basic bmp280 lib (mostly adafruit reimplementation) and example

2 files changed, 292 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
diff --git a/lib/bmp280.h b/lib/bmp280.h
new file mode 100644
index 0000000..22472e3
--- /dev/null
+++ b/lib/bmp280.h
@@ -0,0 +1,107 @@
+/*
+ *  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/>.
+ */
+
+#ifndef SPREADAVR_bmp280_h_INCLUDED
+#define SPREADAVR_bmp280_h_INCLUDED
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#define BMP280_AVERAGE_SEA_LEVEL_PRESSURE 1013.25
+#define BMP280_LUFA_SPIO_OPTIONS SPI_SPEED_FCPU_DIV_16  | SPI_MODE_MASTER | SPI_ORDER_MSB_FIRST | SPI_SCK_LEAD_RISING | SPI_SAMPLE_LEADING
+
+/*=========================================================================
+    REGISTERS
+    -----------------------------------------------------------------------*/
+    enum
+    {
+      BMP280_REGISTER_DIG_T1              = 0x88,
+      BMP280_REGISTER_DIG_T2              = 0x8A,
+      BMP280_REGISTER_DIG_T3              = 0x8C,
+
+      BMP280_REGISTER_DIG_P1              = 0x8E,
+      BMP280_REGISTER_DIG_P2              = 0x90,
+      BMP280_REGISTER_DIG_P3              = 0x92,
+      BMP280_REGISTER_DIG_P4              = 0x94,
+      BMP280_REGISTER_DIG_P5              = 0x96,
+      BMP280_REGISTER_DIG_P6              = 0x98,
+      BMP280_REGISTER_DIG_P7              = 0x9A,
+      BMP280_REGISTER_DIG_P8              = 0x9C,
+      BMP280_REGISTER_DIG_P9              = 0x9E,
+
+      BMP280_REGISTER_CHIPID             = 0xD0,
+      BMP280_REGISTER_VERSION            = 0xD1,
+      BMP280_REGISTER_SOFTRESET          = 0xE0,
+
+      BMP280_REGISTER_CAL26              = 0xE1,  // R calibration stored in 0xE1-0xF0
+
+      BMP280_REGISTER_CONTROL            = 0xF4,
+      BMP280_REGISTER_CONFIG             = 0xF5,
+      BMP280_REGISTER_PRESSUREDATA       = 0xF7,
+      BMP280_REGISTER_TEMPDATA           = 0xFA,
+    };
+
+/*=========================================================================*/
+
+
+/*=========================================================================
+    CALIBRATION DATA
+    -----------------------------------------------------------------------*/
+    typedef struct
+    {
+      volatile uint8_t *cs_port;
+      uint8_t  cs_pin;
+      uint16_t dig_T1;
+      int16_t  dig_T2;
+      int16_t  dig_T3;
+
+      uint16_t dig_P1;
+      int16_t  dig_P2;
+      int16_t  dig_P3;
+      int16_t  dig_P4;
+      int16_t  dig_P5;
+      int16_t  dig_P6;
+      int16_t  dig_P7;
+      int16_t  dig_P8;
+      int16_t  dig_P9;
+
+      uint8_t  dig_H1;
+      int16_t  dig_H2;
+      uint8_t  dig_H3;
+      int16_t  dig_H4;
+      int16_t  dig_H5;
+      int8_t   dig_H6;
+    } bmp280_sensor;
+/*=========================================================================*/
+
+
+//make sure to configure the cs_pin as OUTPUT beforehand
+//make sure to configure SPI beforehand
+void bmp280_init(bmp280_sensor *sensor, volatile uint8_t *cs_port, uint8_t cs_pin);
+float bmp280_readTemp(bmp280_sensor *sensor);
+float bmp280_readPressure(bmp280_sensor *sensor);
+float bmp280_readAltitude(bmp280_sensor *sensor, float sealevelp);
+
+
+#endif
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