Active adapter for connect PS/2 mouse to the RS232C serial port.
With this adapter you don't need to search and buy rare and expensive old serial mouse for your retro computer. Any mouse with PS/2 interface and most of simple USB-mouses will operate as Microsoft or Logitech serial mouse.
- Only 16 parts including PCB and sockets.
- Small device size.
- Simple one-layer one-side PCB.
- No SMD components.
- Common and cheap microcontroller.
- Selectable 3-button mouse protocol (Microsoft or Logitech).
- Open-source electronics and firmware.
Adapter is based on ATtiny25 microcontroller, but PCB layout and firmware source are fully compatible with whole 25/45/85 series without any changes.
There are two variants of PCB layout: with PS/2 and USB mouse socket. Both they have one-layer one-side design without VIA covering and fully ready even for manual tracing.
They are fully identical except an mouse socket type.
Note what USB version does not provide true USB host. The USB socket is only used as built-in PS/2-to-USB passive adapter.
Only universal USB+PS/2 mouse will work!
Usually it is a simple office mouse with two buttons and one clickable wheel.
Jumper is used to switch 3-button mouse protocol extensions between Microsoft and Logitech style. The 1-2 position (close to the mouse socket) mean Microsoft, 2-3 respectively Logitech. Jumper is hotplug-ready.
Since RS232C port does not provide power supply enough to feed most of PS/2 mouses, the standart "floppy-style" 4-pin MOLEX plug is used as power source (+5V line only).
Please see also README of schematic diagramm and README of firmware section.