1   1   1       0 0 0 0 0 0 0
    ' The decimal point is enabled by setting bit D7 = 1.
    
    '                               HEX Font
    '7-Segment  Register Data                   On Segments = 1
    '           D7  D6:D4   D3  D2  D1  D0  DP  A B C D E F G
    '   0           X       0   0   0   0       1 1 1 1 1 1 0
    '   1           X       0   0   0   1       0 1 1 0 0 0 0
    '   2           X       0   0   1   0       1 1 0 1 1 0 1
    '   3           X       0   0   1   1       1 1 1 1 0 0 1
    '   4           X       0   1   0   0       0 1 1 0 0 1 1
    '   5           X       0   1   0   1       1 0 1 1 0 1 1
    '   6           X       0   1   1   0       1 0 1 1 1 1 1
    '   7           X       0   1   1   1       1 1 1 0 0 0 0
    '   8           X       1   0   0   0       1 1 1 1 1 1 1
    '   9           X       1   0   0   1       1 1 1 1 0 1 1
    '   A           X       1   0   1   0       1 1 1 0 1 1 1
    '   b           X       1   0   1   1       0 0 1 1 1 1 1
    '   C           X       1   1   0   0       1 0 0 1 1 1 0
    '   d           X       1   1   0   1       0 1 1 1 1 0 1
    '   E           X       1   1   1   0       1 0 0 1 1 1 1
    '   F           X       1   1   1   1       1 0 0 0 1 1 1
    ' The decimal point is enabled by setting bit D7 = 1.
    
    
    'Decode_Mode (0x09) 
            decode_mode_1       con 00                                            'No decode for digits 3:0 
            decode_mode_2       con 01                                            'Code-B/HEX decode for digit 0. No decode for digits 3:1 
            decode_mode_3       con $FF                                           'Code-B/HEX decode for digits 3:0 
    
    'Display-Test Register (0xXF)
    'The AS1108 can operate in two modes: normal mode and display test mode. In display test mode all LEDs are
    'switched on at maximum brightness (duty cycle is 15/16). The device remains in display-test mode until the Display-
    'Test Register is set for normal operation.
    
    'Display_Test (0x0F) 
            display_test_mode_1 con 00                                            'Normal Operation 
            display_test_mode_2 con 01                                            'Display Test Mode 
            
    
    'Intensity Control Register (0xXA)
    'The brightness of the display can be controlled by digital means using the Intensity Control Register and by analog
    'means using RSET.
    'Display brightness is controlled by an integrated pulse-width modulator which is controlled by the lower-nibble of the
    'Intensity Control Register. The modulator scales the average segment-current in 16 steps from a maximum of 31/32
    'down to 1/32 of the peak current set by RSET.
    
    'Intensity Control Register (0x0A) have 16 Level brightness 
            intensity_level_0   con 00                                            '1/32 (min on) 0xX0  
            intensity_level_1   con 01                                            '3/32 0xX1 
            intensity_level_2   con 02                                            '5/32 0xX2  
            intensity_level_3   con 03                                            '7/32 0xX3  
            intensity_level_4   con 04                                            '9/32 0xX4 
            intensity_level_5   con 05                                            '11/32 0xX5  
            intensity_level_6   con 06                                            '13/32 0xX6 
            intensity_level_7   con 07                                            '15/32 0xX7  
            intensity_level_8   con 08                                            '17/32 0xX8  
            intensity_level_9   con 09                                            '19/32 0xX9  
            intensity_level_10  con $0A                                            '21/32 0xXA  
            intensity_level_11  con $0B                                            '23/32 0xXB  
            intensity_level_12  con $0C                                            '25/32 0xXC  
            intensity_level_13  con $0D                                            '27/32 0xXD  
            intensity_level_14  con $0E                                            '29/32 0xXE 
            intensity_level_15  con $0F                                            '31/32 (max on) 0xXF 
            
    'Scan-Limit Register (0x0B)
    'The Scan-Limit Register controls which of the digits are to be displayed. When all 4 digits are to be displayed, the
    'update frequency is typically 1600Hz. If the number of digits displayed is reduced, the update frequency is increased.
    'The frequency can be calculated using 8fOSC/N, where N is the number of digits. Since the number of displayed digits
    'influences the brightness, RSET should be adjusted accordingly. 
    'Note: To avoid differences in brightness this register should not be used to blank parts of the display (leading zeros).
    
    'Scan-Limit Register (0x0B) 
    
            Scan_Limit_mode_1   con 00                                            'Display digit  0 only    
            Scan_Limit_mode_2   con 01                                            'Display digits 0:1    
            Scan_Limit_mode_3   con 02                                            'Display digits 0:2      
            Scan_Limit_mode_4   con 03                                            'Display digits 0:3  
            
    'Feature Register (0xXE)
    'The Feature Register is used for switching the device into external clock mode, applying an external reset, selecting
    'code-B or HEX decoding, enabling or disabling blinking, enabling or disabling the SPI-compatible interface, setting the
    'blinking rate, and resetting the blink timing.
    
    'Feature Register Summary
    'D7     D6      D5          D4      D3          D2              D1      D0
    'blink_ sync    blink_      Blink_  spi_en      decode_sel   reg_res    clk_en
    'start          freq_sel    en 
    
    
    'Bit    Bit Name        Default     Access                     Bit Description
    'D0     clk_en              0       R/W         External clock select.
    '                                               0 = Internal oscillator is used for system clock.
    '                                               1 = Pin CLK of the serial interface operates as system clock input.
    'D1     reg_res             0       R/W         Resets all control registers except the Feature Register.
    '                                               0 = Reset Disabled. Normal operation.
    '                                               1 = All control registers are reset to default state (except the Feature
    '                                               Register) identically after power-up.
    '                                               Note: The Digit Registers maintain their data.
    'D2     decode_sel          0       R/W         Selects display decoding.
    '                                               0 = Enable Code-B decoding 
    '                                               1 = Enable HEX decoding 
    'D3     spi_en              0       R/W         Enables the SPI-compatible interface.
    '                                               0 = Disable SPI-compatible interface.
    '                                               1 = Enable the SPI-compatible interface.
    'D4     blink_en            0       R/W         Enables blinking.
    '                                               0 = Disable blinking.
    '                                               1 = Enable blinking.
    'D5     blink_freq_sel      0       R/W         Sets blink with low frequency (with the internal oscillator enabled):
    '                                               0 = Blink period typically is 1 second (0.5s on, 0.5s off).
    '                                               1 = Blink period is 2 seconds (1s on, 1s off).
    'D6     sync                0       R/W         Synchronizes blinking on the rising edge of pin LOAD/CSN. The
    '                                               multiplex and blink timing counter is cleared on the rising edge of pin
    '                                               LOAD/CSN. By setting this bit in multiple AS1108 devices, the blink
    '                                               timing can be synchronized across all the devices.
    'D7     blink_start         0       R/W         Start Blinking with display enabled phase. When bit D4 (blink_en) is set,
    '                                               bit D7 determines how blinking starts.
    '                                               0 = Blinking starts with the display turned off.
    '                                               1 = Blinking starts with the display turned on.
    
            SysFeature          con %00001101                                       'HEX decoding and external clock is clock-in
            
    'Setup to actually start writing to display controller
    ' Use Code-B, Normal operation w/ feature reg unchanged, Normal operation, Code-B hex for digits 3:0, Max intensity, display all 4 digits.         
            
        goto init                                            'Jumps around subs
        
    '-----------------------------------------------------------------------------------------------------------------------
    'Subs
    '**********SPI SEND******************
    Send_SPIData:
        as1108sel=0                                                             'Select the chip
        SSP1BUF = SPIout.HIGHBYTE
        while !PIR1.3 : wend
    '    pauseus 1
        PIR1.3=0                                                                'Reset the flag
        SSP1CON1.7=0                                                            'Clear collision bit
        SSP1BUF = SPIout.LOWByte
        while !PIR1.3 : wend
    '    pauseus 1
        PIR1.3 = 0                                                              'Reset the flag
        SSP1CON1.7=0                                                            'Clear collision bit
        as1108sel=1                                                             'Deselect the chip
        return 
    
    '-----------------------------------------------------------------------------------------------------------------------
    
    
    init:   
        AS1108SEL=1
        SSP1CON1.7=0                                                            'Clear collision bit
        PIR1.3=0                                                                'Reset the flag
    
    'Sets up the 4 digit display 
        SPIout.highbyte=feature
        SPIout.lowbyte=sysfeature                                               'Sets up the feature register
        gosub Send_SPIData
    '    pauseus 2
        spiout.highbyte=Scan_Limit
        SPIout.lowbyte=Scan_Limit_mode_4                                       'Uses all 4 digits
        gosub Send_SPIData
    '    pauseus 2
        spiout.highbyte=Intensity_Control
        SPIout.lowbyte=intensity_level_11                                      'Intensity set to 11
        gosub Send_SPIData
    '    pauseus 2
        spiout.highbyte=Decode_Mode
        SPIout.lowbyte=Decode_Mode_3                                           'Hex decode for all 4 difits
        gosub Send_SPIData
    '    pauseus 2
    'Disply HELP as a signon.....
        spiout.highbyte=Digit_4
        SPIout.lowbyte=$C                                                      'Disp 'H'
        gosub Send_SPIData
    '    pauseus 2
    '    spiout.highbyte=Digit_3
    '    SPIout.lowbyte=$B                                                      'Disp 'E'
    '    gosub Send_SPIData
    '    pauseus 2
    '    spiout.highbyte=Digit_2
    '    SPIout.lowbyte=$D                                                      'Disp 'L'
    '    gosub Send_SPIData
    '    pauseus 2
    '    spiout.highbyte=Digit_1
    '    SPIout.lowbyte=$E                                                      'Disp 'P'
    '    gosub Send_SPIData
    '    pauseus 2
        
        stop                                                                    'See if it works......
    "If we knew what we were doing, it wouldn't be called research"
    - Albert Einstein

  2. #2

    Default Re: SPI setup and AS1108 4 digit 7 segment decoder/driver

    I think you have CKE wrong, you've set clock to idle low so you want CKE = 0 "Transmit occurs on transition from Idle to active clock state".

    George

  3. #3
    Join Date
    Sep 2007
    Location
    Waco, Texas
    Posts
    151

    Default Re: SPI setup and AS1108 4 digit 7 segment decoder/driver

    Thanks George, I'm pretty sure I have tried that but I will look at that once again.
    I just now had a thought about the clock, I may be misguided in what the sheet says it really does.........
    Still hangin' in here......
    I'll chase another rabbit and see where it leads......
    "If we knew what we were doing, it wouldn't be called research"
    - Albert Einstein

  4. #4

    Default Re: SPI setup and AS1108 4 digit 7 segment decoder/driver

    Not wishing to labor the point but (ah, there's always a but) looking at this diagram from the datasheet

    Clock is idle low and data is clocked by idle to active clock. Sample (assuming you're reading as well) seems to be either but I guess preferably middle.

    George

    JIC use your analyzer to ensure that you're sending 16 bits between CSN low and CSN high
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    Last edited by towlerg; - 5th November 2014 at 22:14. Reason: old and stupid

  5. #5
    Join Date
    Sep 2007
    Location
    Waco, Texas
    Posts
    151

    Default Re: SPI setup and AS1108 4 digit 7 segment decoder/driver

    I found the problem!
    Stupid me, I 'thought' the clock in the FEATURE reg was to clock the entire system, well, it turns out it uses 2 clocks apparently. System clock to clock data in, then an internal clock to actually clock into the internal registers.
    Also, upon carefully re-reading the data (with an Adult Beverage) I found that the chip has to be told to come out of SHUTDOWN, well the working code is below for others to use.

    You CAN use the MSSI for SPI, as has been said before, you do have to be careful and read the manual apparently 23 times .
    George- The chip works with SMP=0, CKE=1, CKP=0

    Working code below:
    Code:
    'SPI code for 4 digit 7-segment display board
    'The AS1108 contains four Digit-Registers and six control-registers. All registers are
    'selected using a 4-bit address word, and communication is done via the serial interface.
    'DIGIT Registers  These registers are realized with an on-chip 32-bit memory. Each digit can be controlled directly
    'without rewriting the whole register contents.
    'CONTROL Registers  These registers consist of decode mode, display intensity, number of scanned digits, shutdown,
    'display test and features selection registers.
    'Set for using PIC16F1527
    'Programmed using PicBasic Pro 3.0.1.4
    'Environment MCSP 5.0.0.2
    #CONFIG
            __config _CONFIG1, _FOSC_ECH & _WDTE_OFF & _PWRTE_ON & _MCLRE_ON & _CP_OFF & _BOREN_OFF & _CLKOUTEN_OFF & _IESO_OFF & _FCMEN_OFF 
            __config _CONFIG2, _WRT_OFF & _STVREN_ON & _LVP_OFF
    #ENDCONFIG
    
    '-----------------------------------------------------------------------------------------------------------------------
    'Define the oscillator and setup the INCLUDE files
        DEFINE  OSC 20					'20 MHz oscillator 
    
    'OKAY, Lets set up the registers.....
        OSCCON=%01111010                                    '16 MHz internal clock
        ANSELA=%00000111                                    'Sets the 1st 3 bits as analog
        ANSELB=0                                            'Sets IO to DIGITAL
        ANSELD=0                                            'Sets IO to DIGITAL
        ANSELE=0                                            'Sets IO to DIGITAL
        ANSELF=0                                            'Sets IO to DIGITAL
        ANSELG=0                                            'Sets IO to DIGITAL
        WPUB=  %00000000                                    'DISABLES weak pullups on PORTB
        WPUD=  %11111111                                    'ENABLES weak pullups on PORTD
        WPUE=  %11111111                                    'ENABLES weak pullups on PORTE
        FVRCON=%11000011                                    'Voltage Ref is ENABLED at 4.096 volts
        ADCON0=%00000001                                     'Turns ON ADC, PORT A
        ADCON1=%11010011                                    'Right justifies, Fosc/16, Vref is connected to FVR internal
        CCP1CON=%00000000                                   'Turns OFF capture, compare, pwm
        CCP2CON=%00000000                                   'Turns OFF capture, compare, pwm    
        CCP3CON=%00000000                                   'Turns OFF capture, compare, pwm
        CCP4CON=%00000000                                   'Turns OFF capture, compare, pwm
        CCP5CON=%00000000                                   'Turns OFF capture, compare, pwm
        CCP6CON=%00000000                                   'Turns OFF capture, compare, pwm
        CCP7CON=%00000000                                   'Turns OFF capture, compare, pwm
        CCP8CON=%00000000                                   'Turns OFF capture, compare, pwm
        CCP9CON=%00000000                                   'Turns OFF capture, compare, pwm
        CCP10CON=%00000000                                  'Turns OFF capture, compare, pwm
        OPTION_REG=%01000111                                'TMR0 enabled, use internal (Fosc/4) Clock
                                                            'Low to High transition, use prescaler of 1:64
    '-----------------------------------------------------------------------------------------------------------------------
    'Direction registers
        TRISA = %10000111                                   'Set PORTA for bit7 is clk in, 4 led out, 3 A/D in
        TRISB = %11000000                                   'PORTB is OUTPUT, except B6&B7 
        TRISC = %10010000                                   'Set RC7 (RX), SDI, rest are outputs 
        TRISD = %11111111                                   'Set PORTD for high order INPUTS
        TRISE = %11111111                                   'Set PORTE for low order INPUTS
        TRISF = %00000000                                   'PORTF is low order OUTPUT  
        TRISG = %00100110                                   'PORTG is mixed    
    '----------------------------------------------------------------------------------------------------------------------- 
        WPUG.5=1                                                                              'Weak pullup in on MCLR    
    '-----------------------------------------------------------------------------------------------------------------------
    '****Here is my SPI Setup****
    'The AS1108 is selected by CS going low, after 16 clock cycles, shifted in when CS goes back high
        SSP1STAT.7 = 0                                      'SMP=0, sample phase
        SSP1STAT.6 = 1                                      'CKE=1, xmits on rising edge
        SSP1CON1.5=1                                        'enable SPI
        SSP1CON1.4=0                                        'CKP=0, clk idles low
        SSPCON.3=0                                          'bit 3 to 0 indicate clock speed. bit 0 set means clock = OSC/16 = 1.25 MHz @ 20MHz
        SSPCON.2=0
        SSPCON.1=0
        SSPCON.0=1
        PIR1.3 = 0                                          'Clear the buffer status. 
    'Found this to help out w/ low 4 bits of SSPCON:
    '0000 = SPI Master mode, clock Fosc/4
    '0001 = SPI Master mode, clock = Fosc/16
    '0010 = SPI Master mode, clock = Fosc/64
    '0011 = SPI Master mode, clock = TMR2 output/2
    '0100 = SPI Slave mode, clock = SCK pin. SS pin control enabled
    '0101 = SPI Slave mode, clock = SCK pin. SS pin control disabled. SS can be used as I/O pin.
    '0110 = I2C Slave mode, 7-bit address
    '0111 = I2C Slave mode, 10-bit address
    '1011 = I2C Firmware Controlled Master mode (slave IDLE)
    '1110 = I2C Slave mode, 7-bit address with START and STOP bit interrupts enabled 
    '1111 = I2C Slave mode, 10-bit address with START and STOP bit interrupts enabled
    '-----------------------------------------------------------------------------------------------------------------------    
    'Additional I/O Definitions
             as1108sel         var  PORTC.2
    
    
    '-----------------------------------------------------------------------------------------------------------------------
    'Vars
             SPIin             VAR WORD                                                        'DATA back from device
             SPIout            VAR WORD                                                        'DATA to the device        
            
    
    '-----------------------------------------------------------------------------------------------------------------------
    'AS1108 Data Frame structor 
    'D15 D14 D13 D12 D11  D10  D9  D8   D7 D6 D5 D4 D3 D2 D1 D0 
    'X   X    X   X  Register Address   MSB------Data--------LSB 
    '----------------------------------------------------------- 
             
    'Register Address 
    '                   Register Address Map
    'Register       HEX Code                Address         
    '                               D15:D12 D11 D10 D9 D8
    'No-Op              0xX0            X   0   0   0   0 
    'Digit 0            0xX1            X   0   0   0   1
    'Digit 1            0xX2            X   0   0   1   0
    'Digit 2            0xX3            X   0   0   1   1
    'Digit 3            0xX4            X   0   1   0   0
    'Decode-Mode        0xX9            X   1   0   0   1
    'Intensity Control  0xXA            X   1   0   1   0
    'Scan Limit         0xXB            X   1   0   1   1
    'Shutdown           0xXC            X   1   1   0   0
    'N/A                0xXD            X   1   1   0   1
    'Feature            0xXE            X   1   1   1   0
    'Display Test       0xXF            X   1   1   1   1
    
    
            No_Op               con $00                                            'not used for 1 Chip AS1108 
            Digit_1             con $01  
            Digit_2             con $02  
            Digit_3             con $03  
            Digit_4             con $04  
            Decode_Mode         con $09  
            Intensity_Control   con $0A  
            Scan_Limit          con $0B  
            Shutdown            con $0C  
            N_A                 con $0D    
            Feature             con $0E    
            Display_Test        con $0F 
    
    
    
    'Decode Enable Register (0xX9)
    'The Decode Enable Register sets the decode mode. BCD/HEX decoding (either BCD code  characters 0:9, E, H, L,
    'P, and -, or HEX code  characters 0:9 and A:F) is selected by bit D2 of the Feature Register. The Decode
    'Enable Register is used to select the decode mode or no-decode for each digit. Each bit in the Decode Enable Register
    'corresponds to its respective display digit (i.e., bit D0 corresponds to digit 0, bit D1 corresponds to digit 1 and so
    'on). 
    
    'Note: A logic high enables decoding and a logic low bypasses the decoder altogether.
    
    'When decode mode is used, the decoder looks only at the lower-nibble (bits D3:D0) of the data in the Digit-Registers,
    'disregarding bits D6:D4. Bit D7 sets the decimal point (SEG DP) independent of the decoder and is positive logic (bit
    'D7 = 1 turns the decimal point on). 
    'When no-decode mode is selected, data bits D7:D0 of the Digit-Registers correspond to the segment lines of the
    'AS1108.
    
    'Decode Mode                                        HEX Code                        Register Data
    '                                                                           D7  D6  D5  D4  D3  D2  D1  D0
    'No decode for digits 3:0                               0x00                X   X   X   X   0   0   0   0
    'Code-B/HEX decode for digit 0. No decode for digits 3:1 0x01               X   X   X   X   0   0   0   1
    'Code-B/HEX decode for digits 3:0                       0xFF                X   X   X   X   1   1   1   1
    
    '                               Code-B Font
    '7-Segment  Register Data                   On Segments = 1
    '           D7  D6:D4   D3  D2  D1  D0  DP  A B C D E F G
    '   0            X      0   0   0   0       1 1 1 1 1 1 0
    '   1           X       0   0   0   1       0 1 1 0 0 0 0
    '   2           X       0   0   1   0       1 1 0 1 1 0 1
    '   3           X       0   0   1   1       1 1 1 1 0 0 1
    '   4           X       0   1   0   0       0 1 1 0 0 1 1
    '   5           X       0   1   0   1       1 0 1 1 0 1 1
    '   6           X       0   1   1   0       1 0 1 1 1 1 1
    '   7           X       0   1   1   1       1 1 1 0 0 0 0
    '   8           X       1   0   0   0       1 1 1 1 1 1 1
    '   9           X       1   0   0   1       1 1 1 1 0 1 1
    '   -           X       1   0   1   0       0 0 0 0 0 0 1
    '   E           X       1   0   1   1       1 0 0 1 1 1 1
    '   H           X       1   1   0   0       0 1 1 0 1 1 1
    '   L           X       1   1   0   1       0 0 0 1 1 1 0
    '   P           X       1   1   1   0       1 1 0 0 1 1 1
    'Blank          X       1   1   1   1       0 0 0 0 0 0 0
    ' The decimal point is enabled by setting bit D7 = 1.
    
    '                               HEX Font
    '7-Segment  Register Data                   On Segments = 1
    '           D7  D6:D4   D3  D2  D1  D0  DP  A B C D E F G
    '   0           X       0   0   0   0       1 1 1 1 1 1 0
    '   1           X       0   0   0   1       0 1 1 0 0 0 0
    '   2           X       0   0   1   0       1 1 0 1 1 0 1
    '   3           X       0   0   1   1       1 1 1 1 0 0 1
    '   4           X       0   1   0   0       0 1 1 0 0 1 1
    '   5           X       0   1   0   1       1 0 1 1 0 1 1
    '   6           X       0   1   1   0       1 0 1 1 1 1 1
    '   7           X       0   1   1   1       1 1 1 0 0 0 0
    '   8           X       1   0   0   0       1 1 1 1 1 1 1
    '   9           X       1   0   0   1       1 1 1 1 0 1 1
    '   A           X       1   0   1   0       1 1 1 0 1 1 1
    '   b           X       1   0   1   1       0 0 1 1 1 1 1
    '   C           X       1   1   0   0       1 0 0 1 1 1 0
    '   d           X       1   1   0   1       0 1 1 1 1 0 1
    '   E           X       1   1   1   0       1 0 0 1 1 1 1
    '   F           X       1   1   1   1       1 0 0 0 1 1 1
    ' The decimal point is enabled by setting bit D7 = 1.
    
    
    'Decode_Mode (0x09) 
            decode_mode_1       con 00                                            'No decode for digits 3:0 
            decode_mode_2       con 01                                            'Code-B/HEX decode for digit 0. No decode for digits 3:1 
            decode_mode_3       con $FF                                           'Code-B/HEX decode for digits 3:0 
    
    'Display-Test Register (0xXF)
    'The AS1108 can operate in two modes: normal mode and display test mode. In display test mode all LEDs are
    'switched on at maximum brightness (duty cycle is 15/16). The device remains in display-test mode until the Display-
    'Test Register is set for normal operation.
    
    'Display_Test (0x0F) 
            display_test_mode_1 con 00                                            'Normal Operation 
            display_test_mode_2 con 01                                            'Display Test Mode 
            
    
    'Intensity Control Register (0xXA)
    'The brightness of the display can be controlled by digital means using the Intensity Control Register and by analog
    'means using RSET.
    'Display brightness is controlled by an integrated pulse-width modulator which is controlled by the lower-nibble of the
    'Intensity Control Register. The modulator scales the average segment-current in 16 steps from a maximum of 31/32
    'down to 1/32 of the peak current set by RSET.
    
    'Intensity Control Register (0x0A) have 16 Level brightness 
            intensity_level_0   con 00                                            '1/32 (min on) 0xX0  
            intensity_level_1   con 01                                            '3/32 0xX1 
            intensity_level_2   con 02                                            '5/32 0xX2  
            intensity_level_3   con 03                                            '7/32 0xX3  
            intensity_level_4   con 04                                            '9/32 0xX4 
            intensity_level_5   con 05                                            '11/32 0xX5  
            intensity_level_6   con 06                                            '13/32 0xX6 
            intensity_level_7   con 07                                            '15/32 0xX7  
            intensity_level_8   con 08                                            '17/32 0xX8  
            intensity_level_9   con 09                                            '19/32 0xX9  
            intensity_level_10  con $0A                                            '21/32 0xXA  
            intensity_level_11  con $0B                                            '23/32 0xXB  
            intensity_level_12  con $0C                                            '25/32 0xXC  
            intensity_level_13  con $0D                                            '27/32 0xXD  
            intensity_level_14  con $0E                                            '29/32 0xXE 
            intensity_level_15  con $0F                                            '31/32 (max on) 0xXF 
            
    'Scan-Limit Register (0x0B)
    'The Scan-Limit Register controls which of the digits are to be displayed. When all 4 digits are to be displayed, the
    'update frequency is typically 1600Hz. If the number of digits displayed is reduced, the update frequency is increased.
    'The frequency can be calculated using 8fOSC/N, where N is the number of digits. Since the number of displayed digits
    'influences the brightness, RSET should be adjusted accordingly. 
    'Note: To avoid differences in brightness this register should not be used to blank parts of the display (leading zeros).
    
    'Scan-Limit Register (0x0B) 
    
            Scan_Limit_mode_1   con 00                                            'Display digit  0 only    
            Scan_Limit_mode_2   con 01                                            'Display digits 0:1    
            Scan_Limit_mode_3   con 02                                            'Display digits 0:2      
            Scan_Limit_mode_4   con 03                                            'Display digits 0:3  
            
    'Feature Register (0xXE)
    'The Feature Register is used for switching the device into external clock mode, applying an external reset, selecting
    'code-B or HEX decoding, enabling or disabling blinking, enabling or disabling the SPI-compatible interface, setting the
    'blinking rate, and resetting the blink timing.
    
    'Feature Register Summary
    'D7     D6      D5          D4      D3          D2              D1      D0
    'blink_ sync    blink_      Blink_  spi_en      decode_sel   reg_res    clk_en
    'start          freq_sel    en 
    
    
    'Bit    Bit Name        Default     Access                     Bit Description
    'D0     clk_en              0       R/W         External clock select.
    '                                               0 = Internal oscillator is used for system clock.
    '                                               1 = Pin CLK of the serial interface operates as system clock input.
    'D1     reg_res             0       R/W         Resets all control registers except the Feature Register.
    '                                               0 = Reset Disabled. Normal operation.
    '                                               1 = All control registers are reset to default state (except the Feature
    '                                               Register) identically after power-up.
    '                                               Note: The Digit Registers maintain their data.
    'D2     decode_sel          0       R/W         Selects display decoding.
    '                                               0 = Enable Code-B decoding 
    '                                               1 = Enable HEX decoding 
    'D3     spi_en              0       R/W         Enables the SPI-compatible interface.
    '                                               0 = Disable SPI-compatible interface.
    '                                               1 = Enable the SPI-compatible interface.
    'D4     blink_en            0       R/W         Enables blinking.
    '                                               0 = Disable blinking.
    '                                               1 = Enable blinking.
    'D5     blink_freq_sel      0       R/W         Sets blink with low frequency (with the internal oscillator enabled):
    '                                               0 = Blink period typically is 1 second (0.5s on, 0.5s off).
    '                                               1 = Blink period is 2 seconds (1s on, 1s off).
    'D6     sync                0       R/W         Synchronizes blinking on the rising edge of pin LOAD/CSN. The
    '                                               multiplex and blink timing counter is cleared on the rising edge of pin
    '                                               LOAD/CSN. By setting this bit in multiple AS1108 devices, the blink
    '                                               timing can be synchronized across all the devices.
    'D7     blink_start         0       R/W         Start Blinking with display enabled phase. When bit D4 (blink_en) is set,
    '                                               bit D7 determines how blinking starts.
    '                                               0 = Blinking starts with the display turned off.
    '                                               1 = Blinking starts with the display turned on.
    
            SysFeature          con %00001000       'Code-B decoding and internal clock (this was the big deal, INTERNAL CLOCK!)
            
    'Setup to actually start writing to display controller
    ' Use Code-B, Normal operation w/ feature reg unchanged, Normal operation, Code-B hex for digits 3:0, Max intensity, display all 4 digits.         
            
        goto init                                            'Jumps around subs
        
    '-----------------------------------------------------------------------------------------------------------------------
    'Subs
    '**********SPI SEND******************
    Send_SPIData:
        as1108sel=0                                                             'Select the chip
        SSP1BUF = SPIout.HIGHBYTE
        while !PIR1.3 : wend
    '    pauseus 1
        PIR1.3=0                                                                'Reset the flag
        SSP1CON1.7=0                                                            'Clear collision bit
        SSP1BUF = SPIout.LOWByte
        while !PIR1.3 : wend
    '    pauseus 1
        PIR1.3 = 0                                                              'Reset the flag
        SSP1CON1.7=0                                                            'Clear collision bit
        as1108sel=1                                                             'Deselect the chip
        return 
    
    '-----------------------------------------------------------------------------------------------------------------------
    
    
    init:   
        AS1108SEL=1
        SSP1CON1.7=0                                                            'Clear collision bit
        PIR1.3=0                                                                'Reset the flag
    
    'Sets up the 4 digit display 
        SPIout.highbyte=Shutdown
        SPIout.lowbyte=$01                                                      'Sets up normal op out of shutdown
        gosub Send_SPIData
    '    pauseus 2
        SPIout.highbyte=feature
        SPIout.lowbyte=sysfeature                                               'Sets up the feature register
        gosub Send_SPIData
    '    pauseus 2
        spiout.highbyte=Scan_Limit
        SPIout.lowbyte=$03                                                     'Uses all 4 digits
        gosub Send_SPIData
    '    pauseus 2
        spiout.highbyte=Intensity_Control
        SPIout.lowbyte=intensity_level_15                                      'Intensity set to 15, highest
        gosub Send_SPIData
    '    pauseus 2
        spiout.highbyte=Decode_Mode
        SPIout.lowbyte=Decode_Mode_3                                           'Hex decode for all 4 difits
        gosub Send_SPIData
    '    pauseus 2
        spiout.highbyte=Display_Test
        SPIout.lowbyte=display_test_mode_1                                     'Normal operation
        gosub Send_SPIData
    '    pauseus 2
    'Disply HELP as a signon.....
        spiout.highbyte=Digit_1
        SPIout.lowbyte=$0C                                                      'Disp 'H'
        gosub Send_SPIData
    '    pauseus 2
        spiout.highbyte=Digit_2
        SPIout.lowbyte=$0B                                                      'Disp 'E'
        gosub Send_SPIData
    '    pauseus 2
        spiout.highbyte=Digit_3
        SPIout.lowbyte=$0D                                                      'Disp 'L'
        gosub Send_SPIData
    '    pauseus 2
        spiout.highbyte=Digit_4
        SPIout.lowbyte=$0E                                                      'Disp 'P'
        gosub Send_SPIData
    '    pauseus 2
        
        stop                                                                    'See if it works......It's ALIVE!
    "If we knew what we were doing, it wouldn't be called research"
    - Albert Einstein

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