PBP code to read R/C signal from receiver

[malc-c]

Guys,

Have tried searching the net and this forum, but nothing comes up, and as I'm a bit rusty on PBP, I'm after some pointers as to how to read the PPM signal from a normal RC receiver (1 -2ms repeated every 20ms).

I've got some ASM code that already does this, but really want to learn and develope PBP a little more. One search did turn up something on RC groups, but Alain has removed the source code

[Acetronics2]

Hi, Malc

What are you looking for exactly ???

The basic reading is simply achieved only with a PULSIN Command ....

Alain

[DanPBP]

Short example:

'-------------------------------------------------------------------------------
'-------------------------------------------------------------------------------

@ DEVICE PIC12F683, MCLR_OFF
@ DEVICE PIC12F683, INTRC_OSC_NOCLKOUT
@ DEVICE PIC12F683, WDT_OFF
@ DEVICE PIC12F683, BOD_ON
@ DEVICE PIC12F683, PWRT_ON

'-------------------------------------------------------------------------------

OSCCON  = %01110000    ' Internal 4MHz osc
ADCON0 = 0             ' A/D off
CMCON0 = 7             ' Comparators off
ANSEL = 0	           ' Set all digital
WPU = 0                ' Internal pull-ups = off
OPTION_REG = %10000000 ' Pull-ups = off, GPIO.2 = I/O, prescaler to Timer1
GPIO = %00000000       ' All outputs = 0 on boot
TRISIO = %00001000     ' GPIO.3 input, GPIO.0,2,3,4,5 output

'-------------------------------------------------------------------------------

signal VAR GPIO.3
pulse  VAR BYTE

'-------------------------------------------------------------------------------

main:
       PulsIn signal, 1, pulse ' reads signal from receiver

       IF (pulse >= 148) AND (pulse <= 152) Then
          Low GPIO.0 ' turns LED off
       Else
            High GPIO.0 ' turns LED on
       EndIF

       GoTo main

'-------------------------------------------------------------------------------

End

'-------------------------------------------------------------------------------
'-------------------------------------------------------------------------------

[malc-c]

Thanks for the code example. I'll hook up a receiver to my Easypic5 board and have a play... I'll also have a read of the online manual

[malc-c]

Dan,

I've tried the following with a 12F675 and whilst it compiles and loads OK it doesn't do anything

 @ __CONFIG _INTRC_OSC_NOCLKOUT & _WDT_ON & _PWRTE_ON & _MCLRE_OFF & _BODEN_ON

 __CONFIG
 _INTRC_OSC_NOCLKOUT
 _WDT_ON
 _PWRTE_ON
 _MCLRE_OFF
 _BODEN_ON

OPTION_REG = %10000000 ' Pull-ups = off, GPIO.2 = I/O, prescaler to Timer1
GPIO = %00000000       ' All outputs = 0 on boot
TRISIO = %00001000     ' GPIO.3 input, GPIO.0,2,3,4,5 output
ANSEL = 0	           ' Set all digital
WPU = 0                ' Internal pull-ups = off
'-------------------------------------------------------------------------------

signal VAR GPIO.3
pulse  VAR BYTE

'-------------------------------------------------------------------------------

main:
       PulsIn signal, 1, pulse ' reads signal from receiver

       IF (pulse >= 148) AND (pulse <= 152) Then
          Low GPIO.0 ' turns LED off
       Else
            High GPIO.0 ' turns LED on
       EndIF

       GoTo main

'-------------------------------------------------------------------------------

End

GPIO.0 is high all the time. GPIO.3 glows faint on the Easypic and brightens when the switch on the TX is activated indicating the PPM signals are being received on GPIO.3

I've also loaded some hex generated from assembly that works so the connections are sound. Any ideas ???

[malc-c]

Edit:

This seems to work

main:
       PulsIn signal, 1, pulse ' reads signal from receiver

       IF (pulse >= 100) AND (pulse <= 160) Then
          Low GPIO.0 ' turns LED off
       Else
            High GPIO.0 ' turns LED on
       EndIF

       GoTo main

seems the range between >= and <= was the issue

[Acetronics2]

There was no issue, Malc

Led OFF for Neutral , ON for everything else.

a bit surprising, but ... it is !

Alain

[malc-c]

No issue, just the the original range didn't work. Once I changed the values between the <= and >= then it worked !

[DanPBP]

I'm glad the code worked for you... Wish there were more threads about R/Cs electronics... I own 25 R/C trucks from Traxxas and now a heli clone of the Trex500 and many of them have PICs turning on/off lights, flashers, blilnkers, neons, sirens, and a few more things... PICs are great for R/C projects!!!

[malc-c]

Dan, have to agree with you. It would be nice to see some more RC related PIC / PBP stuff.

Maybe we could start a thread and request the mods to sticky it in the code examples section ????