From 67e9d173ca0b504305a3fd3d8d1ad7b64e2d23dd Mon Sep 17 00:00:00 2001 From: Joey Castillo Date: Wed, 4 Aug 2021 18:35:58 -0400 Subject: new project: sensor watch environment --- Sensor Watch BME280 Project/app.c | 184 ++++++++++++++++++++++++++++++++++++++ 1 file changed, 184 insertions(+) create mode 100644 Sensor Watch BME280 Project/app.c (limited to 'Sensor Watch BME280 Project/app.c') diff --git a/Sensor Watch BME280 Project/app.c b/Sensor Watch BME280 Project/app.c new file mode 100644 index 00000000..f2605070 --- /dev/null +++ b/Sensor Watch BME280 Project/app.c @@ -0,0 +1,184 @@ +#include +#include +#include "watch.h" +#include "app.h" +#include "bme280.h" + +typedef enum ApplicationMode { + MODE_TEMPERATURE = 0, + MODE_HUMIDITY, + MODE_OFF, +} ApplicationMode; + +typedef struct ApplicationState { + ApplicationMode mode; + bool light_on; + uint16_t dig_T1; + int16_t dig_T2; + int16_t dig_T3; + uint8_t dig_H1; + int16_t dig_H2; + uint8_t dig_H3; + int16_t dig_H4; + int16_t dig_H5; + int8_t dig_H6; +} ApplicationState; + +ApplicationState application_state; + + +void cb_mode_pressed(); +void cb_tick(); + +float read_temperature(int32_t *p_t_fine); +float read_humidity(int32_t t_fine); + +/** + * @brief Zeroes out the application state struct. + */ +void app_init() { + memset(&application_state, 0, sizeof(application_state)); +} + +/** + * @todo stash the BME280's calibration values in backup memory so we don't have to ask again + */ +void app_wake_from_deep_sleep() { +} + +/** + * Enables the MODE button, the display and the sensor, and grabs calibration data. + */ +void app_setup() { + watch_enable_buttons(); + watch_register_button_callback(BTN_MODE, cb_mode_pressed); + + // pin A0 powers the sensor on this board. + watch_enable_digital_output(A0); + watch_set_pin_level(A0, true); + delay_ms(10); + + watch_enable_i2c(); + + watch_i2c_write8(BME280_ADDRESS, BME280_REGISTER_SOFTRESET, BME280_SOFT_RESET_CODE); + delay_ms(10); + application_state.dig_T1 = watch_i2c_read16(BME280_ADDRESS, BME280_REGISTER_DIG_T1); + application_state.dig_T2 = (int16_t)watch_i2c_read16(BME280_ADDRESS, BME280_REGISTER_DIG_T2); + application_state.dig_T3 = (int16_t)watch_i2c_read16(BME280_ADDRESS, BME280_REGISTER_DIG_T3); + application_state.dig_H1 = watch_i2c_read8(BME280_ADDRESS, BME280_REGISTER_DIG_H1); + application_state.dig_H2 = (int16_t)watch_i2c_read16(BME280_ADDRESS, BME280_REGISTER_DIG_H2); + application_state.dig_H3 = watch_i2c_read8(BME280_ADDRESS, BME280_REGISTER_DIG_H3); + application_state.dig_H4 = ((int8_t)watch_i2c_read8(BME280_ADDRESS, BME280_REGISTER_DIG_H4) << 4) | + (watch_i2c_read8(BME280_ADDRESS, BME280_REGISTER_DIG_H4 + 1) & 0xF); + application_state.dig_H5 = ((int8_t)watch_i2c_read8(BME280_ADDRESS, BME280_REGISTER_DIG_H5 + 1) << 4) | + (watch_i2c_read8(BME280_ADDRESS, BME280_REGISTER_DIG_H5) >> 4); + application_state.dig_H6 = (int8_t)watch_i2c_read8(BME280_ADDRESS, BME280_REGISTER_DIG_H6); + + watch_i2c_write8(BME280_ADDRESS, BME280_REGISTER_CONTROL_HUMID, BME280_CONTROL_HUMID_SAMPLING_X16); + watch_i2c_write8(BME280_ADDRESS, BME280_REGISTER_CONTROL, BME280_CONTROL_TEMPERATURE_SAMPLING_X16 | + BME280_CONTROL_PRESSURE_SAMPLING_NONE | + BME280_CONTROL_MODE_NORMAL); + + watch_enable_display(); + + watch_register_tick_callback(cb_tick); +} + +/** + * Nothing to do here. + */ +void app_prepare_for_sleep() { +} + +/** + * @todo restore the BME280's calibration values from backup memory + */ +void app_wake_from_sleep() { +} + +/** + * Displays the temperature and humidity on screen, or a string indicating no measurements are being taken. + */ +bool app_loop() { + int32_t t_fine; + float temperature; + float humidity; + char buf[11] = {0}; + + switch (application_state.mode) { + case MODE_TEMPERATURE: + temperature = read_temperature(NULL); + sprintf(buf, "TE %4.1f#C", temperature); + watch_display_string(buf, 0); + watch_clear_pixel(1, 16); + break; + case MODE_HUMIDITY: + temperature = read_temperature(&t_fine); + humidity = read_humidity(t_fine); + sprintf(buf, "HU rH %3d", (int)humidity); + watch_display_string(buf, 0); + watch_set_pixel(1, 16); + break; + case MODE_OFF: + watch_display_string(" Sleep ", 0); + watch_clear_pixel(1, 16); + } + + return true; +} + +/** + * Reads the temperature from the BME280 + * @param p_t_fine - an optional pointer to an int32_t; if provided, the t_fine measurement + * (required for humidity calculation) will be returned by reference. + * Pass in NULL if you do not care about this value. + * @return a float indicating the temperature in degrees celsius. + */ +float read_temperature(int32_t *p_t_fine) { + // read24 reads the bytes into a uint32 which works for little-endian values (MSB is 0) + uint32_t raw_data = watch_i2c_read24(BME280_ADDRESS, BME280_REGISTER_TEMP_DATA) >> 8; + // alas the sensor's register layout is big-endian-ish, with a nibble of zeroes at the end of the LSB. + // this line shuffles everything back into place (swaps LSB and MSB and shifts the zeroes off the end) + int32_t adc_value = (((raw_data >> 16) | (raw_data & 0xFF00) | (raw_data << 16)) & 0xFFFFFF) >> 4; + + // this bit is cribbed from Adafruit's BME280 driver. support their open source efforts by buying some stuff! + int32_t var1 = ((((adc_value >> 3) - ((int32_t)application_state.dig_T1 << 1))) * ((int32_t)application_state.dig_T2)) >> 11; + int32_t var2 = (((((adc_value >> 4) - ((int32_t)application_state.dig_T1)) * ((adc_value >> 4) - ((int32_t)application_state.dig_T1))) >> 12) * ((int32_t)application_state.dig_T3)) >> 14; + int32_t t_fine = var1 + var2; + + // if we got a pointer to a t_fine, return it by reference (for humidity calculation). + if (p_t_fine != NULL) *p_t_fine = t_fine; + + return ((t_fine * 5 + 128) >> 8) / 100.0; +} + +/** + * Reads the humidity from the BME280 + * @param t_fine - the t_fine measurement from a call to read_temperature + * @return a float indicating the temperature in degrees celsius. + */ +float read_humidity(int32_t t_fine) { + int32_t adc_value = watch_i2c_read16(BME280_ADDRESS, BME280_REGISTER_HUMID_DATA); + // the sensor returns this as big-endian, so swap the bytes. + adc_value = (adc_value >> 8) | (adc_value << 8); + + // again, cribbed from Adafruit's BME280 driver. they sell a great breakout board for this sensor! + int32_t v_x1_u32r = v_x1_u32r = (t_fine - ((int32_t)76800)); + v_x1_u32r = (((((adc_value << 14) - (((int32_t)application_state.dig_H4) << 20) - (((int32_t)application_state.dig_H5) * v_x1_u32r)) + + ((int32_t)16384)) >> 15) * (((((((v_x1_u32r * ((int32_t)application_state.dig_H6)) >> 10) * (((v_x1_u32r * ((int32_t)application_state.dig_H3)) >> 11) + + ((int32_t)32768))) >> 10) + ((int32_t)2097152)) * ((int32_t)application_state.dig_H2) + 8192) >> 14)); + v_x1_u32r = (v_x1_u32r - (((((v_x1_u32r >> 15) * (v_x1_u32r >> 15)) >> 7) * ((int32_t)application_state.dig_H1)) >> 4)); + v_x1_u32r = (v_x1_u32r < 0) ? 0 : v_x1_u32r; + v_x1_u32r = (v_x1_u32r > 419430400) ? 419430400 : v_x1_u32r; + float h = (v_x1_u32r >> 12); + + return h / 1024.0; +} + +void cb_mode_pressed() { + application_state.mode = (application_state.mode + 1) % 3; +} + +void cb_tick() { +} + -- cgit v1.2.3