DescriptionThis project is a Microchip PIC microcontroller with an RS232 serial interface on one side and an PS/2 (keyboard or mouse) interface on the other. The PS/2 interface uses bit-banging on a 12F683 device.
Important - All mention of RS232 on this page actually refers to RS232 waveforms operating at 5V TTL levels not +/-12V levels which would destroy the PIC device. An appropriate converter between the two must be used.
The PS/2 interface operates as a host and initialises the keyboard or mouse before going into a never-ending loop of reading the data and sending it to the RS232 interface.
Note: This device does not allow a PS/2 mouse to be used on an computer that only accepts a serial mouse
The circuit is built on stripboard with a DIL packaged IC and conventional through-hole passive components. The PCB is glued into the base of a small box for convenience.
The PIC microcontroller is the only IC and mounted approximately in the centre of the PCB. The RS232 connector is on the right with the PS/2 connector on the left.
PIC SoftwareThe PIC software is written in assembler and this project was the development platform for the PS/2 library functions.
The complete information for this project is available for download. This includes the library functions for the RS232 and PS/2 interfaces as well as the circuit diagram, layout diagram and various C programs. This project is included in the library of PIC code that is available for download.
The circuit diagram is very simple with only the RS232 interface (a connector), PS/2 interface (a connector and 2 pull-up resistors), PIC (IC and decoupling capacitor) and ICSP (socket, 1 diode and 1 resistor).
This simple PCB layout diagram shows the placement of the components on the stripboard. The view is from the top of the PCB, the same as in the photograph.