rfPIC Serin problem

[gavo]

Hi Bruce,

Many thanks, i will try that ;-)

Regards,

Gavin

[gavo]

Hi Bruce,

I have used the ANSEL = 0 and the device works until I plug the receiver board in, when I plug the receiver board in the device "seems"to hang, I then put a scope on RC1 and noticed quite a crazy waveform, I then pressed the button on the transmitter and it took around +- 20 sec's before the receiver recognised the transmitter's data and then the device functioned correctly. I am assuming I have something wrong with my transmitter serout routine as I am not sure why it take so long for the receiver to recognise the transmitter, have you some ideas?

Many Thanks,

Regards,

Gavin

[Bruce]

Hi Gavin,

I'm just guessing, but are you using a Microchip rfPIC dev kit?

[Bruce]

I'm assuming this is the hardware you have, so I broke out my rfPIC eval kit, and played
a bit. Give these a try.

Receiver example;

'****************************************************************
'*  Name    : rfPIC_RX.BAS                                      *
'*  Author  : B. Reynolds                                       *
'*  Notice  : Copyright (c) 2007 Reynolds Electronics           *
'*          : All Rights Reserved                               *
'*  Date    : 10/09/2007                                        *
'*  Version : 1.0 (Momentary decoder version)                   *
'*  Notes   : 2-Bit decoder for Microchip RF dev system         *
'*          : with rfRXD0420 module installed in PICkit 1 board *
'****************************************************************
@ DEVICE PIC16F676,MCLR_OFF,INTRC_OSC_NOCLKOUT,WDT_OFF,BOD_OFF
@ DEVICE PWRT_ON,PROTECT_OFF
    
    DEFINE OSC 4
    DEFINE NO_CLRWDT 1      ' Watchdog timer is disabled, so we don't need to reset it
    DEFINE OSCCAL_1K 1      ' load factory calibration value
    DEFINE INTHAND RESET_VT ' Interrupt on Timer1 overflow to reset outputs in 65.5mS
                            ' if no serial data received in this time period
    SYMBOL  D_IN = PORTC.1  ' data input pin
    SYMBOL  TMR1IF = PIR1.0 ' Timer1 overflow interrupt flag (reset in int handler)
    SYMBOL  TMR1IE = PIE1.0 ' Timer1 interrupt enable bit
    
    'Variables for saving state in interrupt handler
    wsave   VAR	BYTE $5F system	   ' Saves W
    ssave   VAR	BYTE bank0 system  ' Saves STATUS
    psave   VAR	BYTE bank0 system  ' Saves PCLATH
    fsave   VAR	BYTE bank0 system  ' Saves FSR
    
    ' Working variables
    MATCH     VAR BYTE bank0 system ' Match variable
    DAT_OUTB  VAR BYTE  ' Holds decoded data for output
    DAT_IN1   VAR BYTE  ' 1st Data byte
    DAT_IN2   VAR BYTE  ' 2nd Data byte for verify
    CHK_SUM   VAR BYTE  ' Holds checksum received
    CheckSum  VAR BYTE  ' Computed checksum of all bytes received
    LOOPS     VAR BYTE  ' Loop var
    
    ' Constants
    Synch    CON "~"    ' 01111110 synch byte
    N2400    CON 16780  ' 2400 bps inverted
    N4800    CON 188    ' 4800 bps inverted
    
     ' hardware init
    PORTA = 0
    TRISA = %00111001   ' RA1 and RA2 are LED outputs
    PORTC = 0           ' Clear outputs on power-up
    TRISC = %00111110   ' RC1 = RF input
    IOC = 0             ' Interrupt on change disabled
    VRCON = 0           ' Comparator Vref disabled
    CMCON = 7           ' Disable comparators
    ANSEL = 0           ' disable A/D
    OPTION_REG = 128    ' Pull-ups off
    
    ' Setup Timer1 for resets after ~65.5mS
    T1CON = %00000000   ' Internal clock, 1:1 prescale, Timer1 off for now
    TMR1L = 0 
    TMR1H = 0           ' Timer1 low & high bytes cleared
    TMR1IF = 0          ' Clear Timer1 overflow flag before enabling interrupt
    TMR1IE = 1          ' Enable Timer1 overflow interrupt
    INTCON = %11000000  ' Global & peripheral ints enabled
    MATCH = 0           ' Clear match count
    GOTO    MAIN        ' Jump over int handler
    
ASM  ; Timer1 overflow interrupt resets outputs when no valid key press
     ; is detected within ~65mS
RESET_VT
    movwf  wsave	 ; Save W
    swapf  STATUS, W     ; Swap STATUS to W (swap avoids changing STATUS)
    clrf   STATUS	 ; Clear STATUS
    movwf  ssave	 ; Save swapped STATUS
    movf   PCLATH, W     ; Move PCLATH to W
    movwf  psave	 ; Save PCLATH
    movf   FSR, W	 ; Move FSR to W
    movwf  fsave         ; Save FSR
    
    ; Do interrupt stuff here
    bcf    T1CON,TMR1ON  ; Stop Timer1
    clrf   TMR1L         ; Clear low byte
    clrf   TMR1H         ; Clear high byte
    bcf    PIR1,TMR1IF   ; Clear Timer1 interrupt flag bit
    clrf   PORTA         ; Clear outputs on button release
    clrf   MATCH         ; Clear match variable
    
    ; Restore FSR, PCLATH, STATUS and W registers
    movf    fsave, W	 ; retrieve FSR value
    movwf   FSR		 ; Restore it to FSR
    movf    psave, W	 ; Retrieve PCLATH value
    movwf   PCLATH	 ; Restore it to PCLATH
    swapf   ssave, W     ; Get swapped STATUS value (swap to avoid changing STATUS)
    movwf   STATUS	 ; Restore it to STATUS
    swapf   wsave, F	 ; Swap the stored W value
    swapf   wsave, W	 ; Restore it to W (swap to avoid changing STATUS)
    bsf     T1CON,TMR1ON ; Re-enable Timer1 before exiting interrupt handler
    retfie		 ; Return from the interrupt
ENDASM
 
MAIN:          
    ' Fire up Timer1 before entry to serial input routine
    T1CON.0 = 1
    
    ' at 4MHz Timer1 overflows in 65536 * 1uS (~65.5mS) if no Synch byte
    ' and serial data arrive on time. SERIN2 timeout & label options
    ' are useless with a noisy RF receiver output - as noise continually
    ' resets the timeout period causing it to hang forever.
    
    ' Wait for Synch byte, then get new inbound data & checksum
    SERIN2 D_IN,N2400,[WAIT(Synch),DAT_IN1,DAT_IN2,CHK_SUM]
    
    T1CON.0 = 0    ' Stop Timer1 once we've received data
    TMR1L = 0      ' Clear low byte
    TMR1H = 0      ' Clear high byte
    
    ' / **** Begin data validation **** /
    
    ' Calculate checksum by adding 2 data bytes together
    CheckSum = DAT_IN1 + DAT_IN2
    
    ' Test new checksum against one received in CHK_SUM
    IF CheckSum != CHK_SUM THEN MAIN ' Failed checksum, return
    
    ' Test data bytes for match
    IF (DAT_IN1) != (DAT_IN2) THEN MAIN ' Failed data comparison, return
    
    MATCH = MATCH + 1        ' We have a match so increment match count
    IF MATCH = 2 THEN DECODE ' Everything matched twice, we're good
    GOTO Main                ' Else do it all over
    
    ' Everything looking good - so place new data on outputs
DECODE:
    ' Place decoded values on port pins..
    PORTA = DAT_IN1 & %00000110
    DAT_IN1 = !DAT_IN2  ' Destroy the match
    MATCH = 0 
    GOTO MAIN
        
    END

Transmitter example;

'****************************************************************
'*  Name    : rfPIC_TX.BAS                                      *
'*  Author  : B. Reynolds                                       *
'*  Notice  : Copyright (c) 2007 Reynolds Electronics           *
'*          : All Rights Reserved                               *
'*  Date    : 10/09/2007                                        *
'*  Version : 1.0                                               *
'*  Notes   : 2-BIT Encoder for remote control with the         *
'*          : rfPIC12F675 on Microchip rfPIC demo board         *
'****************************************************************
@ DEVICE PIC12F675,MCLR_OFF,INTRC_OSC_NOCLKOUT,WDT_OFF,BOD_OFF
@ DEVICE PWRT_ON,PROTECT_OFF
    
    ' With rfRXD0420 module installed in PICkit 1 board;
    ' SW1 toggles LED D6 on PICkit 1 board
    ' SW2 toggles LED D7 on PICkit 1 board
    DEFINE OSC 4
    DEFINE NO_CLRWDT 1
    DEFINE OSCCAL_1K 1
    
    SYMBOL D_OUT = GPIO.2 ' RF serial data output
    SYMBOL E_OUT = GPIO.5 ' RF transmitter enable output
    
    DAT_OUT VAR BYTE    ' Holds 8-bit data byte
    LOOPS   VAR BYTE    ' Loop var
    CHK_SUM VAR BYTE    ' Holds calculated checksum of outbound data
    BAUD    VAR WORD    ' Holds baud rate
    
    ' Constants
    PreAmble CON $A5    ' 10100101 preamble
    Synch    CON "~"    ' 01111110 synch byte
    N4800    CON 188    ' 4800 bps 
    N2400    CON 16780  ' 2400 bps
    GUARD    CON 5      ' 5mS guard time pause
    
    ' hardware init 
    GPIO = 0            ' Everything off on boot
    ' GPIO.2=data out, GPIO.5=RF enable, GPIO.3,4=SW1/SW2 switch inputs (rfPIC board)
    TRISIO = %00011011  '
    ANSEL = 0           ' Disable A/D
    INTCON = %00001000  ' Enable port change wakeup from sleep
    WPU = %00010000     ' pull-up on for GPIO.4 (external pull-up already on GPIO.3)
    IOC = %00011000     ' Wakeup on change enabled for GPIO.3,4
    VRCON = 0           ' Disable internal Vref
    CMCON = 7           ' Disable comparators
    OPTION_REG = 0      ' Pull-ups on
    
    D_OUT = 0           ' Idles low for inverted serial output
    E_OUT = 0           ' Enable for RF transmitter=0 (transmiter off)
    BAUD = N2400        ' Set baud rate here
    
Main:    
    ' Read port to clear missmatch, if with no buttons pressed, then
    ' clear int-on-change flag & snooze until wake up on change. This
    ' conserves battery power on the demo board with 3V coin cell.
    IF (GPIO.3=1) AND (GPIO.4=1) THEN ' pins will be 0 only when buttons are pressed
     E_OUT=0         ' Disable transmitter
     INTCON.0 = 0    ' No buttons down, so clear int on change flag
     @ SLEEP         ' and start snoozin..zzzzzzzzzzz
     @ NOP           ' Do nothing for 1st instruction on wake-up
    ENDIF
    E_OUT=1          ' Enable transmitter (+ lights RFEN LED on demo board)
    PAUSEUS 25       ' Allow RF stage to stabilize
    
    ' Button pressed (or being held down), so keep going   
Encode:  
    ' Only DAT_OUT bits 1 and 2 are used. We add a few 1's in bit
    ' positions 0,3,5,7 to balance out the data packet being sent.
    DAT_OUT = %10101001
    ' Get data on button inputs & invert 0's to 1's
    DAT_OUT.0[1]=~GPIO.3
    DAT_OUT.0[2]=~GPIO.4
    INTCON.0 = 0  ' Clear int on change flag
      
    ' Build checksum of 2 data bytes
    CHK_SUM = (DAT_OUT * 2)
    
Transmit:
    SEROUT2 D_OUT,BAUD,[PreAmble,Synch,DAT_OUT,DAT_OUT,CHK_SUM]
    PAUSE GUARD ' 5mS guard time gives decoder time to respond,calculate,change,etc.
    
    GOTO Main
        
    END

You should be able to modify these pretty easily for your own application.

[gavo]

Hi Bruce,

Many thanks I will give it a bash ;-), regards, Gavin

[onepiece]

Hi,

I'm a beginner in PIC programming and now struggling to program rfPIC12F675. I'm confused on how TRISIO assign input and output.

movlw b'00010000' ; set GP<4> as digital inputs and other bits as output
movwf trisio ; and set others as outputs/mclr/clkout/osc

However, when I try to simulate it, and try to observe the output (we fire the GP4 as high),
it seems that the output is 0 all the time.

Other than setting the trisio, do I need to call any other instructions to make sure the data is being read in - send to modulation - and then output accordingly.

I'm a bit lost now. Hope that you can help

[Bruce]

The data sheet has everything you're looking for.

And if you're looking for examples in Microchip assembler, then check the Microchip website for rfPIC examples. Here's a direct link to rfPIC examples; http://www.microchip.com/stellent/id...cName=en010060