MPL115A2 (I2C) Pressure sensor interface
Dependents: MPL115A2Sample dataloger_for_modelrocket ARLISS2012_Hidaka
Diff: MPL115A2.cpp
- Revision:
- 2:d77bd4340924
--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/MPL115A2.cpp Sat May 14 17:29:51 2011 +0000 @@ -0,0 +1,47 @@ +#include "MPL115A2.h" + +#define c2f(ch, cl, nbits, fbits, zpad) float(short(ch << 8 | cl) >> 16 - nbits) / (1 << fbits + zpad) + +int MPL115A2::read(float *pressure, char *data) { + const char id = 0x60 << 1; + char cmd[2] = {0x12, 0x01}; // read both + char buf[16]; + + if (i2c.write(id, cmd, 2) != 0) + return -1; + + wait_ms(1); + + cmd[0] = 0; + + if (i2c.write(id, cmd, 1, true) != 0) + return -1; + + if (i2c.read(id, buf, 16) == 0) { + float padc = buf[0] << 2 | buf[1] >> 6; + float tadc = buf[2] << 2 | buf[3] >> 6; + float a0 = c2f(buf[4], buf[5], 16, 3, 0); + float b1 = c2f(buf[6], buf[7], 16, 13, 0); + float b2 = c2f(buf[8], buf[9], 16, 14, 0); + float c12 = c2f(buf[10], buf[11], 14, 13, 9); + float c11 = c2f(buf[12], buf[13], 11, 10, 11); + float c22 = c2f(buf[14], buf[15], 11, 10, 15); + + float pcomp = a0 + (b1 + c11 * padc + c12 * tadc) * padc + (b2 + c22 * tadc) * tadc; + + if (pressure != 0) + *pressure = pcomp * 650 / 1023 + 500; + + if (data != 0) + memcpy(data, buf, 16); + + return 0; + } + + return -1; +} + +float MPL115A2::readPressure() { + float pressure; + return read(&pressure, 0) == 0 ? pressure : 0; +} \ No newline at end of file