RE: Rogue I2C read starting when I force Zephyr to shut down

Glen M — Mon, 22 Jul 2024 17:58:26 GMT

I found it - I guess with my sequence of events I was ending up with the worker task that my pin ISR kicks off pending, and the sleeps I threw in assuming that any pending tasks would run wasn't getting it done. I added a call to k_work_cancel for that task and my unwanted I2C half-read is gone.

RE: Rogue I2C read starting when I force Zephyr to shut down

Glen M — Fri, 19 Jul 2024 20:26:03 GMT

I don't think so. It's a custom driver I made for this device but it appears to just use the i2c_nrfx_twi driver. My .dts file looks like this:

&i2c0 {
compatible = "nordic,nrf-twi";
status = "okay";
pinctrl-0 = <&i2c0_default>;
pinctrl-1 = <&i2c0_sleep>;
pinctrl-names = "default", "sleep";
clock-frequency = <100000>;

tm065049@2A {
compatible = "nordic,tm065049";
int-gpios = <&gpio0 25 (GPIO_ACTIVE_LOW)>;
reg = <0x2A>;
};
};

I've found that this only happens when there's been heavy traffic happening while I'm shutting down, but at this point I feel like I've tried everything to get it to shut off, including lots of k_sleep delays to let things finish.

I even did my best to disable and uninitialize the I2C driver and turn the SDA and SCL lines back into GPIO so it can't send anything, but my best attempt at code to do that apparently doesn't work. I think I have the device definition for my nrfx_twi_t struct wrong.

// GDM I added this function because I found that when shutting down in board.c via pm_state_force, I was getting
// a half a read coming out of the I2C port.
static const struct device *const m_i2c_dev = DEVICE_DT_GET(DT_NODELABEL(i2c0));
static const struct device *const gpio_dev = DEVICE_DT_GET(DT_NODELABEL(gpio0));

void disableI2C(void)
{
const struct nrfx_twi_t *config = m_i2c_dev->config;

nrfx_twi_disable(config);
nrfx_twi_uninit(config);

// Reconfigure the I2C pins as inputs
gpio_pin_configure(gpio_dev, 26, GPIO_INPUT);
gpio_pin_configure(gpio_dev, 27, GPIO_INPUT);

RE: Rogue I2C read starting when I force Zephyr to shut down

Michal — Fri, 19 Jul 2024 20:07:35 GMT

Hello Glen,

Are you using some specific I2C device driver from zephyr by chance?

I wonder if it could be part of the shutdown procedure in the driver for this device.

Best regards,

Michal