PBP projects for R/C models

[malc-c]

Hi,

Following on from a suggestion on the main PBP forum, it is hoped to get people to post up code snippets for anything RC model related. I'll start the ball rolling by posting code that makes an LED pulse like a beacon and is controllable from a transmitter. - This was a result of my own bit of code and suggestions from guys on this forum on how to use pulsein command to detect the signal from the receiver.

'****************************************************************
'*  Name    : RC Input - 12F675                                 *
'*  Author  :                                                   *
'*  Notice  : Copyright (c) 2009                                *
'*          : All Rights Reserved                               *
'*  Date    : 27/10/2009                                        *
'*  Version : 1.0                                               *
'*  Notes   :                                                   *
'*          :                                                   *
'****************************************************************

' set up PIC config

@ __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
ADCON0 = 0                                  ' A/D off

;set varibles

signal VAR GPIO.3                           'GPIO.3 is used to the receiver
pulse  VAR BYTE                             'pulse is used to store the result
led var GPIO.0                              'GPIO.0 is the output we want to flash
i var byte                                  'i is used for the for next loop to generate width of pulses
getout var bit                              'used to check switch routines

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

main:
PulsIn signal, 1, pulse                     ' reads signal from receiver
IF (pulse >= 100) AND (pulse <= 160) Then   ' threshold for activation
Low GPIO.0                                  ' turns LED off
Else
goto flash                                  'if pulse is ouside range goto flash
EndIF
GoTo main                                   ' do it all again

flash:
for i = 1 to 254                            ' for next loop                                             
Pwm GPIO.0,i,1                              ' send pulse to GPIO.0 for lenght i increasing brightness
pause 1
if i=253 then                               ' test to see value of i
i=1                                         ' if test is true then set 1 to 1 and getout to 1
GetOut=1 
if Getout=1 then goto down                  ' if getout is q then jump to down routine
endif
next i

down:                                       ' same as flash but decreases brightness
for i = 254 to 1 step -1                                              
Pwm GPIO.0,i,1
pause 1
if i=2 then                                 ' test of value i, if i =1  then
i=1                                         ' set i to 1 and getout to 0
GetOut=0  
if Getout=0 then goto main                  ' test value of getout - if 0 go to start of program
endif
next i

[Kenjones1935]

Please, if you are interested, take a look at the
"How do I give a radio control car autonomous control"
Thread. I have a PICkit 2 and PICbasic programming package.

Attached is a sketch of what i need to do. I think. Any suggestions would be greatly appreciated. The forum does not let me attach the same file twice.

http://www.picbasic.co.uk/forum/atta...1&d=1263008711


Ken Jones

[ScaleRobotics]

For pulse width measurement, I ran across an interesting page.

http://www.mcmanis.com/chuck/robotic...e_measure.html

I borrowed a little bit of the code, and then added it to some DT_Interrupts. I am just measuring a servo pulse width, and sending raw tmr1 result to the serial port here, but you can change it to make it do other things. This was done with a PIC18f2520 in a LAB-X2. But the above gentleman used a PIC16F628, so it should be pretty flexible if you chose the corresponding DT_INTS include file. I would like to see more examples of pulse width measurement as well as pulse generation using interrupts, so if you have some, please share!

DEFINE OSC 20
DEFINE LOADER_USED 1         
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 42  ' 115200 Baud @ 20MHz, 0.94%
SPBRGH = 0
BAUDCON.3 = 1         ' Enable 16 bit baudrate generator

LED0 VAR portb.0
LED1 VAR portb.1
LED2 VAR portb.2

adcon1=15        ;sets all to digital
TRISA=%00000000                         ' Set PORTA  
TRISB=%01110000                         ' Set PortB
TRISC=%10000100                         ' Set PortC bit.2 for input (ccp) and bit.7 for ser input

INCLUDE "DT_INTS-18.bas"  ; Base Interrupt System
INCLUDE "sub16.inc"       ; subtract 16 bit macro
                   
LED0=0
LED2=0

risetime VAR WORD
falltime VAR WORD
falltime_l VAR falltime.Byte0
falltime_h VAR falltime.Byte1
risetime_l VAR risetime.Byte0
risetime_h VAR risetime.Byte1

ASM
INT_LIST  macro    ; IntSource,        Label,  Type, ResetFlag?
        INT_Handler   TMR0_INT,   ToggleLED0,   ASM,  yes
        INT_Handler    CCP1_INT,   PulseWidth,   ASM,  yes
    endm
    INT_CREATE               ; Creates the interrupt processor
ENDASM

T0CON = %10000100
T1CON = %00000001
T2CON = %00111101
CCP1CON = %00000101
@   INT_ENABLE  TMR0_INT      ; Enable Timer 0 Interrupts 
@   INT_ENABLE  CCP1_INT      ; Enable Capture Compare for pulse width measurement

Main:
    PAUSE 1000
    HSEROUT [DEC falltime,10]
GOTO Main

ASM
ToggleLED0
    btg  _LED0        ;blinky light
    INT_RETURN
ENDASM


ASM
PulseWidth
    BTFSS   CCP1CON, CCP1M0 ; Check for falling edge watch
    GOTO    FALL_EDGE       ; Go pick up the falling edge
    MOVF    CCPR1L,W        ; else store leading edge value
    MOVWF   _risetime_l         ; into 16 bit word risetime
    MOVF    CCPR1H,W
    MOVWF   _risetime_h
    BCF     CCP1CON, CCP1M0 ; Now capture the trailing edge
    GOTO    ISR_2           ; Exit the interrupt service routine
        
FALL_EDGE:
    BSF     CCP1CON, CCP1M0 ; Re-set for trailing edge capture
    MOVF    CCPR1L,W        ; Store the captured value into
    MOVWF   _falltime_l         ; falltime_l and ...
    MOVF    CCPR1H,W
    MOVWF   _falltime_h       ;             ... falltime_h
    ;
    ; 16 bit subtract 
    ;     falltime = falltime - risetime
    ;
    SUB16   _falltime, _risetime          ;this subroutine performs 16 bit subtraction
ISR_2
    INT_RETURN
ENDASM

[Kenjones1935]

You all posted code specifically for the 12F675. My PIC is a 16F887.

I am at a loss to translate from one PIC to the other. My PBP compiler (set up for 16F887) has no idea what to do with GPIO.x references. When I set it for 12F675 it is happy, but the resulting code is useless to my PICkit2.

Is it my job to read about the 12F675 and try to figure out which register in my 16F887 is equivalent? That would be an excellent homework assignment.

Ken

[tenaja]

Is it my job to read about the 12F675 and try to figure out which register in my 16F887 is equivalent? That would be an excellent homework assignment.

Well, yes... but it will take a whole lot longer to open the file than it will to hit ctrl-f and search for gpio.

[Kenjones1935]

I do not have all the necessary includes. Judging from the code snip offered by scalerobotics I need the base interrupt system for the 16 bit machines.

"INCLUDE "DT_INTS-18.bas" ; Base Interrupt System
INCLUDE "sub16.inc" ; subtract 16 bit macro"

I have a PICkit 2 with a 16F887.
Does a DT_INTS-16.BAS exist? Where?

ken

[ScaleRobotics]

I do not have all the necessary includes. Judging from the code snip offered by scalerobotics I need the base interrupt system for the 16 bit machines.

"INCLUDE "DT_INTS-18.bas" ; Base Interrupt System
INCLUDE "sub16.inc" ; subtract 16 bit macro"

I have a PICkit 2 with a 16F887.
Does a DT_INTS-16.BAS exist? Where?

ken

Hello Ken,

The DT_INTS-14.bas covers the PIC16 devices. The newest version 1.00 can be found here (at botom left). http://darreltaylor.com/DT_INTS-14/intro2.html The code should be able to be modified for your chip, but there are PIC chips with more timers, and more ccp pins out there.

It might be best to try out some of the ready made samples that Darrel gives, just to get the hang of using his interrupts, and making sure your includes, and configs are working.


I am working on a DT_INTS based RC servo passthrough (servo pulse measurement and pulse generation, but it is a little jittery right now, so I have try to trouble shoot that.