- small corrections
- changes to use the same source code with ESP8266 (esp-open-rtos) and ESP32 (ESP-IDF)
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Gunar Schorcht
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9 changed files with 251 additions and 138 deletions
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@ -1,6 +1,8 @@
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# Driver for the ams CCS811 digital gas sensor for monitoring indoor air quality.
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This driver is written for usage with the ESP8266 and FreeRTOS using the I2C interface driver.
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The driver is for the usage with the ESP8266 and [esp-open-rtos](https://github.com/SuperHouse/esp-open-rtos).
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It is also working with ESP32 and [ESP-IDF](https://github.com/espressif/esp-idf.git) using a wrapper component for ESP8266 functions, see folder ```components/esp8266_wrapper```, as well as Linux based systems using a wrapper library.
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## About the sensor
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@ -32,7 +34,7 @@ After power up, the sensor starts automatically in *Idle, Low Current Mode* (```
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**Please note:** In *Constant Power Mode* with measurements every 250 ms (```mode_250ms```) only raw data are available. In all other measurement modes, the Indoor Air Quality (IAQ) values are available additionally. The *Constant Power Mode* with measurements every 250 ms (```mode_250ms```) is only intended for systems where an external host system wants to run an algorithm with raw data.
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Once the is initialized with function ```ccs811_init_sensor```, function ```ccs811_set_mode``` can be used to start periodic measurements with a given period.
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Once the sensor is initialized with function ```ccs811_init_sensor```, function ```ccs811_set_mode``` can be used to start periodic measurements with a given period.
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```
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static ccs811_sensor_t* sensor;
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@ -211,42 +213,46 @@ First, the hardware configuration has to be established.
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### Hardware configurations
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Following figure shows the hardware configuration if no interrupt is used.
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Following figure shows the hardware configuration for ESP8266 and ESP32 if no interrupt is used.
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```
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+------------------------+ +--------+
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| ESP8266 Bus 0 | | CCS811 |
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| GPIO 5 (SCL) >----> SCL |
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| GPIO 4 (SDA) ------ SDA |
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| GND -----> /WAKE |
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+------------------------+ +--------+
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+------------------+ +--------+
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| ESP8266 / ESP32 | | CCS811 |
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| | | |
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| GPIO 14 (SCL) >-------> SCL |
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| GPIO 13 (SDA) <-------> SDA |
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| GND --------> /WAKE |
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+------------------+ +--------+
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```
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If interrupt signal *nINT* is used to fetch new data, additionally the interrupt pin has to be connected to a GPIO pin.
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```
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+------------------------+ +--------+
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| ESP8266 Bus 0 | | CCS811 |
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| GPIO 5 (SCL) >----> SCL |
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| GPIO 4 (SDA) ------ SDA |
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| GPIO 2 <----- /nINT |
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| GND -----> /WAKE |
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+------------------------+ +--------+
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+------------------+ +--------+
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| ESP8266 / ESP32 | | CCS811 |
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| | | |
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| GPIO 14 (SCL) >-------> SCL |
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| GPIO 13 (SDA) <-------> SDA |
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| GPIO 5 <-------- /nINT |
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| GND --------> /WAKE |
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+------------------+ +--------+
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```
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If CCS811 sensor is used in conjunction with another sensor, e.g., a SHT3x sensor, the hardware configuration looks like following:
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```
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+------------------------+ +--------+
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| ESP8266 Bus 0 | | CCS811 |
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| GPIO 5 (SCL) >--+----> SCL |
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| GPIO 4 (SDA) ---|-+--- SDA |
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| GND ---|-|--> /WAKE |
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| | | | +--------+
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| | | | | SHT3x |
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| | +----> SCL |
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| | +--- SDA |
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+------------------------+ +--------+
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+------------------+ +--------+
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| ESP8266 / ESP32 | | CCS811 |
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| | | |
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| GPIO 14 (SCL) >--+----> SCL |
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| GPIO 13 (SDA) <--|-+--> SDA |
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| GND ---|-|--> /WAKE |
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| | | | +--------+
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| | | | | SHT3x |
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| | | | | |
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| | +----> SCL |
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| | +--> SDA |
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+------------------+ +--------+
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```
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### Communication interface settings
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@ -256,12 +262,11 @@ Dependent on the hardware configuration, the communication interface settings ha
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```
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// define I2C interfaces at which CCS811 sensors can be connected
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#define I2C_BUS 0
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#define I2C_SCL_PIN 5
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#define I2C_SDA_PIN 4
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#define I2C_SCL_PIN 14
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#define I2C_SDA_PIN 13
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// define GPIO for interrupt
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#define INT_GPIO 2
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#include "sht3x/sht3x.h"
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#define INT_GPIO 5
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```
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### Main program
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@ -272,7 +277,7 @@ Before using the CCS811 driver, function ```i2c_init``` needs to be called for e
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```
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...
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i2c_init(I2C_BUS, I2C_SCL_PIN, I2C_SDA_PIN, I2C_FREQ_100K));
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i2c_init(I2C_BUS, I2C_SCL_PIN, I2C_SDA_PIN, I2C_FREQ_100K);
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i2c_set_clock_stretch (I2C_BUS, CCS811_I2C_CLOCK_STRETCH);
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...
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```
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@ -401,31 +406,47 @@ ccs811_set_eco2_thresholds (sensor, 600, 1100, 40);
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## Full Example
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```
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// use following constants to define the demo mode
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/* -- use following constants to define the example mode ----------- */
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// #define INT_DATA_RDY_USED
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// #define INT_THRESHOLD_USED
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#include "espressif/esp_common.h"
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#include "esp/uart.h"
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#include "i2c/i2c.h"
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#if defined(INT_DATA_RDY_USED) || defined(INT_THRESHOLD_USED)
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#define INT_USED
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#endif
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#include "FreeRTOS.h"
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#include <task.h>
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/* -- includes ----------------------------------------------------- */
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// include CCS811 driver
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#include "ccs811/ccs811.h"
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#include "ccs811.h"
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// define I2C interfaces at which CCS811 sensors can be connected
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/* -- platform dependent definitions ------------------------------- */
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#ifdef ESP_PLATFORM // ESP32 (ESP-IDF)
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// user task stack depth for ESP32
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#define TASK_STACK_DEPTH 2048
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#else // ESP8266 (esp-open-rtos)
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// user task stack depth for ESP8266
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#define TASK_STACK_DEPTH 256
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#endif // ESP_PLATFORM
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// I2C interface defintions for ESP32 and ESP8266
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#define I2C_BUS 0
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#define I2C_SCL_PIN 5
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#define I2C_SDA_PIN 4
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#define I2C_SCL_PIN 14
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#define I2C_SDA_PIN 13
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#define I2C_FREQ I2C_FREQ_100K
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// define GPIO for interrupt
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#define INT_GPIO 2
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// interrupt GPIOs defintions for ESP8266 and ESP32
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#define nINT_PIN 13
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/* -- user tasks --------------------------------------------------- */
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static ccs811_sensor_t* sensor;
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#if defined(INT_DATA_RDY_USED) || defined(INT_THRESHOLD_USED)
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#ifdef INT_USED
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/**
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* In this example, the interrupt *nINT* is used. It is triggered every time
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* new data are available (INT_DATA_RDY_USED) or exceed defined thresholds
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@ -459,12 +480,12 @@ void user_task_interrupt (void *pvParameters)
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// Interrupt handler which resumes user_task_interrupt on interrupt
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void nINT_handler (uint8_t gpio)
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static void IRAM nINT_handler(uint8_t gpio)
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{
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xTaskResumeFromISR (nINT_task);
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}
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#else
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#else // !INT_USED
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/*
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* In this example, user task fetches the sensor values every seconds.
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@ -492,21 +513,22 @@ void user_task_periodic(void *pvParameters)
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}
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}
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#endif
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#endif // INT_USED
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/* -- main program ------------------------------------------------- */
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void user_init(void)
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{
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// set UART Parameter
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// Set UART Parameter.
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uart_set_baud(0, 115200);
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// give the UART some time to settle
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sdk_os_delay_us(500);
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// Give the UART some time to settle
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vTaskDelay(1);
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/** -- MANDATORY PART -- */
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// init all I2C bus interfaces at which CCS811 sensors are connected
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i2c_init(I2C_BUS, I2C_SCL_PIN, I2C_SDA_PIN, I2C_FREQ_100K);
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i2c_init (I2C_BUS, I2C_SCL_PIN, I2C_SDA_PIN, I2C_FREQ);
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// longer clock stretching is required for CCS811
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i2c_set_clock_stretch (I2C_BUS, CCS811_I2C_CLOCK_STRETCH);
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@ -515,33 +537,35 @@ void user_init(void)
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if (sensor)
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{
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#if defined(INT_DATA_RDY_USED) || defined(INT_THRESHOLD_USED)
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#if !defined (INT_USED)
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// create a periodic task that uses the sensor
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xTaskCreate(user_task_periodic, "user_task_periodic", TASK_STACK_DEPTH, NULL, 2, NULL);
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#else // INT_USED
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// create a task that is resumed by interrupt handler to use the sensor
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xTaskCreate(user_task_interrupt, "user_task_interrupt", 256, NULL, 2, &nINT_task);
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xTaskCreate(user_task_interrupt, "user_task_interrupt", TASK_STACK_DEPTH, NULL, 2, &nINT_task);
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// activate the interrupt for INT_GPIO and set the interrupt handler
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gpio_set_interrupt(INT_GPIO, GPIO_INTTYPE_EDGE_NEG, nINT_handler);
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// activate the interrupt for nINT_PIN and set the interrupt handler
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gpio_enable(nINT_PIN, GPIO_INPUT);
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gpio_set_interrupt(nINT_PIN, GPIO_INTTYPE_EDGE_NEG, nINT_handler);
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#ifdef INT_DATA_RDY_USED
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// enable the data ready interrupt
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ccs811_enable_interrupt (sensor, true);
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#else
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#else // INT_THRESHOLD_USED
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// set threshold parameters and enable threshold interrupt mode
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ccs811_set_eco2_thresholds (sensor, 600, 1100, 40);
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#endif
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#else
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// create a periodic task that uses the sensor
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xTaskCreate(user_task_periodic, "user_task_periodic", 256, NULL, 2, NULL);
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#endif
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#endif // !defined(INT_USED)
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// start periodic measurement with one measurement per second
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ccs811_set_mode (sensor, ccs811_mode_1s);
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}
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}
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```
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## Further Examples
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