add VEML6075 driver

4 files changed, 188 insertions, 0 deletions

diff --git a/include/driver/veml6075.h b/include/driver/veml6075.h
new file mode 100644
index 0000000..4604b12
--- /dev/null
+++ b/include/driver/veml6075.h
@@ -0,0 +1,84 @@
+/*
+ * Copyright 2021 Daniel Friesel
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+#ifndef VEML6075_H
+#define VEML6075_H
+
+#include <stdint.h>
+
+/**
+ * Driver for VEML6075 UV Sensor.
+ */
+class VEML6075 {
+	private:
+		VEML6075(const VEML6075 &copy);
+		unsigned char const address;
+		unsigned char txbuf[2];
+		unsigned char rxbuf[2];
+
+		/*
+		 * Calibration data from <https://cdn.sparkfun.com/assets/3/9/d/4/1/designingveml6075.pdf>,
+		 * used to remove the visible and infrared response from UVA / UVB readings.
+		 */
+		const float uva_a_coef = 2.22;
+		const float uva_b_coef = 1.33;
+		const float uvb_c_coef = 2.95;
+		const float uvb_d_coef = 1.74;
+
+		/*
+		 * Datasheet values for counts → µW/cm² conversion at 50ms integration time.
+		 * I'm not sure whether this is before or after adjusting for visible and IR response.
+		 */
+		const float uva_counts_per_uwcm2 = 0.93;
+		const float uvb_counts_per_uwcm2 = 2.1;
+
+		/*
+		 * Responsivity for UV Index calculation from <https://cdn.sparkfun.com/assets/3/9/d/4/1/designingveml6075.pdf>.
+		 * Used after visible/IR compensation.
+		 */
+		const float uva_uvi_response = 0.001461;
+		const float uvb_uvi_response = 0.002591;
+
+		bool readUVCounts(float *uva, float *uvb);
+
+	public:
+		/**
+		 * Create a new VEML6075 object for the specified I2C address.
+		 * This is a no-op; the sensor is not initialized. In its default
+		 * configuration, it takes a light reading every 800ms and uses
+		 * auto-ranging to select a suitable measurement range.
+		 *
+		 * @param addr I2C address of light sensor, default 0x4a
+		 */
+		VEML6075(unsigned char const addr = 0x10) : address(addr) {}
+
+		/**
+		 * Initialize VEML6075 to power on, normal mode, normal dynamic, 50ms
+		 * integration time.
+		 * @return true if initialization was successful.
+		 */
+		bool init();
+
+		/**
+		 * Read UVA/UVB irradiance.
+		 * @param uva UVA irradiance [µW/cm²]
+		 * @param uvb UVB irradiance [µW/cm²]
+		 * @return true if readout was successful.
+		 */
+		bool readUV(float *uva, float *uvb);
+
+		/**
+		 * Read UVA/UVB Index. 0 is no UV, higher values indicate increased UV exposure.
+		 * The overall UV index is mean(UVA Index, UV Index) == (UVA Index + UVB Index)/2.
+		 * @param uva UVA Index
+		 * @param uvb UVB Index
+		 * @return true if readout was successful.
+		 */
+		bool readUVI(float *uva, float *uvb);
+};
+
+extern VEML6075 veml6075;
+
+#endif
diff --git a/src/app/datalogger/main.cc b/src/app/datalogger/main.cc
index 6cdba9e..9083825 100644
--- a/src/app/datalogger/main.cc
+++ b/src/app/datalogger/main.cc
@@ -54,6 +54,9 @@
 #ifdef CONFIG_driver_scd4x
 #include "driver/scd4x.h"
 #endif
+#ifdef CONFIG_driver_veml6075
+#include "driver/veml6075.h"
+#endif
 
 void loop(void)
 {
@@ -195,6 +198,17 @@ void loop(void)
 	kout.printf_float((100.0 * scd4x.rawHumidity) / 65536);
 	kout << " %" << endl;
 #endif
+
+#ifdef CONFIG_driver_veml6075
+	float uva, uvb;
+	if (veml6075.readUV(&uva, &uvb)) {
+		kout << "VEML6075 UVA: " << uva << " µW / cm²" << endl;
+		kout << "VEML6075 UVB: " << uvb << " µW / cm²" << endl;
+	}
+	if (veml6075.readUVI(&uva, &uvb)) {
+		kout << "VEML6075 UV Index: " << (uva + uvb)/2 << endl;
+	}
+#endif
 }
 
 int main(void)
@@ -299,6 +313,10 @@ int main(void)
 	scd4x.start();
 #endif
 
+#ifdef CONFIG_driver_veml6075
+	veml6075.init();
+#endif
+
 	arch.idle_loop();
 
 	return 0;
diff --git a/src/driver/Kconfig b/src/driver/Kconfig
index 4b3693c..3ff88e7 100644
--- a/src/driver/Kconfig
+++ b/src/driver/Kconfig
@@ -95,6 +95,10 @@ config driver_scd4x
 bool "Sensirion SCD4x CO2 Sensor"
 depends on meta_driver_i2c
 
+config driver_veml6075
+bool "VEML6075 UV Sensor"
+depends on meta_driver_i2c
+
 config driver_sharp96
 bool "sharp LS013B4DN 96x96px Transflective LC Display"
 depends on ( arch_msp430fr5969lp || arch_msp430fr5994lp ) && meta_driver_spi
diff --git a/src/driver/veml6075.cc b/src/driver/veml6075.cc
new file mode 100644
index 0000000..a3e41f6
--- /dev/null
+++ b/src/driver/veml6075.cc
@@ -0,0 +1,82 @@
+/*
+ * Copyright 2020 Daniel Friesel
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ *
+ * Driver for VEML6075 Ambient Light Sensor.
+ */
+#include "driver/veml6075.h"
+#if defined(CONFIG_meta_driver_hardware_i2c)
+#include "driver/i2c.h"
+#elif defined(CONFIG_driver_softi2c)
+#include "driver/soft_i2c.h"
+#endif
+
+bool VEML6075::init()
+{
+	txbuf[0] = 0x00;
+	txbuf[1] = 0x00; // 50ms integration time, normal dynamic
+	if (i2c.xmit(address, 2, txbuf, 0, rxbuf) != 0) {
+		return false;
+	}
+	return true;
+}
+
+bool VEML6075::readUVCounts(float *uva, float *uvb)
+{
+	uint16_t uva_counts, uvb_counts, comp_visible, comp_ir;
+	txbuf[0] = 0x07;
+	if (i2c.xmit(address, 2, txbuf, 2, rxbuf) != 0) {
+		return false;
+	}
+	uva_counts = ((uint16_t)rxbuf[1] << 8) + rxbuf[0];
+
+	txbuf[0] = 0x09;
+	if (i2c.xmit(address, 2, txbuf, 2, rxbuf) != 0) {
+		return false;
+	}
+	uvb_counts = ((uint16_t)rxbuf[1] << 8) + rxbuf[0];
+
+	txbuf[0] = 0x0a;
+	if (i2c.xmit(address, 2, txbuf, 2, rxbuf) != 0) {
+		return false;
+	}
+	comp_visible = ((uint16_t)rxbuf[1] << 8) + rxbuf[0];
+
+	txbuf[0] = 0x0b;
+	if (i2c.xmit(address, 2, txbuf, 2, rxbuf) != 0) {
+		return false;
+	}
+	comp_ir = ((uint16_t)rxbuf[1] << 8) + rxbuf[0];
+
+	*uva = uva_counts - uva_a_coef * comp_visible - uva_b_coef * comp_ir;
+	*uvb = uvb_counts - uvb_c_coef * comp_visible - uvb_d_coef * comp_ir;
+
+	return true;
+}
+
+bool VEML6075::readUV(float *uva, float *uvb)
+{
+	float uva_counts, uvb_counts;
+	if (!readUVCounts(&uva_counts, &uvb_counts)) {
+		return false;
+	}
+
+	*uva = uva_counts * uva_counts_per_uwcm2;
+	*uvb = uvb_counts * uvb_counts_per_uwcm2;
+	return true;
+}
+
+bool VEML6075::readUVI(float *uva, float *uvb)
+{
+	float uva_counts, uvb_counts;
+	if (!readUVCounts(&uva_counts, &uvb_counts)) {
+		return false;
+	}
+
+	*uva = uva_counts * uva_uvi_response;
+	*uvb = uvb_counts * uvb_uvi_response;
+	return true;
+}
+
+VEML6075 veml6075(0x10);