- PIC-DIO Instruction Manual (Mini-DIO is a PIC-DIO without the LPT command)
- Mini-DIO Schematic Diagram
- Mini-DIO Firmware File for Microchip 16F84 (V1.00)
This may be re-inventing the wheel, but a tiny & inexpensive PIC based DIO Link made a lot of sense for me. An 18 pin package plus the 75176 makes for quite a tiny interface. So I modified the PIC-DIO firmware to fit into a Microchip 16F84.
NOTE! Because of the limited RAM available on the 16F84, this DIO CANNOT be connected to a parallel printer (The LPT()= XPRESS command is ignored). See the PIC-DIO page for that functionality. All other DIO-Link features (byte and bit I/O sets and queries) are supported with this chip.
This chip DOES have a strobe line for interfacing to other electronic devices. These tiny devices allow you to easily spread digital I/O all over your RS-485 network. They are perfect for things like alarm inputs, relay outputs, etc. For complete information about the Mini-DIO, consult the instruction manual.
I have no plans to design a PCB for the Mini-DIO since the PIC-DIO performs the same function, is quite small (1.5in x 2.5in), has status LED capability, and is easier to configure. If you wish to really roll your own, you can download the firmware hex file for programming.
