Short update.
I've completed 4 from 5 PCB's (including documentation and detailed BOM information in Kicad files such as MPN, Datasheets and links where they could be purchased, so far Mouser as they are available globally). I plan to order these boards from jlcpcb.com but since shipping costs are relatively high, I want to order all 5 different designs at once to test them, but then with fast delivery.
Completed are:
Main PWM module (8 * 10V output) with interface to a daughter board
1st daughter board extends with an additional 8 outputs, with voltage selectable between 5, 10 and 12V
2nd daughter board with 2 L293D motor drivers able to power 8 dose pumps with external power supply for the motors (note that only 1 daughter board can be added to the main PWM module with max 16 outputs in total). I've assumed that only 1 motor direction is required.
An I2C rail to connect multiple I2C modules to the Raspberry
The address of the main PWM module can be set, so multiple PWM modules can be used (Ranjib's preference to be flexible). So outputs would be almost unlimited
Pending is the HAT for the Raspberry. This HAT should have the remaining interfaces:
-Connection to a relay board(s) (ULM2803)
-Connection to DS18B20 temperature sensors
-Connection to optical ATO sensor
I would like to change the connectors to differentiate between the different functions, but as this would require much time (different dimensions), I want to test the present versions first and then start a redesign (smaller). So far only the PCA9685 is SMT size as it's only available in that housing.
Beside the BNC (probe's), any interface I'm missing?