PBP projects for R/C models

[mackrackit]

Looks like the only difference is you are using the latest software, I am still using PBP2.50 and MPLAB v8.00.

So I am at a loss now.

[Kenjones1935]

Progress has been slow. It will be more fun when the SN7407's show up and I can make the car move.

Ken

[Kenjones1935]

It's been more than a week. They were supposed to have been shipped via USPS. The vendor is not answering its email. Does not look good.

Meanwhile I might as well get back to the REAL project. I have not decided on the least intrusive means to generate PWM. Using the toy level car all I have is bang/bang control. Full speed forward, full speed backward, stopped. Full turn left, Full turn right, straight ahead.

With PWM control I have CONTROL. Thing is, I do not know whether I really need this complication. Probably not. But I do need for the microprocessor to be doing things while the car is moving. PAUSE does not cut it.

Gotta put back on my thinking cap.

Ken

[ScaleRobotics]

Hey Ken,

Don't know if you saw it, but some progress was made on the 12F683. It is decoding 5 channels, and encoding 4 channels. You could modify the servo output as you like in the main section, using PBP. The DT interrupts are done in assembly. (No pauses) All you would need is a $2.00 12f683, a capacitor, 3 diodes, and a breadboard.

http://www.picbasic.co.uk/forum/showthread.php?t=12657

[Kenjones1935]

The wall racer code contains subroutines that do all the bang/bang controls by switching DC current through relay DPDT switches

The 16F887 has CCP1 and CCP2 each of which can be controlled by the HPWM Pic Basic Command. I could replace the six subroutines above with six that use HPWM. They would use these two outputs with three pulse widths each.

If I were to add a parameter to each GOSUB command thereby giving more nuance to the pulse width I could command in between wheel speed and steering angle.

Sounds like a piece of cake. What do you think?

Ken

[ScaleRobotics]

The 16F887 has CCP1 and CCP2 each of which can be controlled by the HPWM Pic Basic Command. I could replace the six subroutines above with six that use HPWM. They would use these two outputs with three pulse widths each.

Hey Ken, I don't think I understand where you are heading. If you are talking about generating pulses for the servo's using HPWM, the low side for HPWM is 1.2 khz. Too fast for servos.

[rmteo]

Using a single CCPx module in Compare mode, trigger special event (CCP2M<3:0> = 1011), you can do 8 servo outputs within a 20mS frame (50Hz) and 1uS resolution with a 4MHz clock.

[Kenjones1935]

My original project uses a hobby level RC car. It has an electronic speed control which directs the DC power into the wheels. This ESC expects a pulse width modulated signal from the RC receiver. Last month I wrote very simple code using HPWM commands running in my 16F887 that made the wheels go forward, backward, stop and controlled the steering . With a little playing I got various speeds and less than full stop steering.

I jumped over to the wall-racer to get a feel for coding in BASIC on my PICkit 2. I stopped because the power requirements of the relay driven DPDT current switches exceed the capabilities of the microprocessor. I ordered some SN7407's. They never arrived. (I am in the process of complaining to EBAY.)

The only reason I need the DPDT switching for the hobby level car is to toggle from RC control to autonomous control. I have decided to start off by making wall-racer run on the hobby level car. Once that is going, I will implement the switch over.

Ken