Multi-Purpose I/O Board
This is a multi purpose input / Output board that can be used directly with aPC via a USB port or with a Microcontroller either using a serial interface or I2C interface.
- USB interface for connecting to a PC. When connected this will present itself as a COM port and communication can commence via HyperTerminal or other terminal software (software included in the resources pack). VB can also be used using the MSComm component or indeed any program that can communicate via the COM port
- On board voltage regulator protects the PC from short circuits. Also when used with a microcontroller the input voltage can be up to 10V.
- Input connector that can accept either serial OR I2C
- OPTIONAL jumper to disconnect the USB chip when used with a microcontroller
- Standard FTDI USB to Serial chip has standard drivers for PC,MAC and Linux. The drivers are already built into Linux.
- Four 10 bit analog to digital inputs with an accurate reference voltage that can be set to 1.024V, 2.048V and 4.096V
- Two Digital to analog outputs that can be set to give an analog output from 0 to +V in 63 steps.
- Two relays outputs up to 10A @ 250VAC and 10A 24V DC
- An 8 port digital switch using the ULN2803 Darlington output. This is capable of switching up to 1/2 Amp per port. and Voltages up to 50V.The o/p is pulse width modulated and so the output power can be varied.
- This is connected to the digital switch and can either input or output 8 channels.
Resourceszip file , includes free terminal software
The device is operated serially either via the USB or directly through connector (3). Initially the device will recognise the Baud rate (from a fixed set) when it receives the first carriage return. This can be 'fixed' by using the system settings. There is also an acknowledge mechanism that will enable the device to operate efficiently without connecting the hardware handshake line (CTS/RTS).
Commands are based on the VT100 command set that use escape codes. For example to turn on relay A the following would be sent to the device:
to turn it off would be:
All of the commands follow the same pattern.
The device can recognise when an I2C bus is connected and automatically switch to that mode. The default address is 0x64 (8 bit) 0x32 (7 bit) but can be changed to any address within the range 2 - 0xfe by the user. When using I2C the escape codes are replaced by single byte commands.
There is an 8 bit wide digital input and output port. The output is connected to a Darlington driver for driving high power devices such as motors and solenoids. The output on each channel has an independent pulse width modulation that can be varied form completely off (0) to fully on (255) in 255 steps. This could vary the brightness of lamps or speed of motors.
Analogue to Digital
There are 4 ADC channels that are continually scanned by the firmware. In addition there is a built in precision voltage reference that can be set to one of three levels, 1.024V, 2.048V and 4.096V. The setting is simply a matter of issuing a command.
Digital to Analog
There are two analog outputs that can be digitally controlled in 64 steps to give a range of output from 0V to 5V.