add VEML6075 driver

1 files changed, 84 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