Rc signal help

[HenrikOlsson]

Hi,
The 'F675 has one comparator AND an A/D converter.
The comparator is turned off with CMCON=7 and the the pins for the A/D is set to digital only with ANSEL=0.

However....

You're using GP3 for your input and that pin is not connected to either the comparator or the A/D so none of the above should really matter but I'm not sure. GP3 is however the MCLR pin and it seems you have a typo in your config setting. I THINK it should be MCLR_OFF and not MCLRE_OFF. - try it.

Also, you're using a byte-size variable to store the pulsewidth, try switching that to a Word instead.

/Henrik Olsson.

[geckogrotto]

Hi,
The 'F675 has one comparator AND an A/D converter.
The comparator is turned off with CMCON=7 and the the pins for the A/D is set to digital only with ANSEL=0.

However....

You're using GP3 for your input and that pin is not connected to either the comparator or the A/D so none of the above should really matter but I'm not sure. GP3 is however the MCLR pin and it seems you have a typo in your config setting. I THINK it should be MCLR_OFF and not MCLRE_OFF. - try it.

Also, you're using a byte-size variable to store the pulsewidth, try switching that to a Word instead.

/Henrik Olsson.

I tried swapping back and forth on ANSEL and CMCON neither seem to make a difference. Also when I change to MCLR_OFF it errors and will not even compile.

I tried using word as well no luck.

[Acetronics2]

Hi, gecko

No problem compiling with MPASM 7.41 and PbP 2.46a ...

Error [ 118 ] is to forget when using @ __config

May be add END ... at the end !!!, but that's not compulsory ( good habit then ... )

Alain

[geckogrotto]

Hi, gecko

No problem compiling with MPASM 7.41 and PbP 2.46a ...

Error [ 118 ] is to forget when using @ __config

May be add END ... at the end !!!, but that's not compulsory ( good habit then ... )

Alain

I'm not sure I understand what your saying exactly but.

'12F675
@ __CONFIG _INTRC_OSC_CLKOUT & _WDT_OFF & _MCLR_OFF & _CP_OFF
DEFINE OSC 4 
OPTION_REG.5 = 0                                                       ' clock source internal
CMCON = 7 
ANSEL=0

Pulselen   var word                                                 ' Pulselen can be 0 - 255, 100 = 1 ms, 200 = 2 ms
Init       var word                                                 ' Init used to flash LED
Clear                                                                  ' set all variables = 0

Input GPIO.3                                                           ' set pin 5 to RX signal

ReadPWM:
   PulsIn GPIO.3, 1,Pulselen                 ' pin 4 - read high pulse length, times out after .65535 seconds 
   pause 15                   
   If Pulselen < 50 Then GoTo Blink           ' no signal  -> blink led
   If Pulselen > 75 Then GoTo solid           ' signal  -> Solid led
   GoTo ReadPWM               
        
Blink: 
   For Init = 1 To 3                                                   ' blink led 3 times
      High GPIO.1                                                      
      pause 200                                                      
      Low GPIO.1                                                     
      pause 200                                                      
   Next
pause 1000		    
 GoTo ReadPWM 
 
Solid: 
      High GPIO.1                                                      
      pause 3000                                                      
      Low GPIO.1
      pause 200
 GoTo ReadPWM 
 END

fails compile saying

error 113 Symbol not previously defined (MLCR_OFF)

When I use _MCLRE_OFF instead it compiles with no error.

[malc-c]

Just a few comments from my basic understanding of RC

Pulselen   var word        ' Pulselen can be 0 - 255, 100 = 1 ms, 200 = 2 ms
Init       var word          ' Init used to flash LED
Clear                           ' set all variables = 0

Input GPIO.4                ' set pin 3 to RX signal - changed as GPIO3 is not ideal

ReadPWM:
   PulsIn GPIO.4, 1,Pulselen    ' pin 3 - read high pulse length, times out after .65535 seconds 
   pause 15                   
   If Pulselen < 50 Then GoTo Blink     ' no signal  -> blink led
   If Pulselen > 75 Then GoTo solid     ' signal  -> Solid led
   GoTo ReadPWM

If you read the comments for pulselen it states that 100 = 1ms and 200 = 2ms, but your if / then statement states that if its less than 50 go blink. If you are monitoring a "normal" PPM signal from a receiver, the pulse length will be around 1ms for low stick and 2ms for full stick, with 1.5ms at centre. So even at low stick the signal will be 1ms or a pulse length of 100, it will never be lower than 50, and this the code will never jump to flash.

I too had to change the config line to MCLRE_OFF for it to program without error

EDIT:
Oh and one other thing that may be causing the problem is that the RX will be sending the PPM pulse every 20ms, so you will need to get the timing right so that the pin is checked for a pulse at the right time. According to code it times out after .65535 seconds, maybe you need to make this time out after 20ms so it loops back round. Most of my experiments with other languages used the pre-scaler to get the timer to roll over at the desired timing if a pulse wasn't present. Maybe some of the more experienced guys can jump in here as I don't know if PBP features this option ?

[Archangel]

'12F675
@ DEVICE pic12F675, INTRC_OSC_NOCLKOUT
' System Clock Options
@ DEVICE pic12F675, MCLR_OFF
' Master Clear Options (Internal)
@ DEVICE pic12F675, WDT_OFF
' Watchdog Timer
@ DEVICE pic12F675, CPD_OFF


DEFINE OSC 4
OPTION_REG.5 = 0 ' clock source internal
CMCON = 7
ANSEL=0

Pulselen var word ' Pulselen can be 0 - 255, 100 = 1 ms, 200 = 2 ms
Init var word ' Init used to flash LED
Clear ' set all variables = 0

Input GPIO.3 ' set pin 5 to RX signal

ReadPWM:
PulsIn GPIO.3, 1,Pulselen ' pin 4 - read high pulse length, times out after .65535 seconds
pause 15
If Pulselen < 50 Then GoTo Blink ' no signal -> blink led
If Pulselen > 75 Then GoTo solid ' signal -> Solid led
GoTo ReadPWM

Blink:
For Init = 1 To 3 ' blink led 3 times
High GPIO.1
pause 200
Low GPIO.1
pause 200
Next
pause 1000
GoTo ReadPWM

Solid:
High GPIO.1
pause 3000
Low GPIO.1
pause 200
GoTo ReadPWM
END

[geckogrotto]

ugg that doesn't compile either
A bunch of illegal opcode warnings and errors
207 and 122.