PBP projects for R/C models

[ScaleRobotics]

Scalerobotics,

How did you know of the contents of:
http://darreltaylor.com/DT_INTS-14/asm_ints.html
and
http://www.picbasic.co.uk/forum/show...39postcount=38

Is there a centralized resource?
Ken

I learned about them from the great folks on this forum. Without it, I couldn't do any of the things I think are pretty slick. Really, everything that I think is pretty amazing, was learned from reading, searching, and asking on this forum. Aside from the 222 page PicBasicPro manual, the forum is the most centralized resource that you will find.

I would agree with Alain, after reading the PBP manual and it's examples, the next best resource of examples is www.parallax.com site will have the best examples of basic. I have a Pic Basic Pro book that I hate, and I have browsed a few others that I dislike equally. Most are using examples of PIC16C devices and such that are older than my dog, and don't talk much on timers, interrupts, etc. I say save your money, and get the free examples that Parallax has in their documentation, and use this forum. Also read your manual from cover to cover two or three times. It will start to sink in, as you use the commands.

You can learn more about the DT_INTS by searching the forum. Besides Darrel's page, this is the only other source for information on how to use his interrupts.

[Kenjones1935]

As I said, the wheels go round, but...

The wheels are not going round and round in the pattern I expected. In particular they only go backwards. The code claims to sweep from 20% to 80% cuty cycle.

SOOO, can I use my USB connection and PICkit 2 Logic and Analyze Tool to see what is actually happening?

Ken

[ScaleRobotics]

I believe you are using the PWM example here: http://www.melabs.com/resources/samples/pbp/hardpwm.bas

This is a PWM that is not supposed to work with RC servo's. It's wave form is different. It is used to dim LED's etc. I am a little surprised that it can turn the wheels at all. I have a scope to help me view wave forms. I have tried for a few minutes to see what the pickit's logic tool can do, but I have not had any success. I am pretty sure it is just a problem with the operator (me).

[rmteo]

This is what the program header says:

' PicBasic Pro Program to demonstrate hardware PWM.
' Output is a 1Khz signal with duty cycle sweeping
' from 20% to 80% once per second

Since the frequency is 1KHz, its period is 1mS. The duty cycle is sweeping from 20% to 80% therefore the pulse width is varying from 0.2mS to 0.8mS. There are 2 problems here. For R/C signals, the period should be 20mS or 50Hz. Second, the pulse width should be 1.5mS for neutral, 1.0mS for extreme left (or full reverse) and 2.0mS for extreme right (or full forward). So your car is responding to a very short pulse (even less than full reverse). You have to modify the values in the program to get it to do what you expect.

[Kenjones1935]

Thanks gang.

I came to much the same conclusion myself. I have been trying to figure out what exactly this PWM code does so that I can modify it meet the RC specs. The comments in the program are fairly clear. My first attempts have not worked but I am optimistic.

Interesting how rusty my brain has become.

Ken

[Kenjones1935]

Here is the code that makes the wheels spin.

http://www.melabs.com/resources/samples/pbp/hardpwm.bas

There are no PBP commands that overtly make pulses. They are created by appropriately loading CCP1CON and CCPR1L. I found CCP1CON easily enough. It is listed in the INDEX of the 16F887 Data Sheet. CCPRxL and CCPRxH are not in INDEX. They are quietly mentioned on page 127. But why is there no HPWM command per page 86 in the PBP manual?


Although I see how this might be a low cpu overhead way to create PWM, I don't want to learn about this now. I want to use PBP and ASM commands to control my motor and servo. Maybe tomorrow all this will make sense.

Ken

[Kenjones1935]

The code in

http://www.melabs.com/resources/samples/pbp/hardpwm.bas

makes the wheels of my car go backwards in bursts. The bursts last, maybe 3/4 second then the wheels stop for a 1/4 second. I look at the code . I think that it is supposed to sweep through all pulse sizes in a second. I surmise the short ones are too short so the wheels don't move. As they get longer the come up near the low end of the electronic speed control spec. They start to move. Then the second is over.

I would like to pump PWM pulses out CCP1 that have a frequency of one every 20 msec (50 per second) and a pulse width that I can (by changing the code) vary from 1 msec to 2 msec. Am I correct in guessing that the frequency of the pulses is dictated by the PAUSE command. One pulse per loop through mainloop:

So far all my attempts have created no forward wheel motion at all! If one of you has the time please modify hardpwm.bas so that I understand it. Or, better yet, show me how to use PULSOUT. That does not work for me either.

Ken

[Kenjones1935]

I've got code that searches for "duty" that runs the motor. I have found the region that drives it backwards and that keeps it motionless. So far i have not found the forward moving pulse size, but it will not be long now.

Ken

[mackrackit]

A DC motor needs to have the polarity reversed to change the rotation???

[Kenjones1935]

Yes, DC motors need the polarity changed to change direction. I was led to believe that there is something magical in this electronic speed control that made it work differently. Thank you for reminding me to question assumptions.

Ken

[Kenjones1935]

If the electronic speed control does not reverse polarity as a function of pulse size, then I will need to use the technique Fritsl used in his wall hugging robot.

http://letsmakerobots.com/node/928

(which seems no longer available)

He cross wired the motor with multiple DPDT relay switches controlled by his PIC. I was going to copy that idea, but then I started believing the story of the magical ESC.

[mackrackit]

Hi Ken,
This may or may not be helpful, I think diagram "A" on page #3 might be to your fancy.
http://www.picbasic.co.uk/forum/atta...4&d=1228220843

[Acetronics2]

I would like to pump PWM pulses out CCP1 that have a frequency of one every 20 msec (50 per second) and a pulse width that I can (by changing the code) vary from 1 msec to 2 msec. Am I correct in guessing that the frequency of the pulses is dictated by the PAUSE command. One pulse per loop through mainloop:

CCP1 PWM @ 50 Hz ??? ... just read your Datasheet first !!!

NOW ... triggering the CCP1 module ( in compare mode ) @ 50 Hz ( from a timer ) looks much better ...

might be the PULSOUT could also do the trick for a CPU " locking time " of 2 ms ... if possible.

Now, a good program flow allows many, many things for R/C systems without using interrupts or peripherals ...

Alain

[Kenjones1935]

FATUBA manufactured the radio receiver in my RC car. It is the output of that box that I am trying to emulate coming out of my 16F887. They say here that reversing direction is done by controlling the PWM pulse size above or below 1.5ms. That is what I have been doing - I thought.

Attached is a quote from Electronic Control for DC Motors Using Discrete Bridge Circuits. It seems to say that my ESC should accept servo type PWM signals.

Is the output signal digital?

Output signals are ANALOG. Receivers vary by design on how they RECEIVE and ENCODE signals. But all deliver very similar output pulse signals, which is used to drive the servo to the desired location. This output pulse ranges from 1000uS to 2000uS, with 1500uS typically being center.
Is the output signal an on/off signal or does it have an internal regulator?

The output signal for each channel is a pulsed signal. The pulse width (commonly 1000uS to 2000uS) is determined by the corresponding channel of the transmitter. When activated by one of the proportional channels (such as elevator, aileron, throttle, rudder, or knob control) the pulse width will vary. This controls the servo movement. Most servos will be centered when the pulse is at 1500uS. Channels that are controlled by a switch (such as the gear channel) will operate the pulse width from two set values such as 1100uS when in one position and 1900uS when set to the other position to activate servo movement.
What signal does the receiver emit to differentiate forward or backward movement?

Direction of movement is determined by the direction in which the respective pulse is shifted off of center (neutral). Center being 1500uS, if the pulse is shifted above 1500uS, the direction of travel is one direction. If the pulse is shifted below 1500uS, the direction of travel is in the opposite direction.

[rmteo]

I gave you that info in post #44.

Since the frequency is 1KHz, its period is 1mS. The duty cycle is sweeping from 20% to 80% therefore the pulse width is varying from 0.2mS to 0.8mS. There are 2 problems here. For R/C signals, the period should be 20mS or 50Hz. Second, the pulse width should be 1.5mS for neutral, 1.0mS for extreme left (or full reverse) and 2.0mS for extreme right (or full forward). So your car is responding to a very short pulse (even less than full reverse). You have to modify the values in the program to get it to do what you expect.

[Kenjones1935]

Thank you all for your help. I posted those quotes because they back up what you have been saying and what I thought I coded.

Trouble is my PIC code only makes my car wheels go backwards and stop. I have not been able to create a PWM stream that drives the wheels forward. I know the ESC works because the wheels go fine under radio control.

Oscilloscope, here I come.

Ken

[ScaleRobotics]

Oscilloscope, here I come.

Great idea Ken. I don't know how much you have modified hardpwm.bas, but here it is in it's native form. First pic is about 20 percent, and second pic is about 80 percent (of a 1ms pulse):





You will notice that the min is about 0.2ms and max is 0.8ms.

Your servo or speed controller requires a pulse width between 1.0ms and 2.0ms. It would probably like to see these pulses every 20ms or so, not every 1 ms (as seen here).

And here is what you want it to look like (from my rc receiver):

[Kenjones1935]

The pictures you attached match my mental picture of what I have created. First I modified the .bas to make consistant 1.35ms pulses. The PAUSE command creates the spacing in time. This drove the car quite fast backwards with no hesitations. Next 1.5ms. The wheels stopped. From that point I increased (not automatically) the pulse width up past 2ms to no avail. I never got the car wheels to turn forward.

Where can I find the assembly language code for the Basic commands?

I gather from reading the manual that PAUSE is not a pure interrupt driven behavior. I can not use that command if it shuts down the PIC between pulses.

I have two plans.

1. Study Assembly Language programming. I do not see enough explanation in the PBP manual to feel confident in what Basic Pro is actually doing. I should be able to get the PIC to better communicate to me what it is doing via the LED's.

2. Attach CCP1 to the servo that steers the car instead of the drive wheels. I know what a servo is and I know this one works.

3. Make the effort to find an oscilloscope. My only access at this time is the CS department at Fitchburg State College. I would rather not use them. I do not really know them that well.

Ken

[ScaleRobotics]

First I modified the .bas to make consistant 1.35ms pulses. The PAUSE command creates the spacing in time.

The "Pause 17" lets you adjust how fast it moves from 20% and 80%. However, it does not adjust the pulse width, which is what you need to be adjusting. I can't explain why it works at all though, but it might be so confused from receiving pulses every 1ms, instead of every 20ms.

Where can I find the assembly language code for the Basic commands?

I suppose MeLabs could have just given us all the assembly code, but that probably does not make good business sense for the company. You can TRY to read some of the assembled code after you compile, but it looks a little jiberish. It is nameofyourfile.lst . Some people have suggested getting a dis-assembler, and disassemble the hex file ... but then I think you loose syntax then.

I gather from reading the manual that PAUSE is not a pure interrupt driven behavior. I can not use that command if it shuts down the PIC between pulses.

In my mind, an interrupt is better, as it will not stall your processing. Pauses can work well with servo's. I have not tried them much with motor controllers. The fact that the pulse code you were using sort of worked is encouraging for simplifying code, and staying away from interrupts.

I have two plans.

1. Study Assembly Language programming. I do not see enough explanation in the PBP manual to feel confident in what Basic Pro is actually doing. I should be able to get the PIC to better communicate to me what it is doing via the LED's.

2. Attach CCP1 to the servo that steers the car instead of the drive wheels. I know what a servo is and I know this one works.

3. Make the effort to find an oscilloscope. My only access at this time is the CS department at Fitchburg State College. I would rather not use them. I do not really know them that well.

I count three plans ..... here is my personal take on them which might be worth less than two cents...

Your plan 1 is for someone that really wants to learn all about each register and each bit, and what they control. This will require reading a lot of the 375 page datasheet. Picbasic takes care of a lot of these details for you, making it easier for most people to create useful projects in a much smaller amount of time. Yes, it masks many of these processes from you, but to me, this is a very good thing!

Plan 2, good idea. I still do not think you are really creating 1.5ms pulses. Why don't you PM me your code, or post it here, and I will PM you back, or post here what I see on my scope using your code.

Plan 3 See above.

Why don't you try this code, just don't use the analog. Change pos value to change servo, or motor controller. It will give you an idea if it only does servo's or if your motor controller will like it.

EDIT:

Ok this code http://www.melabs.com/resources/samp...bp/servox2.bas

[Kenjones1935]

I am realizing that using PAUSE can not work if my PIC is meant to do some thinking between pulses. I just discovered

http://darreltaylor.com/DT_INTS-14/SPWM.html

He is using interrupts. That is what I was hoping to do in the first place. I'll see if I can figure out what he is saying.

Meanwhile, would you be willing to take pictures of the pulses that my code is making if I posted the code?

Ken

[ScaleRobotics]

Sure! Post what you have, and I will send you some oscilloscope shots.

[Kenjones1935]

Scalerobotics:

This snippet has the capabiltiy to increment the pulse size a little bit at a time.

With this code the car starts out driving very fast backwards, then after five to ten seconds it stops, but never starts up forward.

My theory is that the (PAUSE 20) is what is causing the 50 pulses per second, Is that correct?

duty	VAR	WORD		' Duty cycle value (CCPR1L:CCP1CON<5:4>)
range   VAR word
segment   var word 
		TRISC.2 = 0				' Set PORTC.2 (CCP1) to output
		CCP1CON = %00001100		' Set CCP1 to PWM 
		T2CON = %00000101		' Turn on Timer2, Prescale=4

' Use formula to determine PR2 value for a 1KHz signal, 
' 4MHz clock, and prescale=4. (4E6/(4*4*1E3))-1=249
'		PR2 = 249				' Set PR2 to get 1KHz out
'		PR2 = 499				' Set PR2 to get 2KHz out
	
' Use formula to determine CCPR1L:CCP1CON<5:4> value for
' ends of range 20% to 80%.  (249+1)*4*0.2=200 (20% value)
' (249+1)*4*0.8=800 (80% value)
'       duty = 200	' Set duty cycle to 20%

       range = 25
       duty = 1650	' Set duty cycle to 1.65msec      
       segment = 0

mainloop:	CCP1CON.4 = duty.0		' Store duty to registers as
		CCP1CON.5 = duty.1		' a 10-bit word
		CCPR1L = DUTY >> 2
		Pause 20				' Pause 1/50 of second
       duty = duty + 2    ' Increase duty cycle




		IF (duty < (1650 + segment + range)) Then mainloop	' Do it again unless 2 msec

		duty = duty + 2				' Reset to 20% duty cycle

		segment = segment + range
        
        PAUSE 2000      'Pause 2 seconds				
        
       	GoTo mainloop				' Do it forever

[ScaleRobotics]

Here is the result. It changes from off through the percentage points to all the way on, but the period remains constant at about 1.023ms. (I finally got my oscilloscope USB driver to work today!)

[Kenjones1935]

Thank you soooo much. What a great tool..

Two things for me to consider.

1. PAUSE seems to not have the affect I expected.
2. The PR2 constant must mean something to PBP, but I can not figure out what.

Lastly, which version of oscilloscope software do you use? Is it freeware or did it cost money. If so, how much?

Ken

[Kenjones1935]

The following code makes the car go full speed backwards, then stop, then full speed forwards, then stop etc. Using the RC system I can control the motor continuously though varying speed. I have not yet figured what HPWM parameters produce various speeds to the ESC. It may be that the over-specification fast pulse frequency is overriding that nuance.

To really discover what this is doing I need to study and understand the ASM code. I think HPWM is interrupt driven. I am concerned because page 87 of the PBP Manual seems to say that the slowest pulse frequency is 245 hz. I want 50 hz.

'****************************************************************
'*  Name    : HPWMcommand.BAS                                   *
'*  Author  : Ken Jones                                         *
'*  Notice  : Copyright (c) 2010 [select VIEW...EDITOR OPTIONS] *
'*          : All Rights Reserved                               *
'*  Date    : 1/27/2010                                         *
'*  Version : 1.0                                               *
'*  Notes   : PBP has a HPWM command.  Let's try it.                                                  *
'*          :                                                   *
'****************************************************************
' Don't forget. The duty cycle is 0 to 256 resolution
MAINLOOP:
  HPWM 1,110,50     ' Neutral discovered by experiment.
  PAUSE 5000
  HPWM 1,64,50      ' Full backwards
  PAUSE 2000
  HPWM 1,110,50
  PAUSE 5000
  HPWM 1,164,50     ' Full forward
  PAUSE 2000
 goto mainloop

Ken

[rmteo]

....I am concerned because page 87 of the PBP Manual seems to say that the slowest pulse frequency is 245 hz. I want 50 hz.

Period = [(PR2) + 1] * 4 * TOSC *(TMR2 Prescale Value)
Frequency = 1/Period

Therefore with a 4MHz clock, the lowest frequency is 244Hz.

[Kenjones1935]

I think I am being told that HPWM can not do the job that I need done. Who has a suggestion?

[ScaleRobotics]

I think I am being told that HPWM can not do the job that I need done. Who has a suggestion?

Did you just open the floor to my broken record again?! Here is my view, but I agree, you (we all) need to hear more viewpoints than mine.

Darrel Taylor Interrupts using TMR0 for pulse width, and TMR2 for 20ms period, and receiver pulse width sensing with CCP1_INT and TMR1. Your chip has them, just need to utilize them.

If you always have an RC receiver on, then you can use that as your time base for 20ms. So, you could use the CCP1_INT to read the pulse width coming from the receiver. (This will use TMR1). Then you could use TMR0, or TMR2 for the pulse width. Every time you calculated the pulse from your CCP1_INT, you would send out your servo pulse on whatever pin you like, or control multiple pins, using the same timer.

You really just need to start playing around with these timers and interrupts, and pulse some pins to get your head around it. But without a scope, it will be pretty difficult in my opinion.

Here some scope info that you asked me about. It is a stand alone, but has a USB port and free software that comes with it. It cost just under $300.00. http://picbasic.co.uk/forum/showthread.php?t=12483

[rmteo]

Ken,

Can you do a LED blinky without using PAUSE (or any other delay commands)? Try to do a 1 second blinky using a timer. When you can do that, you will be well on your way to solving your motor ESC problem.

[Kenjones1935]

Guys and maybe Gals,

I am getting frustrated. I can not find the documentation that I need. I need Assembler Language details for the 16-bit chips. I need 16-bit BASIC libraries (Microchip talks C, not Basic). Darrel Taylor is rebuilding his site. He is not accepting new members.

Microchip has screwed up on this link:

MPLAB Assembler, Linker and Utilities for 16-Bit Devices User's Guide
which points to-->
http://ww1.microchip.com/downloads/e...Doc/51317G.pdf

But when you download51317G you discover it is about the 24-BIt devices. It is the same document that -->

DS51317 - MPLAB Assembler, Linker and Utilities for PIC24 MCUs and dsPIC DSCs User's Guide

points to.

What is the number for the 16-Bit devices user's guide?? I have not found a complete list of Assembly language code, syntax, structure whatever! Without that I do not see how I can understand what this 16F887 is doing.

Also it is late. I am going to bed.

Ken

[mackrackit]

Ken,

Darrel's site must have been down for what evere reason. It seems to work now.
http://www.PBPgroup.com/

ASM instuctions are normally in the devices data sheet. But... Please do not take this the wrong way. If you are having trouble with Basic I doubt it ASM will do much good.

I like remto's sugesstion about blinky. Give that a shot.

[rmteo]

Firstly, your PIC16F887 is a 14-bit core device and the ASM manual is here MPASM™ Assembler, MPLINK™ Object
Linker MPLIB™ Object Librarian User’s Guide

Next thing you really need to download is the data sheet PIC16F887

Also, download this FREE book and read it to understand how a PIC works PIC Microcontrollers

The last one is the most useful - I pointed this out to you in an earlier post.

[mackrackit]

Ken,
I do not know anything about RC stuff, but here is something to play with.

<font color="#000080"><i>'16F887 INT RUPT
'44 PIN DEMO BOARD
   </i></font>@ <font color="#0000FF"><b>__config _CONFIG1</b></font>, <font color="#0000FF"><b>_INTRC_OSC_NOCLKOUT </b></font>&amp; <font color="#0000FF"><b>_WDT_ON </b></font>&amp; <font color="#0000FF"><b>_MCLRE_OFF </b></font>&amp; <font color="#0000FF"><b>_LVP_OFF </b></font>&amp; <font color="#0000FF"><b>_CP_OFF
   INTCON</b></font>.<font color="#800000"><b>5 </b></font>= <font color="#800000"><b>1    </b></font><font color="#000080"><i>'ENABLE TMR0  DATA SHEET SECTION 14.3.2
   </i></font><font color="#0000FF"><b>OSCCON </b></font>= <font color="#800000"><b>%01110000 </b></font><font color="#000080"><i>'8 Mhz
   </i></font><font color="#0000FF"><b>OPTION_REG </b></font>= <font color="#800000"><b>%10000111  </b></font><font color="#000080"><i>' 1:256 PRESCALE
   </i></font><font color="#FF0000"><b>ON INTERRUPT GOTO </b></font><font color="#0000FF"><b>TLOOP
   CNT  </b></font><font color="#FF0000"><b>VAR BYTE
   </b></font><font color="#0000FF"><b>D    </b></font><font color="#FF0000"><b>VAR BYTE
   </b></font><font color="#0000FF"><b>D </b></font>= <font color="#800000"><b>0
   
   </b></font><font color="#0000FF"><b>START</b></font>:
   <font color="#FF0000"><b>FOR </b></font><font color="#0000FF"><b>CNT </b></font>= <font color="#800000"><b>0 </b></font><font color="#FF0000"><b>TO </b></font><font color="#800000"><b>150
   </b></font><font color="#FF0000"><b>PWM </b></font><font color="#0000FF"><b>PORTD</b></font>.<font color="#800000"><b>7</b></font>,<font color="#0000FF"><b>D</b></font>,<font color="#800000"><b>100
   </b></font><font color="#0000FF"><b>D </b></font>= <font color="#0000FF"><b>D </b></font>+ <font color="#800000"><b>2
   </b></font><font color="#FF0000"><b>NEXT </b></font><font color="#0000FF"><b>CNT
   </b></font><font color="#FF0000"><b>GOTO </b></font><font color="#0000FF"><b>START
   
   </b></font><font color="#FF0000"><b>DISABLE
   </b></font><font color="#0000FF"><b>TLOOP</b></font>:
   <font color="#0000FF"><b>INTCON</b></font>.<font color="#800000"><b>2</b></font>=<font color="#800000"><b>0 </b></font><font color="#000080"><i>' DATA SHEET SECTION 14.3.2
   </i></font><font color="#FF0000"><b>TOGGLE </b></font><font color="#0000FF"><b>PORTD</b></font>.<font color="#800000"><b>4
   </b></font><font color="#FF0000"><b>RESUME
   ENABLE
</b></font>

[mackrackit]

http://www.picbasic.co.uk/forum/showthread.php?t=222
Might also help??

[ScaleRobotics]

I had earlier success in getting a servo pulse width to be smooth on a Pic18F2520. But I am now trying to make DT_INTS servo pulse width for a PIC12F683. I have it sweeping from about .95ms to 1.9 ms, but it is not smooth at all. In fact, on the scope, it sometimes switches direction (starts to get wider instead of narrower for a fraction of a second). It is pretty darn ugly in fact.

Any ideas what I might have done (or not done) to cause this?

PIC12f683

</i></font><b>DEFINE </b>OSC 8
<b>INCLUDE </b><font color="#FF0000">&quot;DT_INTS-14.bas&quot; </font><font color="#000080"><i>;interrupt routines
</i></font><b>INCLUDE </b><font color="#FF0000">&quot;sub16.inc&quot;       </font><font color="#000080"><i>; subtract 16 bit macro

</i></font><b>DEFINE </b>DEBUG_REG	GPIO
<b>DEFINE </b>DEBUG_BIT	0

<b>DEFINE </b>DEBUGIN_BIT	1
<b>DEFINE </b>DEBUG_BAUD	38400
<b>DEFINE </b>DEBUG_MODE	0

INTCON = %10101000 <font color="#000080"><i>'internal oscillator
</i></font>OSCCON = %01110000 <font color="#000080"><i>'set for 8mhz internal
</i></font>CMCON0 = 7 <font color="#000080"><i>'TURN COMPARITORS OFF
</i></font>TRISIO = %010000 <font color="#000080"><i>'Set GSIO 4 INPUT, others to OUTPUT
</i></font>OPTION_REG = %11000010
T1CON = %01000001
T2CON = %01001110
servo <b>VAR </b>GPIO.2
servo = 0
pulse <b>VAR BYTE

</b>pulse = 0
bittest <b>VAR BIT

ASM
</b><font color="#008000">INT_LIST  macro    </font><font color="#000080"><i>; IntSource,        Label,  Type, ResetFlag?
        </i></font><font color="#008000">INT_Handler   TMR0_INT,   PulseOut,   ASM,  yes
        INT_Handler   TMR2_INT,   period,     ASM,  yes
        INT_Handler   TMR1_INT,   test,       ASM,  yes
    endm
    INT_CREATE               </font><font color="#000080"><i>; Creates the interrupt processor

    </i></font><font color="#008000">INT_ENABLE  TMR0_INT     </font><font color="#000080"><i>; Enable pulseout interrupts  
    </i></font><font color="#008000">INT_ENABLE  TMR2_INT     </font><font color="#000080"><i>; enable period interrupt (20ms)
    </i></font><font color="#008000">INT_ENABLE  TMR1_INT     </font><font color="#000080"><i>; enable interrupt to increment pulse width (test)
</i></font><b>ENDASM

</b>Main:
    nop
<b>GOTO </b>Main

<font color="#000080"><i>'---[TMR0_INT - interrupt handler]------------------------------------------

</i></font><b>ASM
</b><font color="#008000">PulseOut
    btfsc _bittest      </font><font color="#000080"><i>;test status of bittest bit
    </i></font><font color="#008000">goto $+7            </font><font color="#000080"><i>;if high skip 7 lines
    </i></font><font color="#008000">bcf OPTION_REG,5    </font><font color="#000080"><i>;stop timer
    </i></font><font color="#008000">movf _pulse,w       </font><font color="#000080"><i>;load TMR0 with value of pulse variable
    </i></font><font color="#008000">movwf TMR0
    bsf _bittest        </font><font color="#000080"><i>;set bittest bit, indicating we are on second half
    </i></font><font color="#008000">bsf OPTION_REG,5    </font><font color="#000080"><i>;start timer again for second interrupt
    </i></font><font color="#008000">goto $+3            </font><font color="#000080"><i>;skip to return from interrupt
    </i></font><font color="#008000">bcf OPTION_REG,5    </font><font color="#000080"><i>;stop timer
    </i></font><font color="#008000">bcf _servo          </font><font color="#000080"><i>;bring servo pin low for end of pulse width
    </i></font><font color="#008000">INT_RETURN

</font><b>ENDASM
</b><font color="#000080"><i>'---[TMR2_INT - interrupt handler]------------------------------------------
</i></font><b>ASM
</b><font color="#008000">period
    bsf _servo          </font><font color="#000080"><i>;set servo pin high (begin pulse width)
    </i></font><font color="#008000">movlw d'0'          </font><font color="#000080"><i>;set timer0 to 0 (full length of timer)
    </i></font><font color="#008000">movwf TMR0    
    bsf OPTION_REG,5    </font><font color="#000080"><i>;start timer0, now PulseOut interrupt will occur
    </i></font><font color="#008000">bcf _bittest        </font><font color="#000080"><i>;clear bittest bit
    </i></font><font color="#008000">INT_RETURN
</font><b>ENDASM
</b><font color="#000080"><i>'---[TMR1_INT - interrupt handler]------------------------------------------
</i></font><b>ASM
</b><font color="#008000">test 
    incf _pulse
    INT_RETURN
</font><b>ENDASM

</b></code></pre><!--EndFragment--></body>
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[Acetronics2]

Hi,

I remember some batches of 12F683 did not like the duty value to be changed " on the fly " and needed to stop and restart the CCP module.

Was written on the µChip datasheet ( prior to D release )...

I think some lines about it exist on this forum.


But you don't use the CCP module ...

What I see more is you want to stop Timer0

bcf OPTION_REG,5    ;stop timer

Option.5 is the TOCS bit ... and that's not a good thing to switch clock to TockI pin ...

Alain

[ScaleRobotics]

Thanks Alain, that was it!

I changed those to:

bsf INTCON,5        ;enable timer0 interrupt

and 

bcf INTCON,5        ;disable timer0 interrupt

and now the pulse runs smoothly. Only I don't get the initial set timer0 to 0, then add the second half of pulse width. I only get the second half where TMR0=pulse. So pulse width is between 0 and 1ms.

But I will work on that!

Thanks again,

Walter

[Kenjones1935]

Thank you for setting me straight on which document is which.

DS33014K is just what I have been looking for.

Tuesday Darrel Taylor's site said that it was under construction and that it would not accept new membership.

I have coded in C and in Assembly. More recently in shell and tcl. I never had a reason to use Basic as none of my professional work used a PC.

I think this 33014 will get me started.

Scalerobotics, if you get a chance see if you can record the radio receiver output signals for the other channels. In particular one which is just ON-OFF from the point of view of the transmitter.

Ken - thanks gang.

[rmteo]

Ken,

....ASM instuctions are normally in the devices data sheet. But... Please do not take this the wrong way. If you are having trouble with Basic I doubt it ASM will do much good.

I like remto's sugesstion about blinky. Give that a shot.

Ken, I highly recommend taking Dave's advise. You need a better understanding of what makes a PIC tick (hint, read the free book I linked to). When you have that under your belt, then the coding is the really easy part. It doesn't matter whether you use C, BASIC (PBP or some other variant) or ASM - the situation is the same.

[ScaleRobotics]

Here is some code that will measure an RC receiver pulse width coming in on GPIO.2, perform a little math on the value, and put out the wave form out on GPIO.1, using DT Interrupts.

It's on a little 12F683 and was written for 8mhz internal. Looks pretty good on the scope. I need to test it on a motor controller though. But time for bed.....

<html>
<head></head>
<body><!--StartFragment--><pre><code><font color="#000080"><i>
</i></font><b>DEFINE </b>OSC 8
<b>INCLUDE </b><font color="#FF0000">&quot;DT_INTS-14.bas&quot;</font><font color="#000080"><i>;interrupt routines
</i></font><b>INCLUDE </b><font color="#FF0000">&quot;sub16.inc&quot;     </font><font color="#000080"><i>; subtract 16 bit macro

</i></font><b>DEFINE </b>DEBUG_REG	GPIO
<b>DEFINE </b>DEBUG_BIT	0
<b>DEFINE </b>DEBUGIN_BIT	1

<b>DEFINE </b>DEBUG_BAUD	38400
<b>DEFINE </b>DEBUG_MODE	0

INTCON = %10101000      <font color="#000080"><i>'
</i></font>OSCCON = %01110000      <font color="#000080"><i>'set for 8mhz internal
</i></font>CMCON0 = 7              <font color="#000080"><i>'TURN COMPARITORS OFF
</i></font>ANSEL  = %00000000      <font color="#000080"><i>'Set A/D OFF
</i></font>ADCON0 = %00000000      <font color="#000080"><i>'Analog converter OFF 
</i></font>TRISIO = %010100        <font color="#000080"><i>'Set GSIO 4 and 2 to INPUT, others to OUTPUT
</i></font>OPTION_REG = %11000010
T1CON  = %00110001
T2CON  = %01001110
CCP1CON = %00000101

risetime <b>VAR WORD       </b><font color="#000080"><i>;used for pulse width measure start of pw

</i></font>falltime <b>VAR WORD       </b><font color="#000080"><i>;time at end of pulse width
</i></font>falltime_l <b>VAR </b>falltime.Byte0
falltime_h <b>VAR </b>falltime.Byte1
risetime_l <b>VAR </b>risetime.Byte0
risetime_h <b>VAR </b>risetime.Byte1
pulsewidth <b>VAR WORD
</b>pulsewidth_l <b>VAR </b>pulsewidth.Byte0
pulsewidth_h <b>VAR </b>pulsewidth.Byte1

ServoOut <b>VAR </b>GPIO.1
ServoOut = 0
pulse <b>VAR BYTE

</b>TMR0 = 0
pulse = 255
bittest <b>VAR BIT

ASM
</b><font color="#008000">INT_LIST  macro    </font><font color="#000080"><i>; IntSource,        Label,  Type, ResetFlag?
        </i></font><font color="#008000">INT_Handler   TMR0_INT,   PulseOut,   ASM,  yes
        INT_Handler   TMR2_INT,   period,     ASM,  yes
        INT_Handler   CCP1_INT,   PWMeasure,  ASM,  yes
    endm
    INT_CREATE               </font><font color="#000080"><i>; Creates the interrupt processor

    </i></font><font color="#008000">INT_ENABLE  TMR0_INT     </font><font color="#000080"><i>; Enable pulseout interrupts  
    </i></font><font color="#008000">INT_ENABLE  TMR2_INT     </font><font color="#000080"><i>; enable period interrupt (20ms)
    </i></font><font color="#008000">INT_ENABLE  CCP1_INT     </font><font color="#000080"><i>; enable interrupt to increment pulse width (test)
</i></font><b>ENDASM
    PAUSE </b>200
Main:
    <b>PAUSE </b>20
    <font color="#000080"><i>;debug dec pulsewidth,&quot; &quot;,10,13
    </i></font>pulse = ((pulsewidth * 8)/10)-167 <font color="#000080"><i>;scale to fit into a byte
    </i></font>pulse = 255 - pulse               <font color="#000080"><i>;reverse the stick 
    

</i></font><b>GOTO </b>Main

<font color="#000080"><i>'---[TMR0_INT - interrupt handler]------------------------------------------

</i></font><b>ASM
</b><font color="#008000">PulseOut
    btfsc _bittest      </font><font color="#000080"><i>;test status of bittest bit
    </i></font><font color="#008000">goto $+7            </font><font color="#000080"><i>;if high skip 7 lines
    </i></font><font color="#008000">bcf INTCON,5        </font><font color="#000080"><i>;stop timer
    </i></font><font color="#008000">movf _pulse,w       </font><font color="#000080"><i>;load TMR0 with value of pulse variable
    </i></font><font color="#008000">movwf TMR0
    bsf _bittest        </font><font color="#000080"><i>;set bittest bit, indicating we are on second half
    </i></font><font color="#008000">bsf INTCON,5        </font><font color="#000080"><i>;start timer again for second interrupt
    </i></font><font color="#008000">goto $+3            </font><font color="#000080"><i>;skip to return from interrupt
    </i></font><font color="#008000">bcf INTCON,5        </font><font color="#000080"><i>;stop timer
    </i></font><font color="#008000">bcf _ServoOut       </font><font color="#000080"><i>;bring ServoOut pin low for end of pulse width
    </i></font><font color="#008000">INT_RETURN



</font><b>ENDASM
</b><font color="#000080"><i>'---[TMR2_INT - interrupt handler]------------------------------------------
</i></font><b>ASM
</b><font color="#008000">period
    movlw d'72'          </font><font color="#000080"><i>;fine tune timer2 period
    </i></font><font color="#008000">movwf TMR2    
    bcf INTCON,2         </font><font color="#000080"><i>;clear timer flag if set
    </i></font><font color="#008000">movlw d'17'          </font><font color="#000080"><i>;set timer0 first 1ms time base
    </i></font><font color="#008000">movwf TMR0    
    bsf INTCON,5         </font><font color="#000080"><i>;enable timer0 interrupt 
    </i></font><font color="#008000">bsf _ServoOut        </font><font color="#000080"><i>;set ServoOut pin high (begin pulse width)
    </i></font><font color="#008000">bcf _bittest
    INT_RETURN
</font><b>ENDASM
</b><font color="#000080"><i>'---[CCP1_INT - interrupt handler]------------------------------------------
</i></font><b>ASM

</b><font color="#008000">PWMeasure

    BTFSS   CCP1CON, CCP1M0 </font><font color="#000080"><i>; Check for falling edge watch
    </i></font><font color="#008000">GOTO    FALL_EDGE       </font><font color="#000080"><i>; Go pick up the falling edge
    </i></font><font color="#008000">MOVF    CCPR1L,W        </font><font color="#000080"><i>; else store leading edge value
    </i></font><font color="#008000">MOVWF   _risetime_l         </font><font color="#000080"><i>; into 16 bit word risetime
    </i></font><font color="#008000">MOVF    CCPR1H,W
    MOVWF   _risetime_h
    BCF     CCP1CON, CCP1M0 </font><font color="#000080"><i>; Now capture the trailing edge
    </i></font><font color="#008000">GOTO    ISR_2           </font><font color="#000080"><i>; Exit the interrupt service routine
        
</i></font><font color="#008000">FALL_EDGE:
    BSF     CCP1CON, CCP1M0 </font><font color="#000080"><i>; Re-set for trailing edge capture
    </i></font><font color="#008000">MOVF    CCPR1L,W        </font><font color="#000080"><i>; Store the captured value into
    </i></font><font color="#008000">MOVWF   _falltime_l         </font><font color="#000080"><i>; falltime_l and ...
    </i></font><font color="#008000">MOVF    CCPR1H,W
    MOVWF   _falltime_h       </font><font color="#000080"><i>;             ... falltime_h
    ;
    ; 16 bit subtract 
    ;     falltime = falltime - risetime
    ;
    </i></font><font color="#008000">SUB16   _falltime, _risetime   </font><font color="#000080"><i>;do 16 bit subtraction to find width
    </i></font><font color="#008000">movf _falltime_l,w
    movwf _pulsewidth_l
    movf _falltime_h,w
    movwf _pulsewidth_h
ISR_2
    INT_RETURN


</font><b>ENDASM


</b></code></pre><!--EndFragment--></body>
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