Alert pin for nrf52832

[hans_mueller]

Hi,

I am using my nrf52832 board with a MPC9808 sensor and I wanted to use the example code provided in zephyr/samples/sensor/mcp9808

Can you tell me with which pin of the board I need to connect the Alert pin of the sensor?

Because when using the rc = sensor_channel_get(dev, SENSOR_CHAN_AMBIENT_TEMP, &temp); I always get an error code.

Thank you for your help!

[awneil]

hans_mueller said:

I always get an error code

What error code do you get?

[hans_mueller]

I get an error code of -16 which says "Mount device busy". I think this could be the case because of using the wrong pin for the alert?! Do I need to configure the pin before I use it?

[Charlie]

Hi,

You can add an overlay to zephyr\samples\sensor\mpu6050\boards, for example add nrf52dk_nrf52832.overlay for nrf52dk_52832 board as

 &i2c0 {
	mcp9808@18 {
		compatible = "microchip,mcp9808";
		reg = <0x18>;
		int-gpios = <&gpio0 11 (GPIO_PULL_UP | GPIO_ACTIVE_LOW)>;
		label = "MCP9808";
	};
};

Here pin 11 is assigned to detect Alert pin interruption.

After building, you can check pin assignments for mcp9808 from zephyr\samples\sensor\mcp9808\build\zephyr\include\generated\devicetree_legacy_unfixed.h. It look lik

...
/* SDA pin */
#define DT_NORDIC_NRF_TWI_40003000_SDA_PIN          26
#define DT_INST_0_NORDIC_NRF_TWI_SDA_PIN            DT_NORDIC_NRF_TWI_40003000_SDA_PIN
/* SCL pin */
#define DT_NORDIC_NRF_TWI_40003000_SCL_PIN          27
#define DT_INST_0_NORDIC_NRF_TWI_SCL_PIN            DT_NORDIC_NRF_TWI_40003000_SCL_PIN
...
#define DT_NORDIC_NRF_TWI_40003000_MICROCHIP_MCP9808_18_INT_GPIOS_CONTROLLER "GPIO_0"
#define DT_INST_0_MICROCHIP_MCP9808_INT_GPIOS_CONTROLLER DT_NORDIC_NRF_TWI_40003000_MICROCHIP_MCP9808_18_INT_GPIOS_CONTROLLER
#define DT_NORDIC_NRF_TWI_40003000_MICROCHIP_MCP9808_18_INT_GPIOS_PIN 11
...

Just try this configuration to see if the error still exists.

Best regards,

Charlie

[hans_mueller]

Thank you so much!! This is a really good explanation!

[awneil]