need help with r/c model electronic speed control

[raimain]

hi im new to this forum and in bad need of help.

i am wanting to make a esc for use with my model tank that im working on, but am unsure where to start.

i was thinking that it would need;

2 motor outputs that can provide upto 7.2v @ upto 12amp.
2 inputs that collect the pwm info from the reciever.

im not sure which chip would be best to use and i dont really know much about the writeing of the code for the chip, but i do have a programmer to use to program the chip.

i hope that someone can help

thanks

raimian

[sayzer]

PIC16F690 could be a good choice to drive two motors in both directions.

Check its data sheet first, have some idea and come back here again


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[Acetronics2]

Hi, RainMan

In my drawers, I have a Twin Esc for big boats ...

Throttle drives the two motors ... AND Ailerons drive the Left/right motors differential.

I know tanks have two Throttle levers ... but driving is much easier that Way !!!

Hardware will be a little "heavy" for your purpose ( 50 continuous Amps, 3000 Hz, relay reversing, and Fiber Optics coupling to power units ), but soft may be greatly re-usable.

A little notice ... listing is 1400 Basic lines ( but with the blank lines !!! ... so, let's say 700-800 PbP program lines ...)

For info, to be comfortable, you need Two Processors w/PWM ( twin sticks driving ??? ), OR one with 2 PWM outputs.

I used a 16F876 ... but less than half memory is necessary !!!

Alain

[raimain]

i was thinking 1 chip would be better so it can do (channel mixing) to mix the throttel and the steering.

the motors that im using are standard 540 motors and standard 7.2v r/c batteries.

i had a look around and there is 1 esc in a microchip app note but its for a r/c plane so it has no reverse(AN847), but will probly be usefull for getting the code for reading the pwm from the reciever from.

i also have a load of TIP120 NPN darlington transistors to use, but not sure if they are the right sort for this project.

i hope that someone can help me with this project

[Dave]

raimain, I thought you might need some assistance so here is a circuit I came up with about 8 or so yeard ago to drive a BARBIE Hotwheels car for my daughter. The circuit as built can supply 300 amps surge and as built has no heat sinks at all. All you need is 1 pwm output and a direction bit. HTH

Dave Purola,
N8NTA

[raimain]

thanks for the circuit diagram, now i just have to build it.

does anyone know which chip would be best for this and how do i find the code that will work propely for this project.

thanks again

raimian

[Dave]

raimain, It may be a bit complex so here is the jistofit, I pulled every thing out but the important stuff. The variables SPD and DIR are 10 bit inputs from say a joy stick corresponding to Y and X. With two of the circuits I previously posted you can make a tank type device and operate it with 1 joystick. Pressing it forward to move forward and pulling it in reverse to travel in reverse. Naturally moving it left or right will the device turn left or right. The null position for the variables is 511 for no output from the H bridge.
This code was originally written for a 16F876 but updated for 18F252.
I'm sorry I can't give you more but that's business........ HTH....

Dave Purola,
N8NTA