PCB Review - I2C with MCP23017 for existing mosfet board
Hi everyone. I am planning to replace the 10 GPIO header pins on my current pump controller board with a GPIO extender, such as the MCP23017, so the control goes over I2C.
The "GPIO" variant (mosfet/pump/12V circuits) was already reviewed and produced; the change from direct GPIO -> I2C control is new here and is the focus for the review.
The plan is to go from a Raspberry Pi (or another SBC with I2C) to the board via I2C, and potentially daisy-chain another device, like a NAU7802, for scale control.
Since I do not have a strong background in this whole PCB topic, I mostly have dangerous half-knowledge and would love some feedback. Things I am not sure of:
- Adding a (100nF?) capacitor to reset for stabilisation
- Adding a pull-up (4.7k?) to SDA/SCL; I think RPi already has some?
- Is this daisy-chaining okay
- General (routing/schematics/other) mistakes a rookie makes
The PCB (pcb/cbb-i2c) source is also available on GitHub if anyone prefers looking into it over the editor.
Thanks in advance for your time.