I am using a microcontroller (One of TI’s C2000) to control the tri-track. I’m pondering between two possibilities…
a) using analog mode: Use a PWM output, switch it to 0-5V with a MOSFET, then pass it through a RC filter to get an analog voltage then through OP AMP to counter the high impedance of the RC circuit (see attached picture- MCU replaced with function generator for simulation purpose)
b) using only a PWM and maybe a FET for 5V too (so much simpler?) to make it act like a RC Controller. But I don’t know exactly how they work. I’ve seen like: 1 pulse every 10-20ms at about 10-15% Duty cycle. Is it really that simple? Which parameter makes the speed change?
To me, I would go with b) as I think the Analog mode is to indirect…
Yes you need to generate a pulse about every 20ms (50 times per second), where the width of the pulse width controls the speed of the motors. If the pulse width is about 1500us the motors will be rest. The exact zero point may slightly different from Sabaertooth to Sabertooth, but it is right around 1500 so assume 1500. If your pulse width is > 1500 the motor will go one direction. The farther from 1500 the faster it will go. Likewise if less than 1500 it will go the opposite direction. Again the farther from 1500 the faster… I don’t remember the actual range of pulses that that the Sabertooth process, but my guess is it is something like: 750-2250, but it may also be a smaller range. You can easily experiment to figure it out…
I personally don’t know. Some processors or devices have no problem with the lower voltage, but some do. If you have the hardware I would simply try and see…
Well, in case anyone wondered, I tried using RC Mode with my microcontroller’s 3.3V PWM plugged in directly and though I don’t have perfect control yet, the Sabertooth responds. I just wonder if it can put a strain on my MCU’s output on the long term. I don’t think it needs much current.
It is just sad that therer is no electrical specifications about the sabertooth (not much at least). I know it’s mostly meant for the hobbyist that might not know much about electronics, but some infos about input/output characteristics, high/low voltage requirements and more would be appreciated.
