Add Sensirion SEN66 driver

5 files changed, 285 insertions, 0 deletions

diff --git a/Makefile b/Makefile
index d49d5d5..a5fde65 100644
--- a/Makefile
+++ b/Makefile
@@ -122,6 +122,10 @@ ifdef CONFIG_driver_sen5x
 	CXX_TARGETS += src/driver/sen5x.cc
 endif
 
+ifdef CONFIG_driver_sen66
+	CXX_TARGETS += src/driver/sen66.cc
+endif
+
 ifdef CONFIG_driver_veml6075
 	CXX_TARGETS += src/driver/veml6075.cc
 endif
diff --git a/include/driver/sen66.h b/include/driver/sen66.h
new file mode 100644
index 0000000..117c32b
--- /dev/null
+++ b/include/driver/sen66.h
@@ -0,0 +1,102 @@
+/*
+ * Copyright 2025 Birte Kristina Friesel
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+#ifndef SEN66_H
+#define SEN66_H
+
+class SEN66 {
+	private:
+		SEN66(const SEN66 &copy);
+		unsigned char const address = 0x6b;
+		unsigned char txbuf[2];
+		unsigned char rxbuf[27];
+
+		unsigned char crcWord(unsigned char byte1, unsigned char byte2);
+		bool crcValid(unsigned char* data, unsigned char length);
+
+	public:
+		SEN66() {}
+
+		unsigned short const PM_INVALID = 0xffff;
+		signed short const TEMPERATURE_INVALID = 0x7fff;
+		signed short const HUMIDITY_INVALID = 0x7fff;
+		signed short const VOC_INVALID = 0x7fff;
+		signed short const NOX_INVALID = 0x7fff;
+		signed short const CO2_INVALID = 0xffff;
+
+		struct {
+			unsigned int fan_speed_warning : 1;
+			unsigned int gas_sensor_error : 1;
+			unsigned int rht_sensor_error : 1;
+			unsigned int co2_sensor_error : 1;
+			unsigned int pm_sensor_error : 1;
+			unsigned int fan_error : 1;
+		};
+
+		/*
+		 * PM1.0 value, scaled by 10.
+		 * PM1.0 [µg/m³] = pm10 / 10
+		 */
+		unsigned short pm1;
+
+		/*
+		 * PM2.5 value, scaled by 10.
+		 * PM2.5 [µg/m3] = pm2_5 / 10
+		 */
+		unsigned short pm2_5;
+
+		/*
+		 * PM4.0 value, scaled by 10.
+		 * PM4.0 [µg/m3] = pm4 / 10
+		 */
+		unsigned short pm4;
+
+		/*
+		 * PM10 value, scaled by 10.
+		 * PM10 [µg/m3] = pm10 / 10
+		 */
+		unsigned short pm10;
+
+		/*
+		 * Temperature, scaled by 200.
+		 * Temperature [°c] = temperature / 200
+		 */
+		signed short temperature;
+
+		/*
+		 * Relative Humidity, scaled by 100.
+		 * Relative Humidity [%] = humidity / 100
+		 */
+		signed short humidity;
+
+		/*
+		 * VOC Index, scaled by 10.
+		 * VOC index = voc / 10
+		 */
+		signed short voc;
+
+		/*
+		 * NOx Index, scaled by 10.
+		 * NOx index = nox / 10
+		 */
+		signed short nox;
+
+		/*
+		 * CO₂ concentration [ppm].
+		 */
+		unsigned short co2;
+
+		void start();
+		void stop();
+
+		void cleanFan();
+
+		bool read();
+		bool readStatus();
+};
+
+extern SEN66 sen66;
+
+#endif
diff --git a/src/app/datalogger/main.cc b/src/app/datalogger/main.cc
index de0a782..d2cfdba 100644
--- a/src/app/datalogger/main.cc
+++ b/src/app/datalogger/main.cc
@@ -60,6 +60,9 @@
 #ifdef CONFIG_driver_sen5x
 #include "driver/sen5x.h"
 #endif
+#ifdef CONFIG_driver_sen66
+#include "driver/sen66.h"
+#endif
 #ifdef CONFIG_driver_veml6075
 #include "driver/veml6075.h"
 #endif
@@ -266,6 +269,61 @@ void loop(void)
 	}
 #endif
 
+#ifdef CONFIG_driver_sen66
+	if (sen66.read()) {
+		kout << dec;
+		if (sen66.co2 != sen66.CO2_INVALID) {
+			kout << "CO₂  : " << sen66.co2 << " ppm" << endl;
+		}
+		if (sen66.pm1 != sen66.PM_INVALID) {
+			kout << "PM1.0: " << (sen66.pm1 / 10) << "." << (sen66.pm1 % 10) << " µg/m³" << endl;
+		}
+		if (sen66.pm2_5 != sen66.PM_INVALID) {
+			kout << "PM2.5: " << (sen66.pm2_5 / 10) << "." << (sen66.pm2_5 % 10) << " µg/m³" << endl;
+		}
+		if (sen66.pm4 != sen66.PM_INVALID) {
+			kout << "PM4.0: " << (sen66.pm4 / 10) << "." << (sen66.pm4 % 10) << " µg/m³" << endl;
+		}
+		if (sen66.pm10 != sen66.PM_INVALID) {
+			kout << "PM10 : " << (sen66.pm10 / 10) << "." << (sen66.pm10 % 10) << " µg/m³" << endl;
+		}
+		if (sen66.humidity != sen66.HUMIDITY_INVALID) {
+			kout << "Humidity: " << (sen66.humidity / 100) << "." << ((sen66.humidity % 100) / 10) << " %" << endl;
+		}
+		if (sen66.temperature != sen66.TEMPERATURE_INVALID) {
+			kout << "Temperature: " << (sen66.temperature / 200) << "." << ((sen66.temperature % 200) / 20) << " °c" << endl;
+		}
+		if (sen66.voc != sen66.VOC_INVALID) {
+			kout << "VOC index: " << (sen66.voc / 10) << "." << (sen66.voc % 10) << endl;
+		}
+		if (sen66.nox != sen66.NOX_INVALID) {
+			kout << "NOx index: " << (sen66.nox / 10) << "." << (sen66.nox % 10) << endl;
+		}
+	} else {
+		kout << "SEN66 error" << endl;
+	}
+	if (sen66.readStatus()) {
+		if (sen66.fan_speed_warning) {
+			kout << "SEN66 warning: fan speed out of range" << endl;
+		}
+		if (sen66.co2_sensor_error) {
+			kout << "SEN66 error: CO₂ sensor" << endl;
+		}
+		if (sen66.gas_sensor_error) {
+			kout << "SEN66 error: Gas (VOC, NOx) sensor" << endl;
+		}
+		if (sen66.rht_sensor_error) {
+			kout << "SEN66 error: Temperature and Humidity sensor" << endl;
+		}
+		if (sen66.pm_sensor_error) {
+			kout << "SEN66 error: PM sensor" << endl;
+		}
+		if (sen66.fan_error) {
+			kout << "SEN66 error: Fan" << endl;
+		}
+	}
+#endif
+
 #ifdef CONFIG_driver_veml6075
 	float uva, uvb;
 	if (veml6075.readUV(&uva, &uvb)) {
@@ -392,6 +450,10 @@ int main(void)
 	sen5x.start();
 #endif
 
+#ifdef CONFIG_driver_sen66
+	sen66.start();
+#endif
+
 #ifdef CONFIG_driver_veml6075
 	veml6075.init();
 #endif
diff --git a/src/driver/Kconfig b/src/driver/Kconfig
index 4639698..86b1a5d 100644
--- a/src/driver/Kconfig
+++ b/src/driver/Kconfig
@@ -145,6 +145,10 @@ config driver_sen5x
 bool "Sensirion SEN5x PM Sensor"
 depends on meta_driver_i2c
 
+config driver_sen66
+bool "Sensirion SEN66 PM+CO2 Sensor"
+depends on meta_driver_i2c
+
 config driver_veml6075
 bool "VEML6075 UV Sensor"
 depends on meta_driver_i2c
diff --git a/src/driver/sen66.cc b/src/driver/sen66.cc
new file mode 100644
index 0000000..6b12e67
--- /dev/null
+++ b/src/driver/sen66.cc
@@ -0,0 +1,113 @@
+/*
+ * Copyright 2025 Birte Kristina Friesel
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+#include "arch.h"
+#include "driver/sen66.h"
+#if defined(CONFIG_meta_driver_hardware_i2c)
+#include "driver/i2c.h"
+#elif defined(CONFIG_driver_softi2c)
+#include "driver/soft_i2c.h"
+#endif
+
+void SEN66::cleanFan()
+{
+	txbuf[0] = 0x56;
+	txbuf[1] = 0x07;
+	i2c.xmit(address, 2, txbuf, 0, rxbuf);
+}
+
+void SEN66::start()
+{
+	txbuf[0] = 0x00;
+	txbuf[1] = 0x21;
+	i2c.xmit(address, 2, txbuf, 0, rxbuf);
+}
+
+void SEN66::stop()
+{
+	txbuf[0] = 0x01;
+	txbuf[1] = 0x04;
+	i2c.xmit(address, 2, txbuf, 0, rxbuf);
+}
+
+bool SEN66::read()
+{
+	txbuf[0] = 0x03;
+	txbuf[1] = 0x00;
+
+	if (i2c.xmit(address, 2, txbuf, 0, rxbuf)) {
+		return false;
+	}
+	arch.delay_ms(20);
+	if (i2c.xmit(address, 0, txbuf, 27, rxbuf)) {
+		return false;
+	}
+
+	if (!crcValid(rxbuf, 27)) {
+		return false;
+	}
+
+	pm1 = (rxbuf[0] << 8) + rxbuf[1];
+	pm2_5 = (rxbuf[3] << 8) + rxbuf[4];
+	pm4 = (rxbuf[6] << 8) + rxbuf[7];
+	pm10 = (rxbuf[9] << 8) + rxbuf[10];
+	humidity = (rxbuf[12] << 8) + rxbuf[13];
+	temperature = (rxbuf[15] << 8) + rxbuf[16];
+	voc = (rxbuf[18] << 8) + rxbuf[19];
+	nox = (rxbuf[21] << 8) + rxbuf[22];
+	co2 = (rxbuf[24] << 8) + rxbuf[25];
+	return true;
+}
+
+bool SEN66::readStatus()
+{
+	txbuf[0] = 0xd2;
+	txbuf[1] = 0x06;
+	if (i2c.xmit(address, 2, txbuf, 0, rxbuf)) {
+		return false;
+	}
+	arch.delay_ms(20);
+	if (i2c.xmit(address, 0, txbuf, 6, rxbuf)) {
+		return false;
+	}
+
+	if (!crcValid(rxbuf, 6)) {
+		return false;
+	}
+
+	fan_speed_warning = rxbuf[1] & 0x20;
+	co2_sensor_error = rxbuf[3] & 0x12;
+	pm_sensor_error = rxbuf[3] & 0x08;
+	gas_sensor_error = rxbuf[4] & 0x80;
+	rht_sensor_error = rxbuf[4] & 0x40;
+	fan_error = rxbuf[4] & 0x10;
+
+	return true;
+}
+
+unsigned char SEN66::crcWord(unsigned char byte1, unsigned char byte2)
+{
+	unsigned char crc = 0xff ^ byte1;
+	for (unsigned char bit = 8; bit > 0; bit--) {
+		crc = (crc << 1) ^ (crc & 0x80 ? 0x31 : 0);
+	}
+	crc ^= byte2;
+	for (unsigned char bit = 8; bit > 0; bit--) {
+		crc = (crc << 1) ^ (crc & 0x80 ? 0x31 : 0);
+	}
+	return crc;
+}
+
+bool SEN66::crcValid(unsigned char* data, unsigned char length)
+{
+	for (unsigned char i = 0; i < length; i += 3) {
+		if (crcWord(data[i], data[i+1]) != data[i+2]) {
+			return false;
+		}
+	}
+	return true;
+}
+
+SEN66 sen66;