PBP projects for R/C models

[mackrackit]

How'd that work out for you?

Worked well until I pulled up to the checkpoint doing it. Thought they were going to take me to secondary...

Ken,
Here is code using DT's INTs giving an interrupt at 200 Hz.
All I did was tweak Darrel's blinky example.

<font color="#008000"><b><i>'FL PIC16F887
'16F887 DT INT RUPT
'44 PIN DEMO BOARD

'REMOVE THIS LINE IF NOT SETTING THE CONFIGS IN CODE SPACE
</i></b>@ __config _CONFIG1, _INTRC_OSC_NOCLKOUT &amp; _WDT_ON &amp; _MCLRE_OFF &amp; _LVP_OFF &amp; _CP_OFF
</font><font color="#0000FF"><b>OSCCON </b></font>= <font color="#800000"><b>%01100000 </b></font><font color="#008000"><b><i>'4 Mhz
</i></b></font><font color="#FF0000"><b>DEFINE </b></font><font color="#0000FF"><b>OSC </b></font><font color="#800000"><b>4

</b></font><font color="#0000FF"><b>LED1    </b></font><font color="#FF0000"><b>VAR </b></font><font color="#0000FF"><b>PORTD</b></font>.<font color="#800000"><b>4
</b></font><font color="#0000FF"><b>wsave </b></font><font color="#FF0000"><b>VAR BYTE </b></font><font color="#800000"><b>$70 </b></font><font color="#0000FF"><b>SYSTEM
</b></font><font color="#FF0000"><b>INCLUDE </b></font><b><i>&quot;DT_INTS-14.bas&quot;     </i></b><font color="#008000"><b><i>' Base Interrupt System
</i></b></font><font color="#FF0000"><b>INCLUDE </b></font><b><i>&quot;ReEnterPBP.bas&quot;     </i></b><font color="#008000"><b><i>' Include if using PBP interrupts

</i></b></font><font color="#FF0000"><b>ASM
</b></font><font color="#008000">INT_LIST  macro    <b><i>; IntSource,        Label,  Type, ResetFlag?
        </i></b>INT_Handler   TMR1_INT,  _ToggleLED1,   PBP,  yes
    endm
    INT_CREATE               <b><i>; Creates the interrupt processor
</i></b></font><font color="#FF0000"><b>ENDASM
</b></font><font color="#008000"><b><i>'5.0 mSec OR 200 Hz INTERRUPTS
</i></b></font><font color="#0000FF"><b>T1CON </b></font>= <font color="#800000"><b>%00000001         </b></font><font color="#008000"><b><i>'Prescaler = 1:1, TMR1ON
'PRELOAD 60543
</i></b></font><font color="#0000FF"><b>PreLoad     </b></font><font color="#FF0000"><b>VAR WORD
</b></font><font color="#0000FF"><b>PreLoad </b></font>=  <font color="#800000"><b>60543
</b></font><font color="#0000FF"><b>TMR1L </b></font>= <font color="#0000FF"><b>PreLoad</b></font>.<font color="#0000FF"><b>LowByte
TMR1H </b></font>= <font color="#0000FF"><b>PreLoad</b></font>.<font color="#0000FF"><b>HighByte
</b></font><font color="#008000">@ INT_ENABLE  TMR1_INT     <b><i>; enable Timer 1 interrupts

</i></b></font><font color="#0000FF"><b>Main</b></font>:      <font color="#008000"><b><i>'DO WHATEVER YOU WANT HERE
  </i></b></font><font color="#FF0000"><b>PAUSE </b></font><font color="#800000"><b>1000
  </b></font><font color="#FF0000"><b>HIGH </b></font><font color="#0000FF"><b>PORTD</b></font>.<font color="#800000"><b>7
  </b></font><font color="#FF0000"><b>PAUSE </b></font><font color="#800000"><b>1000
  </b></font><font color="#FF0000"><b>LOW </b></font><font color="#0000FF"><b>PORTD</b></font>.<font color="#800000"><b>7
</b></font><font color="#FF0000"><b>GOTO </b></font><font color="#0000FF"><b>Main

</b></font><font color="#008000"><b><i>'---[TMR1 - interrupt handler]--------------------------------------------------
</i></b></font><font color="#0000FF"><b>ToggleLED1</b></font>:
     <font color="#FF0000"><b>TOGGLE </b></font><font color="#0000FF"><b>LED1
     </b></font><font color="#FF0000"><b>TOGGLE </b></font><font color="#0000FF"><b>PORTC</b></font>.<font color="#800000"><b>6    </b></font><font color="#008000"><b><i>'CONNECTED TO METER
     </i></b></font><font color="#0000FF"><b>TMR1L </b></font>= <font color="#0000FF"><b>PreLoad</b></font>.<font color="#0000FF"><b>LowByte   </b></font><font color="#008000"><b><i>' Load the timer with preload value.
     </i></b></font><font color="#0000FF"><b>TMR1H </b></font>= <font color="#0000FF"><b>PreLoad</b></font>.<font color="#0000FF"><b>HighByte
</b></font><font color="#008000">@ INT_RETURN
</font>

[cncmachineguy]

Hi Ken, Just looked over section 6. I always think about the prescaler like this:

With no prescaler, timer increments as I posted earlier, Every 4 counts of the ocs will inc the timer by 1. If you have prescale set to 2, timer will inc every 8 counts, or half as fast. set to 4 it will inc every 16 counts or 1/4 speed, and set to 8, timer will inc every 32 counts or 1/8 speed. does this make sense?

So in summary, the prescaler is really a clock divider for the timer.

[cncmachineguy]

Quick question, how did you determine the preload value? I mean to say, I understand what it represents, just how did you determine the offset?

[mackrackit]

I cheated
http://www.picbasic.co.uk/forum/cont....-PICMultiCalc

[Kenjones1935]

Not much luck reading DT_INTS-14. I do not understand ASM and all the macros that have been written.

Soooo I installed the two blinky programs and they both looked correct. I activated the LOGIC TOOL from PICKIT2 and looked carefully at the 20millisec square wave. Close enough for government work. Next I changed the

TOGGLE PORTC.6 'CONNECTED TO METER

command to

PWM PORTD.7, 127, 1

and hooked up Channel 2 of the LOGIC TOOL to PORTD.7.

I expected to see a single pulse every 20millisec. I even hoped that the pulse would be 1.5millisec long.

I see many pulses seemingly not related to the edges of the interrupt driven 50Hz square wave. I would show you all a picture, but my FastStone Capture is screwed up.

Is there any PWM-like command that makes one pulse ranging from 1millisec to 2millisec in 256 gradations?

Ken

[mackrackit]

carefully at the 20millisec square wave

That is odd, I must have something off...

Is there any PWM-like command that makes one pulse ranging from 1millisec to 2millisec in 256 gradations?

The PULSOUT command might do the trick?

[Kenjones1935]

Here is what my LOGIC TOOL displays. The only change in the code is this substitution of a PWM command.

ToggleLED1:
     TOGGLE LED1
     PWM PORTD.7,127,1
     TMR1L = PreLoad.LowByte   ' Load the timer with preload value.
     TMR1H = PreLoad.HighByte
@ INT_RETURN

[Kenjones1935]

I do not understand this result. The gist is that the pulse generating command seems to influence
the interrupt frequency. Here is exactly our same code with a PULSOUT PORTD.7, 50 inside the
interrupt routine.

OSCCON = %01100000 '4 Mhz
DEFINE OSC 4

LED1    VAR PORTD.4
wsave VAR BYTE $70 SYSTEM
INCLUDE "DT_INTS-14.bas"     ' Base Interrupt System
INCLUDE "ReEnterPBP.bas"     ' Include if using PBP interrupts

ASM
INT_LIST  macro    ; IntSource,        Label,  Type, ResetFlag?
        INT_Handler   TMR1_INT,  _ToggleLED1,   PBP,  yes
    endm
    INT_CREATE               ; Creates the interrupt processor
ENDASM
'5.0 mSec OR 200 Hz INTERRUPTS
T1CON = %00000001         'Prescaler = 1:1, TMR1ON
'PRELOAD 60543
PreLoad     VAR WORD
PreLoad =  60543
TMR1L = PreLoad.LowByte
TMR1H = PreLoad.HighByte
@ INT_ENABLE  TMR1_INT     ; enable Timer 1 interrupts

Main:      'DO WHATEVER YOU WANT HERE
'  PAUSE 1000
'  HIGH PORTD.7
'  PAUSE 1000
'  LOW PORTD.7
GOTO Main

'---[TMR1 - interrupt handler]--------------------------------------------------
ToggleLED1:
     TOGGLE LED1
     pulsout PORTD.7,50
'     PWM PORTD.7,127,1
'     TOGGLE PORTC.6    'CONNECTED TO METER
     TMR1L = PreLoad.LowByte   ' Load the timer with preload value.
     TMR1H = PreLoad.HighByte
@ INT_RETURN

And here's the LOGIC TOOL picture.

[mackrackit]

Looks like the PULSOUT is taking longer than the interrupt. And of course I do not have the interrupt timed correctly.
Hopefully someone will straighten me out on the math.

[cncmachineguy]

According to the manual, each "PWM cycle" takes about 5ms with a 4Mhz clock. My guess is the first example has the interupt routine taking longer than the time between interupts. And you are prolly getting lucky to ever leave the handler at all!

The second example using pulseout, looks much better. Hard to count the lines, is it the correct timing?

Now remember, you don't want the pulseout in the interupt handler.

[Kenjones1935]

The correct picture is this one. PULSOUT is in the interrupt handler only after the RESET TIMER action. Why is this bad?

[cncmachineguy]

The general rule is to get in and out of an interupt as fast as possible. But in your case, the problem is a bit different. the pulse for the servo's should be every 20 msec. you have an interupt every 5 msec. so you are updating the servo 4 times as fast as you want to.

[ScaleRobotics]

Great job Ken. What you are doing is the best way to learn about the interrupts. You have to play with them. That is a great start.

I believe both pulsin and pulsout are blocking commands. While they run, nothing else can happen on your chip. Once they are finished, sure, things resume and the program takes over. For a single servo, this is fine. But once you start throwing in sonar, multiple servos, other things you have thought of, and some you haven't thought of yet ... then you start to run out of time to do all these things using blocking commands. Especially if you want to go 20 mph.

As it stands, 20mph is half a foot for each 20ms (that is every chance you get to make an R/C correction). For your sonar, it takes a bit over 20ms, so if that is the only input, the best your chip can do is determine a correction every other 20 ms, or every foot.

In fact, just listening to the echo pulse on your sonar takes up to 25 ms, so that alone screws up everything if we use blocking commands like pulsin. (and double the screwed if you are listening to two of these!)

So, in the long run I think it is best to use interrupts for listening to your sonars, as well as outputting to your servo's. I can't remember how you are switching your transmitter for R/C control vs pic control, but that too might as well go on interrupts.

If you do, you have all kinds of time. You can be listening for two sonars at the same time, chewing on some math to determine the amount of turn, etc. If you want speed, it is most definitely the way to go.

That said, exactly what you are currently doing to learn is what I would recommend. Use the commands you know with interrupts to make things happen, and see how they work, and how to adjust them. Later on, when you feel comfortable with them, try adding in another interrupt timer to control a servo pulse.

[cncmachineguy]

Hi Walter, I love what you are saying about using int instead of pulsein/out. I am having trouble visualizing how to do that.

In my head, something has to be the overall clock, thats where my suggestion of 5msec came from. when I think about what you are saying, all I seem to be able to see is all these events started waiting for an int to make them stop. so I see like 6 different timers going all at once.

Or maybe you have 1 timer going for the 20ms, then do everything else sequencially using a different timer.

EDIT: The slow sonars are gonna definitly limit the top speed! Maybe as an upgrade once it works slowly, infra red emitters and detectors. This way they could also be used at the same time by sending different signals on each.

[ScaleRobotics]

That's a great question Bert. Well, you being an asm guy will probably get a few laughs at my first real attempt at using more than 20 lines of asm in my program. But I will show you anyway. This uses Timer1 for PWM measurement (read servo channels in). Basically, Timer1 runs non-stop, and when a state change interrupt is detected, the timer value is read. The start timer value is subtracted from the stop timer value to get the pulse width. This is done for all channels. After all channels are read, it is time to output pulses to the servos. So I do not have a 20 ms timer, it cheats and uses the R/C receiver as the 20ms timer. If all channels have been read, it must be 20 ms. The second interrupt is timer0. That is used for pulse duration on the output. I made the pulse base 1ms, then the timer gets set for a second interrupt to complete the pulse.

Here is an example of reading 5 R/C channels, and outputting 4 R/C channels using two timers: http://www.scalerobotics.com/PWMpassthrough.html

Something like that could be used. And in addition to detecting servo pulse in, and interrupt on change could time a pulse from two sonars at the same time. This could also read timer1 start and end times, so no additional timers would be needed. If you did not want to use the R/C receiver as the 20 ms timer, then timer2 could be used. But that is the last timer on this chip. But then, you can still throw more on those two other timers, if you wish.

[cncmachineguy]

Walter I never find things to laugh about in code that works! Besides, 20 lines of asm isn't really much. Thats one of the reasons I wanted to convert to a high level language. Fewer lines to type

Ken is worried about firing both sonars at the same time cuz he may not know who the source is when it comes back.

[ScaleRobotics]

Ken is worried about firing both sonars at the same time cuz he may not know who the source is when it comes back.

Ken was thinking smarter than I. Good point. Maybe keep your sonar for front view, and for side view something like this: http://www.acroname.com/robotics/parts/gp2y0a21yk_e.pdf . Or use infra sensors for both, since you can get updates every 20 ms to keep up with the fastest that you can change your servos. Besides, they are cheaper than sonar! You do need to pick your distance range though. The one I gave a link to was 4 inches to 30 inches, which seemed ok for following a wall. If its 30 inches or more, get closer....

[Kenjones1935]

Yes, "blocking commands" is exactly the word. I figured that out while lying in bed with the LOGIC TOOL image in my head. I could see that the length of the pulse was being added to the interrupt time. I could not find any information on that in any of my documents. Please tell me where in which .INC file is the ASM code which is activated by PULSOUT. Without access to those details, PBP is just guess work.

My plan is to insert counters into the interrupt service routine. Every four interrupts (20millisec) do a PULSOUT. Every 25 interrupts, TRIGGER one SONAR or the other alternatively. My TRIGGER is built of HIGH and LOW commands totaling 10 microseconds (or so). These are not blocking.

I'll give this a try and see how the car reacts (if at all.....)

Thanks again for the support.

Ken

[ScaleRobotics]

Please tell me where in which .INC file is the ASM code which is activated by PULSOUT. Without access to those details, PBP is just guess work.

I would approach it a different way, and avoid that pain. Especially since interrupts may grow on you, and you may get rid of your pulsin/out someday ! Say you want an interrupt every 20 ms and have a single servo to control, but you want to use pulsout since you are still learning interrupts. Since we can be a little off on our 20 ms, as Bert mentioned, the easy way is to say the average servo pulse is 1.5ms, so I need to interrupt every 18.5 seconds. If you add in the time of your pulsout, it will be very close to 20 ms, and your servo will be happy and grateful.

[ScaleRobotics]

My plan is to insert counters into the interrupt service routine. Every four interrupts (20millisec) do a PULSOUT. Every 25 interrupts, TRIGGER one SONAR or the other alternatively. My TRIGGER is built of HIGH and LOW commands totaling 10 microseconds (or so). These are not blocking.

If that plan is just for testing, it sounds like a great plan. But if you plan to use it while doing 20 mph, you will be doing a "ping" every 3.66 feet, or 8 times per second. If your reflexes are quick, you might be able to blink your eyes quickly at about 8 times per second. While your R/C car is doing 20 mph around a turn, try blinking your eyes as fast as you can, while steering your R/C car. I think your results might be similar to the ones we saw in the video.

[cncmachineguy]

see, this is one of the reasons I love this stuff. To do what Walter describes, with the same resources (1 interupt and pulsout), I would set my timer for 20 ms. My int handler would set a flag, and I would get out. Then in my Main, if the flag is set, hit my pulseout routine and clear the flag. This way I would get a new pulse every 20 ms on the dot. But mostly cuz I just always want to get out of the handler. I seem to feel like by name "Interupt" I was busy doing something before I went there. Maybe it was important and I need to get back to it.

As for PBP being guess work, I don't think thats the case. Pulseout/in serout/in and the rest of them, take exactly as long as you think. if you PULSEOUT for 1 ms, thats how long it will take.

[cncmachineguy]

Walter, I like your idea of the 18.5 ms plus servo out to make up the 20ms loop. I need just that for my project. I will want to use 1 timer to control the loop and the pulse, so that seems the best idea to me.

[Kenjones1935]

"Verification of Program Memory failed at address 0x00000000"

I tried some old code that I KNOW loaded. Not today.

I swapped out the PIC. That was not the problem. I reseated all the patch wires. That made no difference.

I restarted the PICKIT2 programmer. That did not help.

I tried with a PICKIT2 board - the one on which I ran the blinkys - no problem. It liked to load and blink.

Where do I start?

Ken

[Kenjones1935]

It was a wire I had added to give the LOGIC TOOL more information. I do not understand why the PICKIT objected. But all is well.

The interrupt driven system sort of works. We'll see more tomorrow.

Thanks again for your help and support.

Ken

[Kenjones1935]

I've got the system working interrupt driven. I do not have proportional controls implemented - yet.

On the bench the car seems as responsive as before. We'll see when I take it to the gym.

One thing I have not figured. How, now, to I disable interrupts when the radio transmitter has been
turned ON? At the very end of this code pack is my old WHILE loop that worked - in the day.

symbol trigright = PORTB.0 ' Define output pin for Trigger pulse
symbol trigfront = PORTB.1 ' Define output pin for Trigger pulse
symbol trigleft  = PORTB.3 ' Define output pin for TRigger pulse
symbol echoright = PORTC.6 ' Define input pin for Echo pulse
symbol echofront = PORTC.5 ' Define input pin for Echo pulse
symbol echoleft  = PORTC.7 ' Define input pin for Echo pulse
SYMBOL channel3  = PORTC.4 ' Define input pin for Channel 3 PWM
' PORTC.0 'High is R/C.  Low is PIC control
TRISC = %11110000
DATA $C0,$0C 'his version's checksum goes here.
define ADC_BITS 8
TRISA.0 = 1 'PORTA.0 as analog input for POT
ANSEL.0 = 1
ADCON1 = %00000000  'left justified 
' We use low eight bits.  0 -> 255.
ADCON0 = %01000001  'divide 4Mhz clock by 8.

'------------
OSCCON = %01100000 '4 Mhz
DEFINE OSC 4

LED1    VAR PORTD.4
wsave VAR BYTE $70 SYSTEM
INCLUDE "DT_INTS-14.bas"     ' Base Interrupt System
INCLUDE "ReEnterPBP.bas"     ' Include if using PBP interrupts

ASM
INT_LIST  macro    ; IntSource,        Label,  Type, ResetFlag?
        INT_Handler   TMR1_INT,  _ToggleLED1,   PBP,  yes
    endm
    INT_CREATE               ; Creates the interrupt processor
ENDASM
      
'------------

'5.0 mSec OR 200 Hz INTERRUPTS
T1CON = %00000001         'Prescaler = 1:1, TMR1ON
'PRELOAD 60543
PreLoad     VAR WORD
PreLoad =  60543
TMR1L = PreLoad.LowByte
TMR1H = PreLoad.HighByte
'@ INT_ENABLE  TMR1_INT     ; enable Timer 1 interrupts

'------------
WHEELS VAR WORD
STEERING VAR WORD

'The following may be a big part of the wall hugging probllem
Potread var word
Forward var word ' was fixed 122. Now sweeps 7 steps. See Checkpot
HalfForward VAR WORD ' Potread/2 +x + 1. See Checkpot
Back VAR WORD 'See Checkpot
HalfBack VAR WORD 'See Checkpot
Brake con 100 'Only used just before Main.

Straight con 150 '?
Right CON 130     '?
HalfRight con 135 '?
QuarterRight CON 140 '?
Left con 170     '?
HalfLeft con 165 '?
QuarterLeft con 160 '?

'---------------------------
frontdanger var word
stopreversing var word
frontfree var word
desiredtrack var word
outertrack var word 

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

'some of the following are not used.
CNT  VAR BYTE 'counts interrupts for TRIGGERS
cnt = 0
CNT2  var byte ' counts interrups for wheels and steering
CNT2 = 0
b0 VAR word
rangeright var word
rangeright = 100  'about 6 inches preset
rangefront var word
oldrangeright var word
oldrangefront var word
reversing VAR WORD
reversing = 0
switchtoPIC VAR WORD
switchtoPIC = 1
radiocontrol var word
radiocontrol = 0
steeringleft var word
steeringleft = 0
steeringright var word
steeringright = 0

'-------------------
Checkpot:
' I think Potread goes from 0 to 6.
adcin PORTA.0, Potread
Potread = Potread/37
Forward = 160+Potread
HalfForward = 155+(Potread/2)  'seems to work.
Back = 140-Potread
HalfBack = 145-(Potread/2)
'----------
frontdanger = 210 + Potread*55 '210-540, 14-36 inches 
stopreversing = 180 + Potread*25 '180-330, 12-22 inches
frontfree = 700 + Potread*60 '700-1060, 48-70 inches
desiredtrack = 180 + Potread*20 '180-300, 12-20 inches 
outertrack = 360 + Potread*15 '360-450, 24-30 inches

'----------
write 2, word Potread
write 4, word frontdanger
write 6, word stopreversing
write 8, word frontfree
write 10, WORD desiredtrack
write 12, word outertrack

'-------------------
@ INT_ENABLE  TMR1_INT     ; enable Timer 1 interrupts

'-------------------
low PORTC.0
'hpwm 1,Straight,50
STEERING = Straight
'hpwm 2,Brake,50
WHEELS = Brake
'pause 4000 'Wait so I can put the car down and get out of the way.
'-------------------

main:

CheckIfInDanger:
if rangefront < frontdanger then
STEERING = Straight
WHEELS = back
reversing = 1
goto reverseoutoftrouble
' loop till this is secured
endif 
'-------------------
tryleftturn:
if rangefront < frontfree then
'something ahead - turn hard left.
STEERING = left
WHEELS = halfforward
  steeringleft = 1
 goto main 'loop till this is secured
endif

'------------------- 
goingforward:                          
STEERING = straight
WHEELS = forward

'-------------------
keepgoingforward: '----Compare to right wall
if rangeright > outertrack then
  STEERING = quarterright
endif

if rangeright < desiredtrack and oldrangeright < rangeright then
  STEERING = STRAIGHT
endif 
  
if rangeright > desiredtrack and oldrangeright > rangeright then
  STEERING = STRAIGHT
endif

if rangeright > desiredtrack and oldrangeright < rangeright then
  STEERING = QUARTERRIGHT
endif

if rangeright < desiredtrack and oldrangeright >= rangeright then
  STEERING = QUARTERLEFT
endif

goto main

'-------------------------
reverseoutoftrouble:
while rangefront < stopreversing
  STEERING = RIGHT
  WHEELS = RIGHT
wend 

if rangeright > outertrack or rangeright < desiredtrack then 
  STEERING = LEFT
  steeringleft = 1
  WHEELS = HALFFORWARD
endif
goto main

'***********INTERRUPT HANDLER************
ToggleLED1: 
TMR1L = PreLoad.LowByte   ' Load the timer with preload value.
TMR1H = PreLoad.HighByte
TOGGLE LED1

'------------
' Trigger SONAR alternatively every 25 interrupts
if CNT=25 then
 pulsr:
 oldrangeright = rangeright
' produce 10uS trigger pulse (must be minimum of 10uS)
 low trigright
 HIGH trigright
 high trigright
 high trigright
 LOW trigright
'zero could be legal below
 pulsin echoright,1,rangeright 'measures the range in 10uS steps
 endif

'-------------
if CNT=50 then
 pulsf: 
 oldrangefront = rangefront 
 low trigfront
 hIGH trigfront
 high trigfront
 high trigfront
 LOW trigfront
 pulsin echofront,1,rangefront ' measures the range in 10uS steps
 CNT=0
endif
 CNT=CNT+1

'--------------
if cnt2=4  then
' PWM pulses are between 1 and 2 millisec.
    low PORTC.1
    low PORTC.2
    pulsout PORTC.1,WHEELS  
    PULSOUT PORTC.2,STEERING   
    CNT2=0
endif
CNT2=CNT2+1
    
@ INT_RETURN
checkchannel3:
'works with four AA batteries pack. Radio receiver puts pulses
'on this line whenever the transmitter is turned ON.
 switchtoPIC = 2
 while switchtoPIC >= 2
    count channel3,65,switchtoPIC
    high portc.0
 wend
   low portc.0   
      
end

[cncmachineguy]

@ INT_ENABLE  TMR1_INT     ; enable Timer 1 interrupts

that line turns the interupt on, or enables it. there must be a simular line like INT_DISABLE maybe to turn it off.
turn it off when the while loop is true, or when under Tx control. then turn it back on when Tx control is over.

[Kenjones1935]

For some reason disabling interrupt during the WHILE loop did not work. I could have done
something stupid.

What I want to know is where is the list of "blocking" commands. I do not see such a list in
my PBP book. For example, is COUNT a blocker?

Here is what I coded immediately after main:
main:

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

checkchannel3:
'worked with four AA batteries pack. Radio receiver puts pulses
'on this line whenever the transmitter is turned ON.
switchtoPIC = 2
while switchtoPIC >= 2
@ INT_DISABLE TMR1_INT
count channel3,65,switchtoPIC
high portc.0
wend
low portc.0
@ INT_ENABLE TMR1_INT

Ken

[ScaleRobotics]

Ken, can you give us a bigger snippet?

[Kenjones1935]

I took my interrupt driven car to the gym this morning. It behaved about the same as my old HPWM design. When going slowly it just barely made the left turns at the corners. It did seem to go straight with less wiggle, but it still hit the wall occasionally.

It appears that the problem is reaction time. My delving into an interrupt driven system was motivated by the guess that randomly (in time) changing the HPWM command might be confusing the electronic speed control. On this account I detect little difference.

Another reason for regularly timed SONAR triggers was to take advantage of PID control. I have not coded that experiment. I am not convinced quicker reaction time will result.

I partially solved the TOGGLE problem by inserting the following code right after 'main:'. This system does not toggle control between PIC and RC, but it does stop (Brake) the car when the radio transmitter is turned ON. It is not a nice picture - a 75 year old man running around a gymnasium trying to tackle an out-of-control RC car.

The code samples channel3. This is the steering PWM signal from the car's radio receiver. There are pulses on that line as soon as the transmitter is activated.

main:
switchtoPIC = 2
WHILE switchtoPIC >= 2
COUNT channel3, 65, switchtoPIC
WHEELS = Brake
WEND

I am not sure what to do now. The reaction time seems quick enough on the bench.

[Kenjones1935]

In order to make sense of interrupt driven controls I need to know which PBP commands are 'blocking'. Why? During the blocking time no PWM pulses and no SONAR triggers are being emitted.

Ken

[Kenjones1935]

Back a couple weeks one of you mentioned using infrared distance detector instead of a sonar detector. How do I find that posting? What was he product's name? How does it work? Or am I mistaken.

Ken

[ScaleRobotics]

Ken, the one I suggested earlier http://www.acroname.com/robotics/parts/gp2y0a21yk_e.pdf... well, I just read the timing chart on page 4, and believe it or not, this infra red sensor is slower than your sonar! But, the good part is, you wouldn't have to wait for one to finish, before sensing the other. It would be nice to find a faster response sensor, if possible though, to allow your car to measure under 20 ms (at least for the side).

Here's a little bit about how they work http://www.societyofrobots.com/robot...p?topic=7991.0

[ScaleRobotics]

In order to make sense of interrupt driven controls I need to know which PBP commands are 'blocking'. Why? During the blocking time no PWM pulses and no SONAR triggers are being emitted.

Interrupts are the way around blocking commands. With interrupts, you can be listening for 4 separate pulses in, while pulsing 4 separate pulses out, while listening for the sonar ping, and blinking a few led's, etc, etc. With PicBasic commands alone, you are still stuck at pulsin, listening for a single pin for x duration. Don't get me wrong, blocking sounds so bad, but what it really does, is give the user a simple way do some complex things, with a single line of code. And without having to read about 50 extra pages of the data sheet. This is one of the best features of PicBasic. But there is a time for interrupts. Pulsin, Pulsout, PWM, serin, serout, freqout, count, debug, debugout are a few blocking commands.

That said, they will not block an interrupt. An interrupt, does what it does best. It butts in an interrupts, gets out, and then whatever PicBasic command it was in the middle of completes.

[Ioannis]

Up to this moment I have not seen any specifications of the cars.

What speed they reach, how fast thay accelerate and how fast do they stop.

If youhave this figures then you may do the calculations about reaction time and maximum speed to reach in order to hit the brakes in time, before crashing on the walls.

Ioannis

[ScaleRobotics]

Looking back at one of the examples you gave of this idea (from kind of the beginning), Wall Racers used no interrupts. It was all done using basic statements, and blocking commands. These cars seem to go a bit slower than yours though, if I were to guestimate. Is the accuracy and speed they have in this video what you are aiming for? I think I saw them hit a wall here and there ... maybe. I am guessing around 4 to 5mph in the video?



Here is the code they used in PicAxe Basic.

' WALLRACERS By Frits Lyneborg
' Right turns on the track must be gentle (this code does not skid/slide on them), left can be hard (skid/slide is build in)

' <"left"> opposite just <left> in the remarks means that wheels are turning left, but direction is backwards, so "left" is actually moving right

symbol trigright = 0 ‘ Define output pin for Trigger pulse
symbol trigfront = 1 ‘ Define output pin for Trigger pulse

symbol echoright = 7 ‘ Define input pin for Echo pulse
symbol echofront = 6 ‘ Define input pin for Echo pulse
symbol rangeright = w1 ‘ 16 bit word variable for range
symbol rangefront = w2 ‘ 16 bit word variable for range
symbol oldrangeright = w3 ‘ 16 bit word variable for range
symbol differencerangeright = w4 ‘ used to calculate how hard a turn is
symbol frontfreetostopreverse = w5

symbol turnon = 7 ' the relay that if on makes the car turn to one side
symbol steerto = 6 ' the relay that if on turning is on, then decides the direction
symbol stopon = 5 ' the relay that if on makes the car stop
symbol forrev = 4 ' the relay that if on and is not on stop makes the car reverse


symbol frontdanger = 200 ' At what point should we realize we are getting too close? (note that breaking takes a lot, so this should be much higher than the real distance)
symbol frontfreetostopreversesetup = 201' must be higher than "frontdanger" - higher value means more backing out after close encounters
symbol frontfree = 350' set higher to turn earlier when something is in front, and get less skid-turning, but more likeliness to miss sharp right turns

symbol desiredtrack = 100
'symbol innertrack = 50
symbol outertrack = 150

high stopon
wait 5
low stopon 

'''''''''''

main:
oldrangeright = rangeright
gosub puls
gosub skidandreverse
if rangefront < frontfree then 'turn left as there is something ahead in front
high turnon low steerto 
goto main 'this is second priority above all loop till this is secured
end if


'' Normal drive to the right - we are too far away from the lane, so turn. This code contains no right-slide-turn for cool long right turns without slides to give more of a race-feeling oposed to zig-zag and robot-behaviour, so space must on thr track be higher than turning-radius in front of right turns - or the car vill turn left and miss the right turn.
if rangeright > outertrack then 'turn right as we are too far away
high turnon  high steerto 
end if



' Now we know that there is nothing closer than (frontdanger and) frontfree - and we are on track - so let's keep on track

'***
' First check if we are on the right path and have a positive development. 
' If so, then keep us there by straightening up wheels that might be turned

if rangeright < desiredtrack and oldrangeright < rangeright then
low turnon  low steerto  ' drive straight forward as we are on the wrong side of desired track, but we are moving the right direction
end if

if rangeright > desiredtrack and oldrangeright > rangeright then
low turnon  low steerto  ' drive straight forward as we are on the wrong side of desired track, but we are moving the right direction 
end if

'***
' Then see if we are moving away from the good path and do something about it if so.

if rangeright > desiredtrack and oldrangeright < rangeright then
high turnon  high steerto  'turn right as we are in the outer lane and getting away
end if

if rangeright < desiredtrack and oldrangeright > rangeright then
high turnon  low steerto  'turn left as we are in the inner lane and getting closer
end if

goto main

'***************************************

yankright:' there was an empty space to the right. Skid right to be sure we are turning if it is a turn in the track


'''''''''' Skidsecure start
high turnon  high steerto  'turn right
pause 25' wait short for the car to give a small yank to the left before reversing.. all to start a skid turn to the right side
'''''''''' Skidsecure end

high forrev  'set in reverse gear


Skidright:
b0 = 0

do
gosub puls
b0 = b0 +1
loop while rangefront > frontfreetostopreverse and rangeright > outertrack and b0 < 20

'dildo:
'high stopon goto dildo

low forrev  'set in forward gear
pause 300

return


'***************************************



'***************************************

reverseoutoftrouble:

'''''''''' Skidsecure start
high turnon  low steerto  'turn left
pause 25' wait short for the car to give a small yank to the left before reversing.. all to start a skid turn to the right side
'''''''''' Skidsecure end

high forrev  'set in reverse gear

rev:
frontfreetostopreverse = frontfreetostopreversesetup

keepreversing:
frontfreetostopreverse = frontfreetostopreverse - 3' making sure we are not backing and reversing and going nowhere, as we have a wall behind us

if frontfreetostopreverse < 50 then
gosub stuckerror
end if

gosub puls
if rangefront < frontfreetostopreversesetup then

    if rangeright < desiredtrack and oldrangeright < rangeright and rangefront > frontdanger then
    low turnon  low steerto  ' drive ahead as we are on the wrong side, but we are moving the right direction and we are not too close
    end if

    if rangeright > desiredtrack and oldrangeright > rangeright and rangefront > frontdanger then
    low turnon  low steerto  ' drive ahead as we are on the wrong side, but we are moving the right direction and we are not too close
    end if


    if rangeright > desiredtrack and oldrangeright < rangeright and rangefront > frontdanger then
    high turnon  low steerto  'turn left (reversed) as we are in the inner lane and getting closer
    end if

    if rangeright < desiredtrack and oldrangeright > rangeright then
    high turnon  high steerto  'turn right (reversed) as we are in the outer lane and getting away
    end if

    goto keepreversing
end if

high turnon low steerto  'turn "left"
low forrev  'set in forward gear

return


'*************

skidandreverse:
if rangefront < frontdanger then ' too close, reverse out of trouble!
gosub reverseoutoftrouble
goto main ' this is first priority above all - loop till this is secured
end if
return

'*************

puls:
pulsout trigright,2 ‘ produce 20uS trigger pulse (must be minimum of 10uS)
pulsin echoright,1,rangeright ‘ measures the range in 10uS steps
pulsf:
pulsout trigfront,2 ‘ produce 20uS trigger pulse (must be minimum of 10uS)
pulsin echofront,1,rangefront ‘ measures the range in 10uS steps
pause 10 ‘ recharge period after ranging completes
return


stuckerror:
high stopon
low forrev
low steerto
low turnon
dadaa:
goto dadaa

[Kenjones1935]

You are right about the specs on the RC cars. I do not know that they officially exist. My car weights exactly four pounds. Has good rubber tires with plenty of friction against the gymnasium floor. I have been told that it is good for at least twenty miles per hour, but I have no means to verify it. The car is a HPI-Racing 1/10 Scale, 4 wheel drive, Sprint model.

Regarding the blocking commands. All I want to know is which ones block TMR1 and hence TMR1 based interrupts? Judging from my LOGIC TOOL images PULSIN blocks. True?

Ken

[ScaleRobotics]

Regarding the blocking commands. All I want to know is which ones block TMR1 and hence TMR1 based interrupts? Judging from my LOGIC TOOL images PULSIN blocks. True?

I thought I read somewhere that most of the commands which involve time, like Pulsin, Pulsout, etc, use timer1. But I can't find anything documenting that. Maybe someone can correct this for me? I did a little testing, and if you put your 20 ms timer on Timer2, it will be unaffected by pulsout, and I expect pulsin as well. These blocking commands DO NOT block an interrupt. For instance, you can have a pause 10000 in your main, while an interrupt gives you a heartbeat LED indication every second. But they will interfere if they are trying to load the same timer with a value.

EDIT: Turns out I was way off base here. Here Darrel corrects me:

The only PicBasic command that uses a timer is HPWM, which uses Timer2.
No PBP commands use Timer1 unless you tell it to.

And all PBP commands are blocking (while they execute).
They might interface with harware peripherals that are doing other things at the same time, but the statements themselves are blocking.

As you pointed out though, they don't block interrupts.
And it's the commands that do software based timing that get disturbed by the interrupts.
PAUSE, PULSIN/OUT, RCTIME, SEROUT/IN(2) etc.
They stop keeping time while the interrupt code executes, so all that time gets lost.

When using interrupts, you should use Hardware Timers to do things like PAUSE or PULSIN, and the USART instead if SEROUT/IN(2).
And when not using interrupts, use the easier versions (PBP), or still use the hardware which are the NON-BLOCKED functions.

You can do PULSIN with the CCP module at the same time you're sending serial data to a PC without any interrupts.

[Kenjones1935]

You are correct. I got the whole idea from Frits. I have learned some since then.

1. His cars were 1/12 scale toy level cars. They are not fast by RC standards. They have only bang bang steering and wheel control. They are small. They do not have enough room for much electronics to be added. Frits removed the RC receiver. I tried the Frits thing on a 1/10. I was not successful. The 1/10 car is much faster than the 1/12 car. This video shows the difference.



I have been asking for suggestions for a 'game' that can be played with the 1/10 Toy level cars. They are $50 each vs $200 for a model level car.
I thought up the 'swarm the teacher with the light bulb' game to be played with multiple light sensing diodes on the roofs of the cars. I have been diverted by this idea of interrupt driven model level control.

Thanks for everything.

KEn

[cncmachineguy]

Ken, Sorry, I'm not very good at thinking up games. Follow the light sounds like fun to me. I have a lot of things I want to comment about your current effort, but time won't let me right now. I will tonight. Let me say this though, I think you are on the right path.

I wonder if you can do some testing for us. I want to help you get better control over the car, but need some parameters.

1. How close can you get to a wall at top speed and still be able to execute a turn?
2. How close do you want to be to the right wall?
3. At what percentage of speed can you still make a hard left without the car skiding?
4. If the Tx is NOT on, will there be any pulse from the RX?

Maybe you can put some tape lines on the floor and film that section of the floor to capture speed and distance from the wall. Of course this will be under manual control, So we will also get to see your reflexes-lol

I for 1 believe you can get the car to go much faster and be WAY more accurate!!

[Kenjones1935]

My gymnasium has no electricity. Need bright sunny day to take video. Tomorrow is Thanksgiving and the following day is occupied by family stuff.

The model car does not skid. The toy car does.

In my older model level car, the receiver created no pulses on channel3 input when the transmitter was off. My newer model level car, somehow has noise on that line. The circuits are the same. I have not been able to figure out the difference.

I started trying to code my 1/10 toy car to do a skid turn then I realized that it's real problem is the subtle issue of staying parallel to the wall. I think you have a real good idea asking me to see whether I can control that car with its RC inside my gym.

Thanks for the encouragement. I have been bumping my head for a while.

Ken