PCB designs for an S88 bus for detecting model trains on a track. The Marklin S88 bus is based on a shift register. More information on the Marklin S88 bus can be found here:
- S88-N - s88 over RJ45 (English)
- Digital Bahn.de (Deutsch)
- Marklin S88 Link (PDF manual) (English/Deutsch)
- Avontuur in miniatuur - Terugmelding (Nederlands)
This design uses master and slave boards, connected to a single bus controller (e.g. a Marklin CS or an Arduino). Both boards are suitable for DIY-etching (master: uv-lighting, slave: toner-tranfer). The number of drilling-holes is kept to a minimum. Note: there is no hysteresis on the inputs. This must be implemented in the controller software.
The master board uses 3 74hc165 ICs, resulting in 24 inputs. The master boards can be chained together. Each connector on the master board serves a group of 3 inputs, which are connected via a slave board. All inputs are fitted with pullups. The train wheels connect the inputs to ground when entering a track section.
See the InputModule for the design files of the master board
A small slave board can be mounted close to the tracks, and connects up to 3 track segments. The board features a led for diagnostic purposes.
