PBP projects for R/C models

[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

[Kenjones1935]

My long awaited SN7407N's arrived today by priority USPS First Class mail.

I thought the package was empty. I could not feel the DIPS.

They are D package. I did not know this size dip existed. I can barely see the individual pins. They do not fit into any of my .100" grid prototype boards.

I think I need to specify J or N. Is there a difference from the prototyping point of view?

Ken

[rmteo]

This will tell you SN7407

[Byte_Butcher]

Yep, the "D" package is SOIC (Small Outline Package)

You would want the "N" package for DIP. According to the TI data sheet, the "J" package is obsolete.

Don't feel bad, You ain't the first one to order parts in the "wrong" package.
I've got a few 16F727's sitting here that I meant to order in a nice compact 44-tqfp package and instead I ended up with these HUGE 40 pin DIP's. Cripes, they're bigger than the whole circuit board they're supposed to go on!



steve