Ryan Williams / MPL3115

pressure

Dependents:   xtrinsic_sensors

MPL3115.cpp@0:01659d3a8c37, 2016-12-11 (annotated)

Committer:
otis22894
Date:
Sun Dec 11 21:12:09 2016 +0000
Revision:
0:01659d3a8c37
First commit

Who changed what in which revision?

UserRevisionLine numberNew contents of line
otis22894 0:01659d3a8c37 1 /* Copyright (c) 2015 NXP Semiconductors. MIT License
otis22894 0:01659d3a8c37 2 *
otis22894 0:01659d3a8c37 3 * Permission is hereby granted, free of charge, to any person obtaining a copy of this software
otis22894 0:01659d3a8c37 4 * and associated documentation files (the "Software"), to deal in the Software without
otis22894 0:01659d3a8c37 5 * restriction, including without limitation the rights to use, copy, modify, merge, publish,
otis22894 0:01659d3a8c37 6 * distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the
otis22894 0:01659d3a8c37 7 * Software is furnished to do so, subject to the following conditions:
otis22894 0:01659d3a8c37 8 *
otis22894 0:01659d3a8c37 9 * The above copyright notice and this permission notice shall be included in all copies or
otis22894 0:01659d3a8c37 10 * substantial portions of the Software.
otis22894 0:01659d3a8c37 11 *
otis22894 0:01659d3a8c37 12 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING
otis22894 0:01659d3a8c37 13 * BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
otis22894 0:01659d3a8c37 14 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,
otis22894 0:01659d3a8c37 15 * DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
otis22894 0:01659d3a8c37 16 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
otis22894 0:01659d3a8c37 17 */
otis22894 0:01659d3a8c37 18
otis22894 0:01659d3a8c37 19 #include "MPL3115.h"
otis22894 0:01659d3a8c37 20 #include "mbed.h"
otis22894 0:01659d3a8c37 21 #define REG_PRESSURE_MSB 0x01
otis22894 0:01659d3a8c37 22
otis22894 0:01659d3a8c37 23 MPL3115::MPL3115(PinName sda, PinName scl, int addr) : MPL3115_i2c(sda,scl), m_addr(addr)
otis22894 0:01659d3a8c37 24 {
otis22894 0:01659d3a8c37 25
otis22894 0:01659d3a8c37 26 }
otis22894 0:01659d3a8c37 27
otis22894 0:01659d3a8c37 28 void MPL3115::config(void)
otis22894 0:01659d3a8c37 29 {
otis22894 0:01659d3a8c37 30 char d[2];
otis22894 0:01659d3a8c37 31 d[0] = MPL3115_CTRL_REG1; //Puts device in Standby mode
otis22894 0:01659d3a8c37 32 d[1] = 0x00;
otis22894 0:01659d3a8c37 33 MPL3115_i2c.write(MPL3115_I2C_ADDRESS, d,2);
otis22894 0:01659d3a8c37 34
otis22894 0:01659d3a8c37 35
otis22894 0:01659d3a8c37 36 d[0] = MPL3115_CTRL_REG1; //Puts device in Active mode and in altimeter mode
otis22894 0:01659d3a8c37 37 d[1] = 0x81;
otis22894 0:01659d3a8c37 38 MPL3115_i2c.write(MPL3115_I2C_ADDRESS, d, 2);
otis22894 0:01659d3a8c37 39
otis22894 0:01659d3a8c37 40 }
otis22894 0:01659d3a8c37 41
otis22894 0:01659d3a8c37 42
otis22894 0:01659d3a8c37 43 float MPL3115::getPressure(void)
otis22894 0:01659d3a8c37 44 {
otis22894 0:01659d3a8c37 45 float a;
otis22894 0:01659d3a8c37 46
otis22894 0:01659d3a8c37 47 a = getPressure(REG_PRESSURE_MSB);
otis22894 0:01659d3a8c37 48 return a;
otis22894 0:01659d3a8c37 49 }
otis22894 0:01659d3a8c37 50
otis22894 0:01659d3a8c37 51 float MPL3115::getPressure(unsigned char reg)
otis22894 0:01659d3a8c37 52 {
otis22894 0:01659d3a8c37 53 unsigned char dt[3];
otis22894 0:01659d3a8c37 54 unsigned int prs;
otis22894 0:01659d3a8c37 55 int tmp;
otis22894 0:01659d3a8c37 56 float fprs;
otis22894 0:01659d3a8c37 57
otis22894 0:01659d3a8c37 58 /*
otis22894 0:01659d3a8c37 59 * dt[0] = Bits 12-19 of 20-bit real-time Pressure sample. (b7-b0)
otis22894 0:01659d3a8c37 60 * dt[1] = Bits 4-11 of 20-bit real-time Pressure sample. (b7-b0)
otis22894 0:01659d3a8c37 61 * dt[2] = Bits 0-3 of 20-bit real-time Pressure sample (b7-b4)
otis22894 0:01659d3a8c37 62 */
otis22894 0:01659d3a8c37 63 readRegs( reg, &dt[0], 3);
otis22894 0:01659d3a8c37 64 prs = ((dt[0]<<10) | (dt[1]<<2) | (dt[2]>>6));
otis22894 0:01659d3a8c37 65 //
otis22894 0:01659d3a8c37 66 if ( dt[0] > 0x7f) {
otis22894 0:01659d3a8c37 67 // negative number
otis22894 0:01659d3a8c37 68 if ( dt[0] & 0x80)
otis22894 0:01659d3a8c37 69 prs |= 0xFFFC0000;
otis22894 0:01659d3a8c37 70 else
otis22894 0:01659d3a8c37 71 prs |= 0xFFFE0000;
otis22894 0:01659d3a8c37 72 tmp = ~prs + 1; // make the complemets. At this point all the bits are inverted.
otis22894 0:01659d3a8c37 73 fprs = (float)tmp * -1.0f;
otis22894 0:01659d3a8c37 74 } else {
otis22894 0:01659d3a8c37 75 fprs = (float)prs * 1.0f;
otis22894 0:01659d3a8c37 76 }
otis22894 0:01659d3a8c37 77
otis22894 0:01659d3a8c37 78 if ( dt[2] & 0x10)
otis22894 0:01659d3a8c37 79 fprs += 0.25f;
otis22894 0:01659d3a8c37 80 if ( dt[2] & 0x20)
otis22894 0:01659d3a8c37 81 fprs += 0.5f;
otis22894 0:01659d3a8c37 82
otis22894 0:01659d3a8c37 83 return fprs;
otis22894 0:01659d3a8c37 84 }
otis22894 0:01659d3a8c37 85 void MPL3115::readRegs(int addr, uint8_t * data, int len) {
otis22894 0:01659d3a8c37 86 char t[1] = {addr};
otis22894 0:01659d3a8c37 87 MPL3115_i2c.write(m_addr, t, 1, true);
otis22894 0:01659d3a8c37 88 MPL3115_i2c.read(m_addr, (char *)data, len);
otis22894 0:01659d3a8c37 89 }
otis22894 0:01659d3a8c37 90