Hserin with Instant Interrupts.

[Demon]

Andy,

Do you have a particular need for USART? Or is this just to start getting familiar with DT Interrupts for whenever you may need them?

Have you been able to get something working?

Robert

[Demon]

Andy,

I've been pulling out my hair since last night trying to get a simple USART communication between 2 PICs (I needed to add it to my current project anyways).

Check this thread I found on Google and who started it:
http://www.picbasic.co.uk/forum/showthread.php?t=17282

I remember things forever, I just have problems recalling the information!

Robert

[Archangel]

Speaking from a position of ignorance, as I have NOT studied the above. This link to serial backpack uses DT_Ints & HSERIN together:
http://www.picbasic.co.uk/forum/cont...rial-backpacks

[Demon]

Andy,

Here's a little something to transmit. I left all the comments in it since I don't know your level of knowledge. I keep these in my programs since I often forget, or leave code on the shelf for year(s).

'--------------------------------------------------------------------'
' Author:  Demon                                                     '
' Date:    Dec 29th, 2014                                            '
' Project: RESIDENTIAL ALARM SYSTEM                                  '
' Circuit: Master                                                    '
'                                                                    '
' PIC:            18F44K22 @ 64MHz                                   '
' Language:       PIC Basic Pro v2.60c                               '
' Assembler:      MPASM v6.49                                        '
' IDE:            MicroCode Studio Plus from Mecanique v2.1.0.7      '
' Programmer:     MeLabs USB Programmer v4.32                        '
' LCD:            CASIL CCM-2040CSL v2.0 (HD44780 parallel interface)'
'                                                                    '
' All rights reserved.                                               '
'                                                                    '
' Use of parts of code is permitted as long as credit is given       '
' to the author.  Code may or may not work, use at your own risk     '
' including but not limitted to financial loss, heartbreak and       ' 
' loss of an eye.                                                    '
'--------------------------------------------------------------------'

'DEFINE  LOADER_USED 1
clear

' ---------------------------- Configuration Fuses -----------------------------
asm
 __CONFIG    _CONFIG1H, _FOSC_INTIO67_1H & _PLLCFG_ON_1H & _PRICLKEN_OFF_1H & _FCMEN_ON_1H & _IESO_OFF_1H
 __CONFIG    _CONFIG2L, _PWRTEN_ON_2L & _BOREN_SBORDIS_2L & _BORV_285_2L
 __CONFIG    _CONFIG2H, _WDTEN_OFF_2H
 __CONFIG    _CONFIG3H, _CCP2MX_PORTC1_3H & _PBADEN_OFF_3H & _CCP3MX_PORTE0_3H & _HFOFST_OFF_3H & _T3CMX_PORTB5_3H & _P2BMX_PORTC0_3H & _MCLRE_EXTMCLR_3H
 __CONFIG    _CONFIG4L, _STVREN_OFF_4L & _LVP_OFF_4L & _XINST_OFF_4L & _DEBUG_OFF_4L
endasm

' -------------------------------- Oscillator ----------------------------------
DEFINE OSC 64

' --------------------------------- Includes -----------------------------------
'INCLUDE "DT_INTS-18.bas"
'INCLUDE "ReEnterPBP-18.bas"
'INCLUDE "ReEnterPBP-18LP.bas"      ; PBP Re-entry for low priority external interrupt
'INCLUDE "Elapsed_INT-18_64MHz.bas"

' -------------------------------- Interrupts ----------------------------------

'xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
'                      RX must be done manually on Master                      x
'xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
;ASM
;----[High Priority Interrupts] ------------------------------------------------
;INT_LIST  macro    ; IntSource,        Label,           Type,   ResetFlag?
;        INT_Handler   TMR1_INT,   _ClockCount,   PBP,  yes
;    endm
;    INT_CREATE              ; Creates the High Priority interrupt processor

;----[Low Priority Interrupts] -------------------------------------------------
;INT_LIST_L  macro  ; IntSource,        Label,           Type,   ResetFlag?

;        INT_Handler   TMR3_INT,   _T3handler,   PBP,  yes
;    endm
;    INT_CREATE_L           ; Creates the Low Priority interrupt processor
;ENDASM

;DEFINE USE_LOWPRIORITY 1            ' Low priority interrupts

' ------------------------------------ USB -------------------------------------

' --------------------------------- Registers ----------------------------------
OSCCON  = %01110000                 ' OSCILLATOR CONTROL REGISTER
' bit 7 IDLEN: Idle Enable bit
'     R/W       1 = Device enters Idle mode on SLEEP instruction
'               0 = Device enters Sleep mode on SLEEP instruction
' bit 6-4 IRCF<2:0>: Internal RC Oscillator Frequency Select bits(2)
'     R/W       111 = HFINTOSC – (16 MHz)
'               110 = HFINTOSC/2 – (8 MHz)
'               101 = HFINTOSC/4 – (4 MHz)
'               100 = HFINTOSC/8 – (2 MHz)
'               011 = HFINTOSC/16 – (1 MHz)(3)
'           If INTSRC = 0 and MFIOSEL = 0:
'               010 = HFINTOSC/32 – (500 kHz)
'               001 = HFINTOSC/64 – (250 kHz)
'               000 = LFINTOSC – (31.25 kHz)
'           If INTSRC = 1 and MFIOSEL = 0:
'               010 = HFINTOSC/32 – (500 kHz)
'               001 = HFINTOSC/64 – (250 kHz)
'               000 = HFINTOSC/512 – (31.25 kHz)
'           If INTSRC = 0 and MFIOSEL = 1:
'               010 = MFINTOSC – (500 kHz)
'               001 = MFINTOSC/2 – (250 kHz)
'               000 = LFINTOSC – (31.25 kHz)
'           If INTSRC = 1 and MFIOSEL = 1:
'               010 = MFINTOSC – (500 kHz)
'               001 = MFINTOSC/2 – (250 kHz)
'               000 = MFINTOSC/16 – (31.25 kHz)
' bit 3 OSTS: Oscillator Start-up Time-out Status bit
'       R       1 = Device is running from the clock DEFINEd by FOSC<3:0> of the CONFIG1H register
'               0 = Device is running from the internal oscillator (HFINTOSC, MFINTOSC or LFINTOSC)
' bit 2 HFIOFS: HFINTOSC Frequency Stable bit
'       R       1 = HFINTOSC frequency is stable
'               0 = HFINTOSC frequency is not stable
' bit 1-0 SCS<1:0>: System Clock Select bit
'       R/W     1x = Internal oscillator block
'               01 = Secondary (SOSC) oscillator
'               00 = Primary clock (determined by FOSC<3:0> in CONFIG1H).

OSCCON2 = %00000100                 ' OSCILLATOR CONTROL REGISTER 2
' bit 7 PLLRDY: PLL Run Status bit
'     R         1 = System clock comes from 4xPLL
'               0 = System clock comes from an oscillator, other than 4xPLL
' bit 6 SOSCRUN: SOSC Run Status bit
'     R         1 = System clock comes from secondary SOSC
'               0 = System clock comes from an oscillator, other than SOSC
' bit 5 Unimplemented: Read as ‘0’.
' bit 4 MFIOSEL: MFINTOSC Select bit
'     R/W=0     1 = MFINTOSC is used in place of HFINTOSC frequencies of 500 kHz, 250 kHz and 31.25 kHz
'               0 = MFINTOSC is not used
' bit 3 SOSCGO(1): Secondary Oscillator Start Control bit
'     R/W=0     1 = Secondary oscillator is enabled.
'               0 = Secondary oscillator is shut off if no other sources are requesting it.
' bit 2 PRISD: Primary Oscillator Drive Circuit Shutdown bit
'     R/W=1     1 = Oscillator drive circuit on
'               0 = Oscillator drive circuit off (zero power)
' bit 1 MFIOFS: MFINTOSC Frequency Stable bit
'     R         1 = MFINTOSC is stable
'               0 = MFINTOSC is not stable
' bit 0 LFIOFS: LFINTOSC Frequency Stable bit
'     R         1 = LFINTOSC is stable
'               0 = LFINTOSC is not stable

OSCTUNE = %11000000                 ' OSCILLATOR TUNING REGISTER
' bit 7 INTSRC: Internal Oscillator Low-Frequency Source Select bit
'     R/W       1 = 31.25 kHz device clock derived from the MFINTOSC or HFINTOSC source
'               0 = 31.25 kHz device clock derived directly from LFINTOSC internal oscillator
' bit 6 PLLEN: Frequency Multiplier 4xPLL for HFINTOSC Enable bit(1)
'     R/W       1 = PLL enabled
'               0 = PLL disabled
' bit 5-0 TUN<5:0>: Frequency Tuning bits – use to adjust MFINTOSC and HFINTOSC frequencies
'     R/W       011111 = Maximum frequency
'               011110 =
'               • • •
'               000001 =
'               000000 = Oscillator module (HFINTOSC and MFINTOSC) are running at the factory calibrated frequency.
'               111111 =
'               • • •
'               100000 = Minimum frequency

PMD0 = %10111111                    ' PERIPHERAL MODULE DISABLE REGISTER 0
' bit 7 UART2MD: UART2 Peripheral Module Disable Control bit
'               1 = Module is disabled, Clock Source is disconnected, module does not draw digital power
'               0 = Module is enabled, Clock Source is connected, module draws digital power
' bit 6 UART1MD: UART1 Peripheral Module Disable Control bit
'               1 = Module is disabled, Clock Source is disconnected, module does not draw digital power
'               0 = Module is enabled, Clock Source is connected, module draws digital power
' bit 5 TMR6MD: Timer6 Peripheral Module Disable Control bit
'               1 = Module is disabled, Clock Source is disconnected, module does not draw digital power
'               0 = Module is enabled, Clock Source is connected, module draws digital power
' bit 4 TMR5MD: Timer5 Peripheral Module Disable Control bit
'               1 = Module is disabled, Clock Source is disconnected, module does not draw digital power
'               0 = Module is enabled, Clock Source is connected, module draws digital power
' bit 3 TMR4MD: Timer4 Peripheral Module Disable Control bit
'               1 = Module is disabled, Clock Source is disconnected, module does not draw digital power
'               0 = Module is enabled, Clock Source is connected, module draws digital power
' bit 2 TMR3MD: Timer3 Peripheral Module Disable Control bit
'               1 = Module is disabled, Clock Source is disconnected, module does not draw digital power
'               0 = Module is enabled, Clock Source is connected, module draws digital power
' bit 1 TMR2MD: Timer2 Peripheral Module Disable Control bit
'               1 = Module is disabled, Clock Source is disconnected, module does not draw digital power
'               0 = Module is enabled, Clock Source is connected, module draws digital power
' bit 0 TMR1MD: Timer1 Peripheral Module Disable Control bit
'               1 = Module is disabled, Clock Source is disconnected, module does not draw digital power
'               0 = Module is enabled, Clock Source is connected, module draws digital power

PMD1 = %11011111                    ' PERIPHERAL MODULE DISABLE REGISTER 1
' bit 7 MSSP2MD: MSSP2 Peripheral Module Disable Control bit
'               1 = Module is disabled, Clock Source is disconnected, module does not draw digital power
'               0 = Module is enabled, Clock Source is connected, module draws digital power
' bit 6 MSSP1MD: MSSP1 Peripheral Module Disable Control bit
'               1 = Module is disabled, Clock Source is disconnected, module does not draw digital power
'               0 = Module is enabled, Clock Source is connected, module draws digital power
' bit 5 Unimplemented: Read as ‘0’
' bit 4 CCP5MD: CCP5 Peripheral Module Disable Control bit
'               1 = Module is disabled, Clock Source is disconnected, module does not draw digital power
'               0 = Module is enabled, Clock Source is connected, module draws digital power
' bit 3 CCP4MD: CCP4 Peripheral Module Disable Control bit
'               1 = Module is disabled, Clock Source is disconnected, module does not draw digital power
'               0 = Module is enabled, Clock Source is connected, module draws digital power
' bit 2 CCP3MD: CCP3 Peripheral Module Disable Control bit
'               1 = Module is disabled, Clock Source is disconnected, module does not draw digital power
'               0 = Module is enabled, Clock Source is connected, module draws digital power
' bit 1 CCP2MD: CCP2 Peripheral Module Disable Control bit
'               1 = Module is disabled, Clock Source is disconnected, module does not draw digital power
'               0 = Module is enabled, Clock Source is connected, module draws digital power
' bit 0 CCP1MD: CCP1 Peripheral Module Disable Control bit
'               1 = Module is disabled, Clock Source is disconnected, module does not draw digital power
'               0 = Module is enabled, Clock Source is connected, module draws digital power

PMD2 = %00001111                    ' PERIPHERAL MODULE DISABLE REGISTER 2
' bit 7-4 Unimplemented: Read as ‘0’
' bit 3 CTMUMD: CTMU Peripheral Module Disable Control bit
'               1 = Module is disabled, Clock Source is disconnected, module does not draw digital power
'               0 = Module is enabled, Clock Source is connected, module draws digital power
' bit 2 CMP2MD: Comparator C2 Peripheral Module Disable Control bit
'               1 = Module is disabled, Clock Source is disconnected, module does not draw digital power
'               0 = Module is enabled, Clock Source is connected, module draws digital power
' bit 1 CMP1MD: Comparator C1 Peripheral Module Disable Control bit
'               1 = Module is disabled, Clock Source is disconnected, module does not draw digital power
'               0 = Module is enabled, Clock Source is connected, module draws digital power
' bit 0 ADCMD: ADC Peripheral Module Disable Control bit
'               1 = Module is disabled, Clock Source is disconnected, module does not draw digital power
'               0 = Module is enabled, Clock Source is connected, module draws digital power

ANSELA = %00000000                  ' Set ports to digital
ANSELB = %00000000
ANSELC = %00000000
ANSELD = %00000000
ANSELE = %00000000

ADCON0 = %00000000                  ' Disable ADC

' ---------------------------------- EUSART ------------------------------------
'xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
'                             For MULTIPLE Slaves                              x
'                                                                              x
'                 Do not use USART TX pin for HSEROUT on Slave                 x
'                   Use SEROUT at 115200 baud open collector                   x
'                                                                              x
'                                   - or -                                     x
'                                                                              x
'                   Enable USART TX pin for HSEROUT on Slave                   x
'                              Transmit to Master                              x
'                                Disable TX pin                                x
'                            (my preferred method)                             x
'xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx

'DEFINE CHAR_PACING 1000 
DEFINE HSER_RCSTA 90h               ' Enable serial port & continuous receive
DEFINE HSER_TXSTA 24h               ' Enable transmit, BRGH = 1
DEFINE HSER_CLROERR 1               ' Clear overflow automatically
DEFINE HSER_SPBRG 138               ' 115200 Baud @ 64MHz, -0,08%

RCSTA = $90                         ' Enable serial port & continuous receive
TXSTA = $24                         ' Enable transmit, BRGH = 1
SPBRG = 138                         ' 115200 Baud @ 64MHz, -0.08%
SPBRGH = 0                          ' Baud Rate Generator high byte
BAUDCON.3 = 1                       ' Enable 16 bit Baud Rate Generator

'                                       Override switches
'RCSTA1.4 = 0                        ' Disable USART RX1 function
'RCSTA2.4 = 0                        ' Disable USART RX2 function
'TXSTA1.5 = 0                        ' Disable USART TX1 function
'TXSTA2.5 = 0                        ' Disable USART TX2 function

' ------------------------------------ LCD -------------------------------------
DEFINE  LCD_DREG        PORTA
DEFINE  LCD_DBIT        0
DEFINE  LCD_RSREG       PORTE   ' Register Select
DEFINE  LCD_RSBIT       0
DEFINE  LCD_EREG        PORTE   ' Enable
DEFINE  LCD_EBIT        1
DEFINE  LCD_BITS        4
DEFINE  LCD_LINES       4
'DEFINE  LCD_COMMANDUS 1500          ' Set command delay time in microseconds
'DEFINE  LCD_DATAUS    50            ' Set data delay time in microseconds

' ------------------------------ Port directions -------------------------------
'xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
'             - From Microchip PIC datasheet in EUSART section -               x
' For all modes of EUSART operation, the TRIS control bits corresponding to    x
' the RXx/DTx and TXx/CKx pins should be set to ‘1’. The EUSART control will   x
' automatically reconfigure the pin from input to output, as needed.           x
'xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
TRISA = %00000000                   ' 0 = output 
TRISB = %00000000                   ' 1 = input
TRISC = %11000000
TRISD = %00000000
TRISE = %00000000

' ----------------------------------- Ports ------------------------------------
PORTA = %00000000                   ' 0 = low  (GND)
PORTB = %00000000                   ' 1 = high (5V)
PORTC = %00000000
PORTD = %00000000
PORTE = %00000000

' --------------------------------- Constants ----------------------------------
conSlave1   CON 1                   ' Slave address
conSlave2   CON 2
conEcho     con 69                  ' Slave Echo command (Dec 69 = ASCII "E")

' --------------------------------- Variables ----------------------------------
pinTX       var PortC.4             ' This pin is used for debugging only

bytLoop     var byte                ' Loop control
bytAddress  var byte                ' Slave address
bytCommand  var byte                ' Slave command

wrdCS       var word                ' CheckSum

bytBuffer1  var byte[8]             ' Data buffers sent to Slave
bytBuffer2  var byte[8]

' ------------------------------- Program start --------------------------------
    for bytLoop = 0 to 7            ' Initialize arrays with "fake data"
      bytBuffer1[bytLoop] = bytLoop
      bytBuffer2[bytLoop] = bytLoop
    next bytLoop

    pause 500

'@ INT_ENABLE  TMR1_INT 

    goto MainProgram

' -------------------------------- Subroutines ---------------------------------
'T1handler:
'    T1CON.0 = 0                     ' Stop timer
'@ INT_RETURN

' -------------------------------- Main Program --------------------------------
MainProgram:
    
    Lcdout $fe, 1, "USART sample program"

    bytAddress  = conSlave1         ' Slave system address
    bytCommand  = conEcho           ' Slave echo command
    wrdCS = bytAddress + bytCommand ' Checksum = Address + Command
    for bytLoop = 0 to 7            ' Checksum = Checksum + Buffer1 + Buffer2
      wrdCS = wrdCS + bytBuffer1[bytLoop]
      wrdCS = wrdCS + bytBuffer2[bytLoop]
    next bytLoop

    pinTX = 1                       ' Signal the start of Transmit to Slave PIC
    hserout [dec3 bytAddress, dec2 bytCommand,   _
             str bytBuffer1\8, str bytBuffer2\8, _
             dec5 wrdCS.byte1, dec5 wrdCS.byte0]
    pinTX = 0                       ' Signal the end
    
    Lcdout $fe, $c0, "Addr:", dec3 bytAddress, "  Cmd:", dec2 bytCommand
    Lcdout $fe, $94, "Buf:", dec1 bytBuffer1[0], dec1 bytBuffer1[1], dec1 bytBuffer1[2], _
                             dec1 bytBuffer1[3], dec1 bytBuffer1[4], dec1 bytBuffer1[5], _
                             dec1 bytBuffer1[6], dec1 bytBuffer1[7],                     _
                             dec1 bytBuffer2[0], dec1 bytBuffer2[1], dec1 bytBuffer2[2], _
                             dec1 bytBuffer2[3], dec1 bytBuffer2[4], dec1 bytBuffer2[5], _
                             dec1 bytBuffer2[6], dec1 bytBuffer2[7]
    Lcdout $fe, $D4, "Checksum:", dec5 wrdCS.byte1, dec5 wrdCS.byte0

'    goto MainProgram
end

You can comment out the LCD stuff if you don't need it. I use a Saleae probe to see the data on the TX pin. The normal method is to connect to a PC using MAX232 chip (search forum for circuit).

The interrupt is commented out because it is just a placeholder. It is not in working order, it's just there so I remember where I put stuff in my program. I adjust it to my needs when I need it. In this case, we don't need one in the Master.

This shows how the data is sent across the TX line (display is too narrow on laptop).



Robert

[Demon]

The checksum method above is just a basic one, there are many formulas, this was good enough for me.

The code above is a basic structured approach. I try to keep all my "stuff" in the same order, makes it easier for me to find stuff (to copy&paste into new programs). Nothing is forcing you to organize your code, but there are some exceptions (DT_INT must be the first of DT includes). There is also paging issues, but that's advanced stuff. Generally; config fuses at top, then defines, registers, ports, variables, code and then data (it can be anywhere, it's just easier when it's at the bottom of the scroll range - especially when you have LOTS of data statements).

Comments are your friend and take no space.

I don't know how complex your PIC network will be, but the code above gives you a basic design. The Address can be for a single PIC, or a Call-All-PICs address (999 or whatever you want). The Command gives you flexibility in telling the slave what code to execute. The Buffers can be whatever you want (within PBP/PIC limits), mine will be at least 55 bytes. Same with the address and command; they can be whatever format you want.

There are many ways to handle the actual message size. Some send one byte at a time, some send the longest record and let the slave figure out what it needs. Another way is to send a command first, the slave determines which size wil be sent, signals the master to send the data and then waits for it. You transfer less bytes but you do more data transfers; if my buffer lengths vary little, I send it all, if there's a HUGE difference in size, it's worth telling the slave what to wait for.

There's no limit to how complex you can handle communications. I suggest you stick with whatever makes you happy.

(have to get back to my PC, wife doesn't like having parts in the kitchen)

Robert