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Diffstat (limited to 'lib/bmp280.c')
| -rw-r--r-- | lib/bmp280.c | 185 |
1 files changed, 185 insertions, 0 deletions
diff --git a/lib/bmp280.c b/lib/bmp280.c new file mode 100644 index 0000000..89cf4cf --- /dev/null +++ b/lib/bmp280.c @@ -0,0 +1,185 @@ +/* + * spreadspace avr utils + * + * + * Copyright (C) 2016 Bernhard Tittelbach <bernhard@tittelbach.org> + * appreciative nod to Adafruit for writing a great example, go buy their stuff + * + * This file is part of spreadspace avr utils. + * + * spreadspace avr utils is free software: you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation, either version 3 of the License, or + * any later version. + * + * spreadspace avr utils is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with spreadspace avr utils. If not, see <http://www.gnu.org/licenses/>. + */ + +#include <stdio.h> +#include <avr/pgmspace.h> +#include <LUFA/Drivers/Peripheral/SPI.h> +#include "bmp280.h" + + +int32_t bmp280_t_fine = 0; + +void bmp280_cs(bmp280_sensor *sensor, uint8_t select) +{ + if (!select) + *(sensor->cs_port) |= _BV(sensor->cs_pin); + else + *(sensor->cs_port) &= ~ _BV(sensor->cs_pin); +} + +void bmp280_write8(uint8_t reg, uint8_t value) +{ + SPI_SendByte(reg & ~0x80); //bit 7 needs to be low for write mode + SPI_SendByte(value); +} + +uint8_t bmp280_read8(uint8_t reg) +{ + SPI_SendByte(reg | 0x80); //bit 7 high for read mode + return SPI_ReceiveByte(); +} + +uint16_t bmp280_read16(uint8_t reg) +{ + uint16_t value = 0; + SPI_SendByte(reg | 0x80); //bit 7 high for read mode + value |= ((uint16_t) SPI_ReceiveByte() & 0xFF) << 8; + value |= (uint16_t) SPI_ReceiveByte() & 0xFF; + return value; +} + +uint32_t bmp280_read24(uint8_t reg) +{ + uint32_t value = 0; + SPI_SendByte(reg | 0x80); //bit 7 high for read mode + value |= ((uint32_t) SPI_ReceiveByte() & 0xFF) << 16; + value |= ((uint32_t) SPI_ReceiveByte() & 0xFF) << 8; + value |= (uint32_t) SPI_ReceiveByte() & 0xFF; + return value; +} + +int16_t bmp280_readS16(uint8_t reg) +{ + return (int16_t) bmp280_read16(reg); +} + +uint16_t bmp280_read16_LE(uint8_t reg) +{ + uint16_t value = 0; + SPI_SendByte(reg | 0x80); //bit 7 high for read mode + value |= (uint16_t) SPI_ReceiveByte() & 0xFF; + value |= ((uint16_t) SPI_ReceiveByte() & 0xFF) << 8; + return value; +} + +int16_t bmp280_readS16_LE(uint8_t reg) +{ + return (int16_t)bmp280_read16_LE(reg); +} + +void bmp280_readCoefficients(bmp280_sensor *sensor) +{ + bmp280_cs(sensor, true); + sensor->dig_T1 = bmp280_read16_LE(BMP280_REGISTER_DIG_T1); + sensor->dig_T2 = bmp280_readS16_LE(BMP280_REGISTER_DIG_T2); + sensor->dig_T3 = bmp280_readS16_LE(BMP280_REGISTER_DIG_T3); + sensor->dig_P1 = bmp280_read16_LE(BMP280_REGISTER_DIG_P1); + sensor->dig_P2 = bmp280_readS16_LE(BMP280_REGISTER_DIG_P2); + sensor->dig_P3 = bmp280_readS16_LE(BMP280_REGISTER_DIG_P3); + sensor->dig_P4 = bmp280_readS16_LE(BMP280_REGISTER_DIG_P4); + sensor->dig_P5 = bmp280_readS16_LE(BMP280_REGISTER_DIG_P5); + sensor->dig_P6 = bmp280_readS16_LE(BMP280_REGISTER_DIG_P6); + sensor->dig_P7 = bmp280_readS16_LE(BMP280_REGISTER_DIG_P7); + sensor->dig_P8 = bmp280_readS16_LE(BMP280_REGISTER_DIG_P8); + sensor->dig_P9 = bmp280_readS16_LE(BMP280_REGISTER_DIG_P9); + bmp280_cs(sensor, false); +} + +//need to init SPI beforehand +void bmp280_init(bmp280_sensor *sensor, volatile uint8_t *cs_port, uint8_t cs_pin) +{ + memset(sensor,0,sizeof(bmp280_sensor)); + sensor->cs_port = cs_port; + sensor->cs_pin = cs_pin; + bmp280_readCoefficients(sensor); +} + +float bmp280_readTemp(bmp280_sensor *sensor) +{ + int32_t var1, var2; + + bmp280_cs(sensor, true); + int32_t adc_T = bmp280_read24(BMP280_REGISTER_TEMPDATA); + bmp280_cs(sensor, false); + adc_T >>= 4; + + var1 = ((((adc_T>>3) - ((int32_t)sensor->dig_T1 <<1))) * + ((int32_t)sensor->dig_T2)) >> 11; + + var2 = (((((adc_T>>4) - ((int32_t)sensor->dig_T1)) * + ((adc_T>>4) - ((int32_t)sensor->dig_T1))) >> 12) * + ((int32_t)sensor->dig_T3)) >> 14; + + bmp280_t_fine = var1 + var2; + + float T = (bmp280_t_fine * 5 + 128) >> 8; + return T/100; +} + +float bmp280_readPressure(bmp280_sensor *sensor) +{ + int64_t var1, var2, p; + + // Must be done first to get the bmp280_t_fine variable + bmp280_readTemp(sensor); + + bmp280_cs(sensor, true); + int32_t adc_P = bmp280_read24(BMP280_REGISTER_PRESSUREDATA); + bmp280_cs(sensor, false); + adc_P >>= 4; + + var1 = ((int64_t)bmp280_t_fine) - 128000; + var2 = var1 * var1 * (int64_t)sensor->dig_P6; + var2 = var2 + ((var1*(int64_t)sensor->dig_P5)<<17); + var2 = var2 + (((int64_t)sensor->dig_P4)<<35); + var1 = ((var1 * var1 * (int64_t)sensor->dig_P3)>>8) + + ((var1 * (int64_t)sensor->dig_P2)<<12); + var1 = (((((int64_t)1)<<47)+var1))*((int64_t)sensor->dig_P1)>>33; + + if (var1 == 0) + { + return 0; // avoid exception caused by division by zero + } + p = 1048576 - adc_P; + p = (((p<<31) - var2)*3125) / var1; + var1 = (((int64_t)sensor->dig_P9) * (p>>13) * (p>>13)) >> 25; + var2 = (((int64_t)sensor->dig_P8) * p) >> 19; + + p = ((p + var1 + var2) >> 8) + (((int64_t)sensor->dig_P7)<<4); + return (float)p/256; +} + +/*float bmp280_readAltitude(bmp280_sensor *sensor, float sealevelp) +{ + float altitude; + + float pressure = bmp280_readPressure(sensor); // in Si units for Pascal + pressure /= 100; + + altitude = 44330 * (1.0 - pow(pressure / seaLevelhPa, 0.1903)); + + return altitude; +}*/ + + +/// Helper Functions |