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SSCH_1 Serial Speed controller

15 Amp 12 Volt


The SSCH_1 is one of the more advanced speed controllers in the ARM range of products and as normal is packed full of features to help improve your robot. The SSCH_1 achieves a current handling of up to 24 Amps continuously, this is from the use of four 24 Amp MOSFETs in an H-Bridge form. Combined with the power output stage of this speed controller is the use of a MCU (mini computer) that controls the speed of your motor through the use of high frequency PWM, this provides a very smooth and fine motor control. Being a serial speed controller it's possible to control the SSCH_1 from a multitude of devices such as your PC, Basic Stamp 1 and 2, PIC and loads more. The SSCH_1 could even be combined with a serial Modem so you can link your robot to your PC with out the need for wires There is also a Windows PC program that is freely available to control the SSCH_1 speed controller that can be downloaded from this web site(see further down the page for details). The SSCH_1 speed controller can operate on voltages from 10 to 14 volts. It's best combined with a 12 Volt lead acid battery for optimum performance.

The SSCH_1 speed controller is supplied ready made and ready to go from the moment you've hooked the battery and motor up.

Please note that it is highly recommended that you put a fuse in line with the positive power supply (+) to the SSCH_1 speed controller to avoid damage to either the SSCH_1 or your motors or even both.


  • Serial control
  • Up to 15 Amp normal load (using 24 Amp MOSFETs)
  • High frequency PWM motor drive
  • Easy to use
  • Can be stacked, more then one can be put on a serial port
  • Compact size at only 50x60x60
  • Designed for connection straight to a 12 Volt power source (Sealed lead acid batteries!)


These items are now obsolete, we have a new design, which will be in full production soon.

The SSCH_1 speed controller design has been tested to destruction, above are photos of the MOSFETs after having 0.1 Ohm load put on them drawing around 120 Amps, no surprise that they didn't last long as there only rated at 24 Amp. Made a bit of a bang.

The SSCH_1 PC control software

This software has been designed to allow easy control of your SSCH_1 speed controller from a Windows PC. This software is provided free and as such comes with no warranties what so ever. It is also possible to program new Controller numbers from this software. When you buy a new SSCH_1 speed controller you will also be sent this software with speed controller on a CD-ROM.

SSCH_1 data sheet for manual programming and use

Program code (decimal)
Sets 2400 Baud
Sets 4800 Baud
Set 9600 Baud
Baud Rate Reprogram
Controller Number Program
Not used as yet
Motor Forward Select
Motor Backward Select
Not used as yet
Variable speed set


Read Controller number

Code 249 instructs the SSCH_1 to serially send it's Controller number, this is done for easy identification of SSCH_1 units if you forget there Controller number

Controller Program:

To program the Controller (speed controller number) simply send the decimal number 250 to the SSCH_1 speed controller from any PC serial port using a terminal program. After sending this number you will be asked to assign a new Controller number to the SSCH_1 speed controller you should then send a decimal number from 200 to 220. This number is what determines which speed controller the instructions are meant for i.e. 200, 201 or 202 and so on. A maximum of 20 (Controller numbers from 200 to 220) SSCH_1 speed controllers can be connected to one RS232 serial port.

Please note that the default Controller number is 200, if you have just brought a new speed controller from Al's Robotics then this is the Controller number that has been set for the speed controller.


Sending the decimal number 251 will stop ALL speed controllers that are connected to the serial port the instruction was directed too to stop all power output to your motors. Thus acting as an emergency stop for your motors.

Not used as yet:

These are commands that have been allocated for future use, but as yet are not in use and sending these commands to a SSCH_1 speed controller will do nothing.

Motor forward select:

Decimal command 253 sets the SSCH_1 speed controller for Forward motion (i.e. Your motor will go forwards)

Motor backward select:

Decimal command 254 sets the SSCH_1 speed controller for Backward motion (i.e. Your motor will go backwards)

Variable speed set:

These decimal numbers from 0 to 90 sets the speed at which your motor will turn. If you send 0 your motor will not turn but if you send 90 your motor will turn as fast as it can in your chosen direction. And all numbers between these values will give you either a higher or lower speed.

Command sequence and examples:

The order in which these commands are sent to the SSCH_1 speed controller is vital for proper operation. Below is the order in which you must send the codes from your RS232 serial source:

  1. Controller number
  2. Direction select
  3. Variable speed set

Below is an example for a motor going forwards at half speed (45) and a speed controller with the Controller number of 201

Serial send the decimal value "201"

Serial send the decimal value "253"

Serial send the decimal value "45"

Wire connections

Wire Colour
Connect to.
Positive supply, +12 Volts
Negative supply. -. ground, 0 Volts
Motor connection 1
Motor connection 2

Speed controller serial settings:

The SSCR_1 speed controller comes set by default to the following settings:

  • 9600 Baud Rate (can be reprogrammed)
  • 8 Data Bits
  • Parity None
  • 1 Stop Bit
  • No Flow Control

The Baud Rate at which the SSCR_1 speed controller communicates may be changed to one of three settings, 2400 Baud, 4800 Baud and 9600 Baud.
Setting the Baud is a very simple task and is very fail safe. Simply send the decimal number 240, this sets the SSCR_1 speed controller into reprogram mode, you can then send the following decimal number to set the Baud Rate: 24 for 2400 Baud, 48 for 4800 Baud and 96 for 9600 Baud.
It is important that once the SSCR_1 is set into Baud reprogram mode that you only send one of the above numbers, otherwise you will not be able to communicate with SSCR_1. If at boot time the SSCR_1 detects that an invalid Baud rate setting has been programmed into it, it will default back to 9600.

After you have finished reprogramming Baud Rate setting you must restart the SSCR_1 speed controller by removing all power to the board. At the next boot time your new Baud Rate will be implemented.

Example of reprogramming the Baud to 4800:

Serial send the decimal number “240” this sets Baud reprogram mode
Serial send the decimal number “48” this sets the new Baud speed
You will then receive a confirmation from the SSCR_1 that is decimal “255”

Restart the SSCR_1 by removing all power, reconnect power after a few seconds and your new Baud Rate settings will be implemented.

For further information and how to order please send an e-mail to:








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