Reply To: OpenMV camera sending cap counts to an old Intel Edison over UART: nothing arrives

I fought the Edison breakout for a lab last year. Opening /dev/ttyMFD1 isn’t enough on that board: pins 0 and 1 go through a pin multiplexer and the level shifters, and until those are set up the UART isn’t connected to the header at all, the pins are plain GPIO. That’s why it opens fine and reads nothing.

The easy way is the mraa library, which sets the mux for you when you open the UART by its board number:

import mraa
u = mraa.Uart(0)            # pins 0/1 on the Arduino breakout, sets the mux
u.setBaudRate(115200)
u.setMode(8, mraa.UART_PARITY_NONE, 1)
while True:
    if u.dataAvailable(1000):
        line = u.readStr(64).strip()     # "caps_ok=1823;caps_rej=12"
        vals = dict(kv.split("=") for kv in line.split(";"))
        # add to the payload the Edison already sends:
        payload["caps_ok"] = int(vals["caps_ok"])
        payload["caps_rej"] = int(vals["caps_rej"])

Also check the wiring is crossed: OpenMV TX to the Edison’s RX (pin 0), OpenMV RX to the Edison’s TX (pin 1). Pin 0 is RX on the breakout, so if what you wrote is exactly how it’s wired, swap them.