pressure
MPL3115.cpp
- Committer:
- otis22894
- Date:
- 2016-12-11
- Revision:
- 0:01659d3a8c37
File content as of revision 0:01659d3a8c37:
/* Copyright (c) 2015 NXP Semiconductors. MIT License * * Permission is hereby granted, free of charge, to any person obtaining a copy of this software * and associated documentation files (the "Software"), to deal in the Software without * restriction, including without limitation the rights to use, copy, modify, merge, publish, * distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the * Software is furnished to do so, subject to the following conditions: * * The above copyright notice and this permission notice shall be included in all copies or * substantial portions of the Software. * * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING * BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, * DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. */ #include "MPL3115.h" #include "mbed.h" #define REG_PRESSURE_MSB 0x01 MPL3115::MPL3115(PinName sda, PinName scl, int addr) : MPL3115_i2c(sda,scl), m_addr(addr) { } void MPL3115::config(void) { char d[2]; d[0] = MPL3115_CTRL_REG1; //Puts device in Standby mode d[1] = 0x00; MPL3115_i2c.write(MPL3115_I2C_ADDRESS, d,2); d[0] = MPL3115_CTRL_REG1; //Puts device in Active mode and in altimeter mode d[1] = 0x81; MPL3115_i2c.write(MPL3115_I2C_ADDRESS, d, 2); } float MPL3115::getPressure(void) { float a; a = getPressure(REG_PRESSURE_MSB); return a; } float MPL3115::getPressure(unsigned char reg) { unsigned char dt[3]; unsigned int prs; int tmp; float fprs; /* * dt[0] = Bits 12-19 of 20-bit real-time Pressure sample. (b7-b0) * dt[1] = Bits 4-11 of 20-bit real-time Pressure sample. (b7-b0) * dt[2] = Bits 0-3 of 20-bit real-time Pressure sample (b7-b4) */ readRegs( reg, &dt[0], 3); prs = ((dt[0]<<10) | (dt[1]<<2) | (dt[2]>>6)); // if ( dt[0] > 0x7f) { // negative number if ( dt[0] & 0x80) prs |= 0xFFFC0000; else prs |= 0xFFFE0000; tmp = ~prs + 1; // make the complemets. At this point all the bits are inverted. fprs = (float)tmp * -1.0f; } else { fprs = (float)prs * 1.0f; } if ( dt[2] & 0x10) fprs += 0.25f; if ( dt[2] & 0x20) fprs += 0.5f; return fprs; } void MPL3115::readRegs(int addr, uint8_t * data, int len) { char t[1] = {addr}; MPL3115_i2c.write(m_addr, t, 1, true); MPL3115_i2c.read(m_addr, (char *)data, len); }