PBP projects for R/C models

[Kenjones1935]

Mucho frustrations followed by some successes. The PC board proto challenge is beyond me for now. Created instead a car that toggles itself between radio and PIC control without using a third radio channel and negotiates a maze that includes both right and left turns.

The auto toggle is a function of the car being out in the clear - not in or too near the cardboard maze. The right and left turns were pretty obvious after numerous stupidities.

I hope to post a video next week.

Thanks again for all your support.

Ken

[Kenjones1935]

I think the code is pretty solid. Now the problem is response time, size of maze passageways and RC car speed. A fraction of a second does not seem very long when the car is up on blocks, but it is enough time at speed to crash into a far wall when it should have detected a turning opportunity and done its thing.

I think I need:
1. Techniques using PICBASIC Pro for recording data in memory that can be read back into my PC for analysis. How do I do this? I have not the faintest idea what app to use.

[mackrackit]

This is a tough one.

If the trouble is speed and timing then using more MCU cycles might make it worse.

You can look at writing data to the on-board EEPROM.
http://melabs.com/resources/samples/pbp/eeword.htm

[ardhuru]

I think I need:
1. Techniques using PICBASIC Pro for recording data in memory that can be read back into my PC for analysis. How do I do this? I have not the faintest idea what app to use.

This thread might help:

http://www.picbasic.co.uk/forum/arch...p/t-13317.html

Regards,

Anand

[Kenjones1935]

Thanks for your attention and replies.

I think the PIC is plenty fast enough. I think the SFR05's are responding quickly enough judging from their flashing LED's. My guesses are either SFR inconsistencies and/or weakness in my jury rigged PWM signal.

The servo and the speed control want PWM pulses at 50 per second. I have not been able to do that with my PIC. I get the pulse width correct, but I can not get the rep rate down to once each 20 millisec.

Ken

[Kenjones1935]

The PIC KIT2 programmer has, at the bottom, reference to EEPROM. It has addresses 00 - FF.

I think that if I use the PBP WRITE command at run time I can store data in the inchip EEPROM space. 00 to FF in size. I can then manually read this out with PIC KIT2 programmer.

Sound correct??

Ken

[mackrackit]

Sound correct??

Yup, that will work.

[Kenjones1935]

I need to be able to connect my PICkit 2 to three SRF05 sonar sensors. The easiest way would be to solder J or JR (or whatever - I do not know one connector from another) headers to the board.

I looked carefully at the connectors that came with my radio control car. The pin separation does not match the hole separations in my PICkit 2 forty four pin demo board. Do any of you know the name of the connector header - if it exists - that would solder directly into that row of holes along the sides of my proto card? They are definitely not 1/10 inch centers. I have no means to measure their separation accurately.

Ken

[ScaleRobotics]

The 18F2431 makes it slightly easier to perform servo PWM because it's PCPWM module can go down to 19 htz while maintaining fast OSC rates, unlike other PIC chips HPWM. Here is an example of using the PCPWM to output 3 servo signals. This specific example senses the pulses (up to 5 channels) by using the CCP1 capture pin. To get 5 channels into one pin for PW capture, channels 1, 3 and 5 are input using small signal diodes. Then, since this drops the signal down to under 3 volts, I used two 2n3904 transistors. One to boost up the voltage, and the other one to invert the signal back to normal. (It was all I had lying around). Somehow, you will need to boost your signal after the diodes for the CCP1 capture to sense the incoming pulses.

Note: Because the PCPWM was used, this will not work on any chip outside of the 18F2431 family.

;This only works on a 18F2431 family device with Power Control PWM (PCPWM)
;By Scale Robotics Inc. 
; The input signal should look something like this:- 
;
;        |<------------------ 1 frame (~20mS) -------------->|
;        |<1~2mS>                                 
;         ______        ______        ______                  ______
; _______|      |______|      |______|      |________________|      |____
;   gap    ch1    ch2    ch3    ch4    ch5      sync  gap      ch1    etc
define OSC 40
asm
    __CONFIG    _CONFIG1H, _OSC_HSPLL_1H
    __CONFIG    _CONFIG2H, _WDTEN_OFF_2H & _WDPS_512_2H
    __CONFIG    _CONFIG4L, _LVP_OFF_4L
endasm
clear 
ADCON0 = %00000000
ADCON1 = %00000000
portb=0
trisb = %11000000
trisc = %00000110
trisa = %00000000
DTCON = %00000101   'dead time for complimentary ouputs
PTCON0 = %00001101  '1:1 postscale, Fosc/4 1:64 prescale, Sincle Shot mode
PTPERL = 255        ' 
PTPERH = 251
PWMCON0 =%01010000  'PWM[5:0] ouputs enabled
PWMCON1 = 1         'updates enabled, overrides sync w/timebase
PTCON1 = %10000000  'PWM timebase is on, counts up
FLTCONFIG = %00000010 'disable fault A, cycle by cycle mode
CCP1CON = %00000101    'Capture mode; every rising edge

duty1 var word        'width of outgoing pulse1
duty2 var word  'duty values 625 to 1250 = 1 to 2 ms pulse (Center at 625)
duty3 var word
risetime1 var word    'Rise Time for incoming pulse1 
risetime2 var word
risetime3 var word
falltime1 var word     'falltime for incoming pulse1
falltime2 var word
falltime3 var word
pulsewidth1 var word    'pulse width for incoming pulse1
pulsewidth2 var word
pulsewidth3 var word
pulsewidth4 var word     
pulsewidth5 var word
pulseNumber var byte
pulseNumber = 1         'tells which pulse we are reading
CCP1CON.0  = 1
timerone var word 
timerone = 60315 ;

INCLUDE "DT_INTS-18.bas"     ; Base Interrupt System 
ASM
 
INT_LIST  macro    ; IntSource,        Label,  Type, ResetFlag?
        INT_Handler   TMR5_INT,   _PulseOut,   ASM,  yes
        INT_Handler   CCP1_INT,   _PulseMeasure,   ASM,  yes
        INT_Handler   TMR0_INT,   _TimeOut, ASM, yes
    endm
    INT_CREATE               ; Creates the interrupt processor
ENDASM
 
T1CON = %00110001            ;Timer1 used by CCP1 capture
T5CON = $01                  ;used as pulseout timer
T0CON = %11000111              ; Prescaler = 8, TMR1ON

@   INT_ENABLE  TMR5_INT     ; Enable Timer 1 Interrupts            
@   INT_ENABLE  CCP1_INT      ; Enable Capture Compare for pulse width measurement
@   INT_ENABLE  TMR0_INT    ; deadtime (sync gap) indicator for lull between pulses
Main:
        pause 10
        'do something to these values if you want to filter, center, etc
        'Below we are just passing values through
        duty1 = pulsewidth1 >>1  'send channel 1 out PCPWM on PortB.1
        duty2 = pulsewidth3 >>1  'send channel 3 out PCPWM on PortB.3
        duty3 = pulsewidth5 >>1  'send channel 5 out PCPWM on PortB.4
GOTO Main
 
'---[TMR5_INT - interrupt handler]------------------------------------------ 
PulseOut: 'set up pulse width values for pulseout and reset single shot bit
    TMR5L = timerone.byte0
    TMR5H = timerone.byte1
    PDC0L = duty1.lowbyte
    PDC0H = duty1.highbyte
    PDC1L = duty2.lowbyte
    PDC1H = duty2.highbyte
    PDC2L = duty3.lowbyte
    PDC2H = duty3.highbyte
    PTCON1.7=1  'resets single shot PTEN bit
@    INT_RETURN
    
'---[CCP1_INT - interrupt handler]------------------------------------------
PulseMeasure:
if CCP1CON.0  = 1 then ; Check CCP1M0 for rising edge watch
    select case pulseNumber
        case 1
            TMR0L = 0    'reset timeout timer0
            TMR0H = 0
            risetime1.lowbyte = CCPR1L
            risetime1.highbyte = CCPR1H
        case 2
            TMR0L = 0    'reset timeout timer0
            TMR0H = 0
            risetime2.lowbyte = CCPR1L
            risetime2.highbyte = CCPR1H    
        case 3
            TMR0L = 0    'reset timeout timer0
            TMR0H = 0
            risetime3.lowbyte = CCPR1L
            risetime3.highbyte = CCPR1H
    End select 
    @ BCF     CCP1CON, CCP1M0 ; Now capture the trailing edge     
Else     'check for falling edge time
    @ BSF     CCP1CON, CCP1M0 ; Re-set for trailing edge capture
    select case pulsenumber
        case 1
            falltime1.lowbyte = CCPR1L
            falltime1.highbyte = CCPR1H
            pulsewidth1 = falltime1 - risetime1
        case 2
            falltime2.lowbyte = CCPR1L
            falltime2.highbyte = CCPR1H
            pulsewidth2 = risetime2 - falltime1
            pulsewidth3 = falltime2 - risetime2
        case 3
            falltime3.lowbyte = CCPR1L
            falltime3.highbyte = CCPR1H
            pulsewidth4 = risetime3 - falltime2
            pulsewidth5 = falltime3 - risetime3
    end select 
    pulsenumber = pulsenumber + 1 'get ready for next channel
        
endif
@    INT_RETURN
'---[TMR0_INT - interrupt handler]------------------------------------------
TimeOut:
    pulsenumber = 1 'if pause between pulse in exceeds about 7 ms, get ready
    'to receive pulse 1 (senses dead time between pulse bursts)
@   INT_RETURN

To see a similar project, but using SPWM, look here: http://www.picbasic.co.uk/forum/showthread.php?t=12657

[Kenjones1935]

Yes, the 18F2431 looks like a winner for my PWM construction. It is included in my PICkit2 programmer.
It comes in a 40 pin package. It would easily replace my 40 pin 16F887 on the solderless protoboard. To use it effectively I need to master ASM coding. I have not succeeded in cracking that nut.

Here is my latest stumbling block. I have an arrangement with some folks who are willing to contribute brand new HPI Racing Sprint cars to my project. I received my first new car last week. HPI has drastically changed the Electronic Speed Control. This is the package that translates incoming PWM signals (from the radio receiver or from my PIC) into outgoing DC current for the motor that drives the wheels. I am not doing well with the HPI WEB site getting technical information about this SC-15 WITH REVERSE SPORT CONTROL.

Ken

[ScaleRobotics]

After reading about some of Bruce's cool projects with the 18F2431 series chips, I have been playing around with them for a little while. One thing that caught my eye is that they can do Power Control PWM as low as 19 hertz (while running at 40 mhz). Something you have to bring other chips OSC down to 0.5 mhz to do. This, and a few more of it's features, make it pretty nifty for creating PWM servo output. I mocked up a quick test, and have been able to do about 10bit PWM 1 to 2ms pulses at the proper 50 hertz spacing on 3 pins with the 18F2431. The larger chips of this series can do 4 pin PCPWM. I will post a little code once I get it cleaned up a bit.

[Kenjones1935]

I received a brand new HPI Racing Sprint car. This is the same model which I have been using. It is just the most recent version.

I am having a problem with the new Electronic Speed Control a SC-15. It has some kind of mind of its own. My old code which told my old car where to go is not working with this new ESC.

Do any of you have the contacts to get me the specs on this "SC-15 ESC WITH REVERSE SPORT CONTROL".

Does is have a PIC? Is it programmable? What are its design algorithms?

Ken

[ScaleRobotics]

Since it doesn't have to be exact, you could simplify your code.

Instead of:

Checkpot:
adcin PORTA.0, Potread
write 4, word Potread
select case Potread
case Potread < 36
Forward = 112
case Potread => 36 and Potread < 73
Forward = 113
case Potread => 73 and Potread < 109 
Forward = 114
case Potread =>109 and Potread < 146 
Forward = 115
case Potread => 146 and Potread < 182 
Forward = 116
case Potread => 182 and Potread < 219
Forward = 117
case Potread => 219
Forward = 118
end select
write 2, word Forward

something like:
8 bit ADC:

Checkpot:
adcin PORTA.0, Potread
Potread = Potread/37
Forward = Potread+112

10 bit ADC:

Checkpot:
adcin PORTA.0, Potread
Forward = Potread/147 + 112

[Kenjones1935]

I chose your first suggestion:
Potread = Potread/37
Forward = Potread+112

It works beautifully. Tomorrow I shall make a video of my car on blocks in its "going forward" state with me making it go faster and slower by twisting the pot's knob. At least I intend to do that tomorrow.

THANK YOU!!!

[Kenjones1935]

Sorry for the delay. I have been discouraged. The new HPI Sprint R/C car has an ESC-15 that thinks for itself. The HPI manufacturing/sales organization refuses to give me the behavioral specs. This is a STEM educational project. Not a by guess and by golly exercise in inductive reasoning.

One solution is to make an ESC on my solderless proto board. (Complete with cooling fins?)

My PIC (like the R/C receiver) makes appropriate PWM digital signals. The car wheels want appropriate PWM bi-directional current pulses. Have any of you seen a design I could copy?

Ken

[ScaleRobotics]

Here is some more info about StickOS with some youtube videos by the guy the wrote it. Pretty cool stuff.

http://www.picbasic.co.uk/forum/show...9397#post89397