MTB-2-AVR is an expand module for old MTB-UNI v2 PCBs, MTB-TTL/m v1 modules and MTB-UNIm v2 modules. Its aim is to replace old AT89C2051 CPU originally used these modules with a new ATmega8-like processor. Purpose of the replacement is to allow old modules to communicate over new bus protocol [TODO link].
Replacement: please remove old AT89C2051 CPU and place this board directly to its DIL socket.
Schematics & PCB are designed in Eagle 9.
PCB is prepared to be automatically assembled in JLCPCB.
SMD parts on top side should be assembled. Each SMD part has its LCSC_ITEM
attribute set.
1.0 mm or thinner PCB is advised.
To deploy to old MTB modules:
- Check that RS485 driver has between pins 2 & 8 resistor of maximum value
10k.
- If not, either change resistor to 4k7 or remove RS485 transistor totally and remove resistor too.
- Removing the transistor is slightly better as it will not cause RS485 TX enable on boot. You can also add pull-down (~10k) to driver's DIR pin directly on PCB so when CPU board is removed DIR pin is in defined state.
- Remove DS1706L IC.
The module is designed by Jan Horáček, Model Railway Club Brno.
- MTB project (in Czech)
- MTBbus protocol [TODO]
Content of the repository is provided under Creative Commons Attribution-ShareAlike 4.0 License as openhardware project. You may download any data, contribute to the project, create PCB yourself or even sell it yourself.