PBP projects for R/C models

[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 According to the TI data sheet, the "J" package is obsolete.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

[Kenjones1935]

The hobby car using HPWM seems to behave correctly.

I need to calibrate the wheel torques associated with the various PWM pulse sizes. The steering servo seems slow. I know it can work well because it did so with the radio receiver in charge.

My proto is too fragile to run the car on the floor. I have it up on a stand making the wheels free. It runs on its own 7.2V battery unattached to the USB port. I can make it think there are walls near by using an oak cutting board to fool the proximity detectors.

Once this thing makes sense I will post a video.

Ken

[Kenjones1935]

Suddenly and without warning my PICkit2 programmer is not doing its job. See this picture. Any ideas? I can get rid of the Code Protect by erasing. Then it comes back. The memory error just starts happening...



NUTS! Or am I repeating myself.

Ken

[mackrackit]

Maybe it got turned on here?