P112 is a general purpose GPIO board based on PIC16F873 micro-controller.
The board provides twelve GPIO circuits that can be configured either as input or output depending of the component mounted. Inputs are opto isolated, outputs are reed relay contact closures.
The board also provides a serial port with a RS485/422 driver. This may be useful if you plan to connect more that one P112 boards in a RS485 bus, or a single board controlled by a computer via RS422.
To help you in the development of your Firmware, a "framework" is provided. This is an skeleton program written in assembly that takes care of GPI reading and de-bouncing, interrupts handling and more, so you can focus on your application-specific code. See section "Firmware" for details.
An "ICSP" connector (In-Chip-Self-Programming) is available in the board to upload your object code to the MCU memory.
 Assembling the boardThe printed circuit board is designed so you can chose the desired configuration of GPIOs by mounting the appropriate components for each circuit. For GPI, mount the opto isolator and the two associated resistors. For GPO, mount the relay and the associated diode. Never mount the two of these options in the same GPIO circuit.
You are not forced, though, to use opto isolators for inputs or relays for output. If a direct connection is desired, replace those components with jump wires (pins 2,4 of the opto isolator footprint). If it is an input, you may want to also mount the 10K pull up resistor.
The RS485/422 driver (U2) is optional. If you don't plan to make use of the serial port, you can leave the footprint empty as well as that of the header connector J2. Same with the ADDR header (S1) if you have no plans for configuration jumpers.
|
|
