Naresh Krish
/
itracker-mbed-os-example-bme280
Sample program on how to use the LIS2MDL sensor on the RAKWirelss iTracker module
Diff: BME280_SPI/BME280_SPI.cpp
- Revision:
- 0:a8bfd25ff975
--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/BME280_SPI/BME280_SPI.cpp Mon Feb 12 05:04:29 2018 +0000 @@ -0,0 +1,226 @@ +/** + ****************************************************************************** + * @file BME280_SPI.cpp + * @author Toyomasa Watarai + * @version V1.0.0 + * @date 11 March 2017 + * @brief BME280_SPI class implementation + ****************************************************************************** + * @attention + * + * Licensed under the Apache License, Version 2.0 (the "License"); + * you may not use this file except in compliance with the License. + * You may obtain a copy of the License at + * + * http://www.apache.org/licenses/LICENSE-2.0 + * + * Unless required by applicable law or agreed to in writing, software + * distributed under the License is distributed on an "AS IS" BASIS, + * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. + * See the License for the specific language governing permissions and + * limitations under the License. + */ + +#include "mbed.h" +#include "BME280_SPI.h" +#include "SEGGER_RTT.h" + +BME280_SPI::BME280_SPI(PinName mosi, PinName miso, PinName sclk, PinName cs) + : + _spi(mosi, miso, sclk), + _cs(cs), + t_fine(0) +{ + initialize(); +} + + +BME280_SPI::~BME280_SPI() +{ +} + +void BME280_SPI::initialize() +{ + char cmd[18]; + + _cs = 1; + _spi.format(8, 0); // 8-bit, mode=0 + _spi.frequency(1000000); // 1MHZ + + _cs = 0; + _spi.write(0xd0); // chip_id + cmd[0] = _spi.write(0); // read chip_id + _cs = 1; + + DEBUG_PRINT("chip_id = 0x%x\n", cmd[0]); + + _cs = 0; + _spi.write(0xf2 & BME280_SPI_MASK); // ctrl_hum + _spi.write(0x04); // Humidity oversampling x4 + _cs = 1; + + _cs = 0; + _spi.write(0xf4 & BME280_SPI_MASK); // ctrl_meas + _spi.write((4<<5)|(4<<2)|3); // Temparature oversampling x4, Pressure oversampling x4, Normal mode + _cs = 1; + + _cs = 0; + _spi.write(0xf5 & BME280_SPI_MASK); // config + _spi.write(0xa0); // Standby 1000ms, Filter off, 4-wire SPI interface + _cs = 1; + + wait(1); + + _cs = 0; + _spi.write(0x88); // read dig_T regs + for(int i = 0; i < 6; i++) + cmd[i] = _spi.write(0); + _cs = 1; + + dig_T1 = (cmd[1] << 8) | cmd[0]; + dig_T2 = (cmd[3] << 8) | cmd[2]; + dig_T3 = (cmd[5] << 8) | cmd[4]; + + DEBUG_PRINT("dig_T = 0x%x, 0x%x, 0x%x\n", dig_T1, dig_T2, dig_T3); + DEBUG_PRINT("dig_T = %d, %d, %d\n", dig_T1, dig_T2, dig_T3); + + _cs = 0; + _spi.write(0x8e); // read dig_P regs + for(int i = 0; i < 18; i++) + cmd[i] = _spi.write(0); + _cs = 1; + + dig_P1 = (cmd[ 1] << 8) | cmd[ 0]; + dig_P2 = (cmd[ 3] << 8) | cmd[ 2]; + dig_P3 = (cmd[ 5] << 8) | cmd[ 4]; + dig_P4 = (cmd[ 7] << 8) | cmd[ 6]; + dig_P5 = (cmd[ 9] << 8) | cmd[ 8]; + dig_P6 = (cmd[11] << 8) | cmd[10]; + dig_P7 = (cmd[13] << 8) | cmd[12]; + dig_P8 = (cmd[15] << 8) | cmd[14]; + dig_P9 = (cmd[17] << 8) | cmd[16]; + + DEBUG_PRINT("dig_P = 0x%x, 0x%x, 0x%x, 0x%x, 0x%x, 0x%x, 0x%x, 0x%x, 0x%x\n", dig_P1, dig_P2, dig_P3, dig_P4, dig_P5, dig_P6, dig_P7, dig_P8, dig_P9); + DEBUG_PRINT("dig_P = %d, %d, %d, %d, %d, %d, %d, %d, %d\n", dig_P1, dig_P2, dig_P3, dig_P4, dig_P5, dig_P6, dig_P7, dig_P8, dig_P9); + + _cs = 0; + _spi.write(0xA1); // read dig_H1 reg + cmd[0] = _spi.write(0); + _cs = 1; + + _cs = 0; + _spi.write(0xE1); // read dig_H regs + for(int i = 0; i < 7; i++) + cmd[1+i] = _spi.write(0); + _cs = 1; + + dig_H1 = cmd[0]; + dig_H2 = (cmd[2] << 8) | cmd[1]; + dig_H3 = cmd[3]; + dig_H4 = (cmd[4] << 4) | (cmd[5] & 0x0f); + dig_H5 = (cmd[6] << 4) | ((cmd[5]>>4) & 0x0f); + dig_H6 = cmd[7]; + + DEBUG_PRINT("dig_H = 0x%x, 0x%x, 0x%x, 0x%x, 0x%x, 0x%x\n", dig_H1, dig_H2, dig_H3, dig_H4, dig_H5, dig_H6); + DEBUG_PRINT("dig_H = %d, %d, %d, %d, %d, %d\n", dig_H1, dig_H2, dig_H3, dig_H4, dig_H5, dig_H6); +} + +float BME280_SPI::getTemperature() +{ + uint32_t temp_raw; + float tempf; + char cmd[3]; + + _cs = 0; + _spi.write(0xfa); + for(int i = 0; i < 3; i++) + cmd[i] = _spi.write(0); + _cs = 1; + + temp_raw = (cmd[0] << 12) | (cmd[1] << 4) | (cmd[2] >> 4); + + int32_t temp; + + temp = + (((((temp_raw >> 3) - (dig_T1 << 1))) * dig_T2) >> 11) + + ((((((temp_raw >> 4) - dig_T1) * ((temp_raw >> 4) - dig_T1)) >> 12) * dig_T3) >> 14); + + t_fine = temp; + temp = (temp * 5 + 128) >> 8; + SEGGER_RTT_printf(0, "temp is %d", temp/100); + tempf = (float)temp; + + return (tempf/100.0f); +} + +float BME280_SPI::getPressure() +{ + uint32_t press_raw; + float pressf; + char cmd[3]; + + _cs = 0; + _spi.write(0xf7); // press_msb + for(int i = 0; i < 3; i++) + cmd[i] = _spi.write(0); + _cs = 1; + + press_raw = (cmd[0] << 12) | (cmd[1] << 4) | (cmd[2] >> 4); + + int32_t var1, var2; + uint32_t press; + + var1 = (t_fine >> 1) - 64000; + var2 = (((var1 >> 2) * (var1 >> 2)) >> 11) * dig_P6; + var2 = var2 + ((var1 * dig_P5) << 1); + var2 = (var2 >> 2) + (dig_P4 << 16); + var1 = (((dig_P3 * (((var1 >> 2)*(var1 >> 2)) >> 13)) >> 3) + ((dig_P2 * var1) >> 1)) >> 18; + var1 = ((32768 + var1) * dig_P1) >> 15; + if (var1 == 0) { + return 0; + } + press = (((1048576 - press_raw) - (var2 >> 12))) * 3125; + if(press < 0x80000000) { + press = (press << 1) / var1; + } else { + press = (press / var1) * 2; + } + var1 = ((int32_t)dig_P9 * ((int32_t)(((press >> 3) * (press >> 3)) >> 13))) >> 12; + var2 = (((int32_t)(press >> 2)) * (int32_t)dig_P8) >> 13; + press = (press + ((var1 + var2 + dig_P7) >> 4)); + SEGGER_RTT_printf(0, "pressure is %d", press/100); + + pressf = (float)press; + return (pressf/100.0f); +} + +float BME280_SPI::getHumidity() +{ + uint32_t hum_raw; + float humf; + char cmd[2]; + + _cs = 0; + _spi.write(0xfd); // hum_msb + for(int i = 0; i < 2; i++) + cmd[i] = _spi.write(0); + _cs = 1; + + hum_raw = (cmd[0] << 8) | cmd[1]; + + int32_t v_x1; + + v_x1 = t_fine - 76800; + v_x1 = (((((hum_raw << 14) -(((int32_t)dig_H4) << 20) - (((int32_t)dig_H5) * v_x1)) + + ((int32_t)16384)) >> 15) * (((((((v_x1 * (int32_t)dig_H6) >> 10) * + (((v_x1 * ((int32_t)dig_H3)) >> 11) + 32768)) >> 10) + 2097152) * + (int32_t)dig_H2 + 8192) >> 14)); + v_x1 = (v_x1 - (((((v_x1 >> 15) * (v_x1 >> 15)) >> 7) * (int32_t)dig_H1) >> 4)); + v_x1 = (v_x1 < 0 ? 0 : v_x1); + v_x1 = (v_x1 > 419430400 ? 419430400 : v_x1); + SEGGER_RTT_printf(0, "humidity is %d", (v_x1 >> 12)/1024); + + humf = (float)(v_x1 >> 12); + + return (humf/1024.0f); +}