We were asked by a number of customers to design a basic controller that was small, inexpensive, and could be easily programmed to do a variety of tasks. The SST-31 is the result. Based on the power section of our proven Porter 5, it uses a small Picaxe microcontroller to provide a range of functions and capabilities usually only found on larger, more expensive controllers. Designed with four separate input / output ports the SST-31 provides great flexibility for more advanced motor control projects that require input from external switches or sensors, or to have timer functions included [e.g. windscreen wiper control]. Apart from the motor supply there is one 5V output that can be used to drive a relay or LED, and there is also a serial output that can be used to drive a LCD display.
For basic applications the SST can be used out of the box with it’s default values, but by accessing its programmable capabilities a host of possibilities is opened up. We selected the Picaxe chip because it is easy to program without specialist equipment or complex software. We’ve made the operating software completely open source to allow and encourage development in a wide variety of power control applications.
- 12V – 35V
- Up to 30A depending on cooling.
- Single direction
- Easily programmed if required via free Picaxe software
- Three control inputs, two with output capability
- On / off “ignition” input
- Picaxe 08M2 microcontroller
- Ready-made, open source software versions available for the following functions;
- Open loop PWM control using a potentiometer or voltage input [like the majority of other 4QD controllers].
- Softstart operation via switch or ignition input.
- Closed loop RPM control using a hall effect or other sensor [coming soon].
- The software can be easily adapted to work with the 4 – 20 mA current loop process control standard.
- Die-cast box provides protection and heatsink function [can be sealed if water resistance is required].
The SST-31 is supplied with one software version pre-installed [choose the version in the drop down box]. The code for all the versions is available on the software tab, and can be downloaded and modified by the user as required. Each version has been written with well defined and documented variables allowing the behaviour to be tailored to the application. Flashing the software into the SST-31 requires a PC with a USB port, a Picaxe programming lead and our conversion cable. [add links]
There are 3 control inputs which can be used in a variety of ways e.g. for a potentiometer or voltage input, to monitor system parameters such as temperature or pressure, or to sense a brake switch. Two of the three inputs can also be used as outputs if required e.g. to drive a display, solenoid or alarm.
Picaxe development software is free to download and allows users to either modify the existing software or to develop entirely new applications. We have written the standard software versions using the BASIC language, which gives fine control over all the variables. A simplified version of each has also been created using the Picaxe flowchart system which is easier for non-programmers to understand. If you can draw a flowchart then you can program the SST-31. For volume orders 4QD can develop the software.
The SST-31 use the Picaxes’ built in PWM function to give the user full control over the frequency and duty cycle of the PWM output. The frequency can be adjusted down for enhanced current capability.
A Picaxe LCD module can also be added to display information, messages, or system variables in real time.
Note; The SST-31 has been designed to be a low cost, simple controller. As such certain features found in our other controllers are not present, these include
- Regenerative braking
- Current limiting
- Over temperature protection
- Reverse polarity protection
- Over voltage protection
- Pot fault protection
- High pot lockout [can be added in software]
The user should take these into account when designing the system.