R/C and Raspberry Pi Control

Help & Support Robot Parts
1

Hi;

I am building a motorised chassis using 2 x wheelchair motors and have just received a 2 x 32Amp Sabertooth Motor Driver.

Requirements
What I would like to achieve is to have 2 forms of control:

  1. R/C control to provide manual control of the chassis.

  2. Autonomous control so that the chassis can drive itself.

I would like to use a Raspberry Pi for the Autonomous control but have read that to do so I may need additional hardware such as a logic level shifter?
I have read the manual and it looks like with the 32Amp version the controller can be controlled via a Raspberry Pi over Serial using a USB connection?

It would also appear that in User Mode two forms of control are possible, R/C and Serial however when in this mode can the Serial connection be via USB or does the Micro Controller need to be connected via S2.

Question
Can anyone help by advising me as to what would be the best / simplest / neatest route to achieve what I am trying to do. I would rather use a Raspberry Pi as I already have one lined up but I will buy an Arduino (not sure which type Nano or Uno?) unless it is easier to just fit a Logic Level Shifter?

Additional Info
I have also found out the following:

My intention was to hook up an R/C receiver to the Sabertooth for the R/C side (very simple) and use a Raspberry Pi hooked up via a serial interface however after doing some research it would appear that controlling the Sabertooth Serial using a Raspberry Pi would require additional hardware such as a level shifter due to the Pi Serial output being 3.3v and the input required by the Sabertooth being 5v. Some information I have read is ambiguous say that you may get away with 3.3v ?

Anyway I am looking for a solution to control the Sabertooth using a Raspberry Pi via serial (possibly using an Arduino as an interface but I have done this before with difficulty - it worked but with no fine control).

Regardless of the info I have found on reading the Sabertooth manual it does however suggest that the Sabertooth can be controlled using a Raspberry Pi by connecting it via USB - USB. A quote from the manual:
“USB is the easiest way to interface to PCs or advanced microcontrollers like a Raspberry Pi”

The Sabertooth also has a ‘User Mode’ in this mode the controller can accept two input methods such as R/C and Serial. The S2 input is connected to channel 5 on the R/C receiver and acts as a switch to set the mode to R/C or Serial control. What I am not clear about is whether this mode would work with a Raspberry Pi connected via USB or whether it would only work if connected to S1. S1 one is the Serial RX port so in this mode the Sabertooth could only receive signals, which I guess is what is needed.

2

Hi,

You can interface the Sabertooth Dual 2x32A 6V-24V Regenerative Motor Driver with a Raspberry Pi, you would need a level shifter as this one.
The easier way to do this would be to connect it through USB, as you mentioned, so that you will avoid interfacing a level shifter as USB mode uses the same commands as the serial mode.
We have contacted Dimension Engineering to verify if USB (Raspberry Pi) and R/C mode can be used simultaneously in the “User Mode” and if RC’s channel 5 can switch between those two modes.
We will post their answer here as soon as they reply.

Best Regards,

3

Many thanks for your informative response and also for checking whether the USB / R/C combo will work.
I am now researching how to send serial commands from the Pi.
I think I have done it before to talk to an Arduino which was connected to 2 x DC Motors via an L298N Motor Driver Board

4

Hi Jonny,

Here is the reply we’ve got from Dimension Engineering :