View source for VisionSOM-STM32MP1 sensors demo

{{PageHeader|VisionSOM-STM32MP1 sensors demo}} __toc__

[[File:VisionSOM-STM32MP1_sensors_demo.png|800px|center]]

The SoMLabs sensors demo application for VisionSOM-STM32MP1 module and VisionCB-STM32MP1-STD board is the example of simple signal measurement and data presentation in a graphical user interface. The application reads the acceleration data from the LSM6DS3 sensor connected to the I2C bus and the analogue signal samples collected by the on-chip ADC. The results are presented on the Qt interface built with the QML and QtCharts libraries.


[[File:VisionSOM-STM32MP1_sensors_demo.mp4|800px|center]]

== Hardware configuration == 

=== ADC ===

The ADC needs to be enabled in the device tree since it is not configured in the default system images for VisionSOM-STM32MP1. Moreover, the timer 2 is enabled and used later for the ADS triggering. The following files in the mx directory need to be modified:

* kernel/stm32mp157a-visionsom-dsi-mx.dts

<pre>
 &pinctrl {
 	u-boot,dm-pre-reloc;

	adc_pins_mx: adc_mx-0 {
		pins {
			pinmux = <STM32_PINMUX('B', 1, ANALOG)>; /* ADC1_INP5 */
		};
	};

	adc_sleep_pins_mx: adc_sleep_mx-0 {
		pins {
			pinmux = <STM32_PINMUX('B', 1, ANALOG)>; /* ADC1_INP5 */
		};
	};

</pre>

<pre>
&adc{
	pinctrl-names = "default", "sleep";
	pinctrl-0 = <&adc_pins_mx>;
	pinctrl-1 = <&adc_sleep_pins_mx>;
	status = "okay";

	/* USER CODE BEGIN adc */

	vref-supply = <&vdd>;
	status = "okay";
	adc1: adc@0 {
		st,adc-channels = <5>;
		st,min-sample-time-nsecs = <10000>;
		status = "okay";
	};

	/* USER CODE END adc */
};
</pre>

<pre>
&timers2{
	status = "okay";

	/* USER CODE BEGIN timers2 */

	/delete-property/dmas;
	/delete-property/dma-names;

	pwm {
		status = "okay";
	};

	timer@1 {
		status = "okay";
	};

	/* USER CODE END timers2 */
};
</pre>

* u-boot/stm32mp157a-visionsom-dsi-mx.dts

<pre>
 &pinctrl {
 	u-boot,dm-pre-reloc;
 
	adc_pins_mx: adc_mx-0 {
		pins {
			pinmux = <STM32_PINMUX('B', 1, ANALOG)>; /* ADC1_INP5 */
		};
	};

	adc_sleep_pins_mx: adc_sleep_mx-0 {
		pins {
			pinmux = <STM32_PINMUX('B', 1, ANALOG)>; /* ADC1_INP5 */
		};
	};
</pre>

<pre>
&adc{
	pinctrl-names = "default", "sleep";
	pinctrl-0 = <&adc_pins_mx>;
	pinctrl-1 = <&adc_sleep_pins_mx>;
	status = "okay";

	/* USER CODE BEGIN adc */

	vref-supply = <&vdd>;
	status = "okay";
	adc1: adc@0 {
		st,adc-channels = <5>;
		st,min-sample-time-nsecs = <10000>;
		status = "okay";
	};

	/* USER CODE END adc */
};
</pre>

<pre>
&timers2{
	status = "okay";

	/* USER CODE BEGIN timers2 */

	trigger@0 {
		status = "okay";
	};

	/* USER CODE END timers2 */
};
</pre>

* u-boot/stm32mp157a-visionsom-dsi-mx-u-boot.dtsi


<pre>
		CLK_ADC_PLL4R
</pre>

<pre>
 	pll4:st,pll@3 {
		cfg = < 3 98 5 7 7 PQR(1,1,1) >;
 	};
</pre>

* tf-a/stm32mp157a-visionsom-dsi-mx.dts

<pre>
		CLK_ADC_PLL4R
</pre>

<pre>
 	pll4:st,pll@3 {
		cfg = < 3 98 5 7 7 PQR(1,1,1) >;
 	};
</pre>

<pre>
 &etzpc{
 	st,decprot = <
	DECPROT(STM32MP1_ETZPC_ADC_ID, DECPROT_NS_RW, DECPROT_UNLOCK)
	DECPROT(STM32MP1_ETZPC_TIM2_ID, DECPROT_NS_RW, DECPROT_UNLOCK)
</pre>

=== LSM6DS3 ===

The LSM6DS3 sensor is connected to the I2C4 bus which is already configured for the touchscreen. However a new subsection needs to be added to the &i2c4 device in order to register correct driver.

* kernel/stm32mp157a-visionsom-dsi-mx.dts

<pre>
	lsm6ds3@6a {
		compatible = "st,lsm6ds3";
		reg = <0x6a>;
	};
</pre>

Finally, the driver needs to be compiled with the kernel (or as a module) in the kernel configuration file:

* stm32mp157a_visionsom_mx_defconfig

<pre>
CONFIG_IIO_ST_SENSORS_I2C=m
CONFIG_IIO_ST_SENSORS_SPI=m
CONFIG_IIO_ST_SENSORS_CORE=m
CONFIG_IIO_ST_LSM6DSX=m
CONFIG_IIO_ST_LSM6DSX_I2C=m
CONFIG_IIO_ST_LSM6DSX_SPI=m
</pre>

== ADC configuration ==

The ADC is configured within the application using the iio subsystem. The following values are written to the configuration files in order to obtain the 1kHz sampling frequency on channel 5 with 128 samples watermark:

<pre>
echo 1000 > /sys/bus/iio/devices/trigger0/sampling_frequency
echo 1 > /sys/bus/iio/devices/iio:device0/scan_elements/in_voltage5_en
echo tim2_trgo > /sys/bus/iio/devices/iio:device0/trigger/current_trigger
echo 128 > /sys/bus/iio/devices/iio:device0/buffer/watermark
echo 256 > /sys/bus/iio/devices/iio:device0/buffer/length
echo 1 > /sys/bus/iio/devices/iio:device0/buffer/enable
</pre>

The raw ADS readings are obtained from the file: ''/dev/iio:device0''

== LSM6DS3 configuration ==

The LSM6DS3 sensor is ready to use after system boot. The application configures the sampling frequency:

<pre>
echo 416 > /sys/bus/iio/devices/iio:device0/sampling_frequency
</pre>

The sensor raw readings can be obtained from the files:
* /sys/bus/iio/devices/iio:device0/in_accel_x_raw
* /sys/bus/iio/devices/iio:device0/in_accel_y_raw
* /sys/bus/iio/devices/iio:device0/in_accel_z_raw


== Application binary ==

The application compiled binary is available for download: [[Media:VisionSOM-STM32MP1_sensors_demo.zip|VisionSOM-STM32MP1_sensors_demo.zip]]