Rough draft of an I2C expansion card for the Commander X16
I don't have any real hardware, and haven't fabbed this. So there's little reason to believe it works.
- Features
- PCA9548A I2C eight port multiplexer, so you can use a lot of I2C devices without loading the bus down. Also lets you use multiple identical devices, which would otherwise have conflicting addresses.
- Four I2C ports are brought out SparkFun Qwiic-style, with 3.3V power.
- Why that connector? Sparkfun has a lot of Qwiic hardware, and Adafruit as a bunch of STEMMA QT hardware, which is compatible. Some other companies have some similar products. This gets you dozens of compatible IO devices in one fell swoop.
- Three are headers on the board, with 5V power, for use "inside the case"
- Last port is on a PCA9615 differential I2C transceiver, for very distant I2C devices.
- It provides 3.3V and 12V.
- Intended to be compatible with the Sparkfun QwiicBus Endpoint
- One mandatory 3.3V regulator for the external I2C ports.
- You can add one or two other additional regulators, to provide more power to your I2C devices.
I'll revisit and revise this as more docs come out, and whenever I get real hardware.