Onboard i2c fails when adding external i2c sensor

JeppeMariagerLam

Hi guys 🙂 For some weird reason, the onboard i2c devices fail to respond when I add my external i2c sensor. I’ve tested a couple of things, and it seems to be related to the SDA and SCL lines, as if I remove those, the onboard devices work (accel and pcf85063a).

I’m bascially seeing errors like the below in my log:

[00:00:01.319,549] <err> i2c_nrfx_twim: Error 0x0BAE0001 occurred for message 0
[00:00:01.327,667] <err> pcf85063a: Unable to stop RTC. (err -5)

My i2c conf is:

&i2c1 {
    zephyr,concat-buf-size = <256>;
    clock-frequency = < I2C_BITRATE_STANDARD >;
    status = "okay";

	accel0: lis2dh@18 {
		compatible = "st,lis2dh";
		reg = <0x18>;
		irq-gpios = <&gpio0 29 GPIO_ACTIVE_HIGH>, <&gpio0 30 GPIO_ACTIVE_HIGH>;
		disconnect-sdo-sa0-pull-up;        
	};

	pcf85063a: pcf85063a@51 {
		compatible = "nxp,pcf85063a";
		reg = <0x51>;
	};
};

Any pointers on where go start debugging this?

jaredwolff

@JeppeMariagerLam did you take a look at the actual I2C signals themselves on an osilliscope? I use a lighter set of pull-ups on the nRF9160 Feather. You may need to add additional ones depending on how much captivate load your other sensor(s) have.

AchimKraus

Maybe you tell us, which sensors you want to use. One common point is the voltage the device operates and the voltage the I2C interface operates. For the feather the I2C voltage it’s 3.3V.