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stm32samples/F1-nolib/BMP180/BMP180.c
Edward Emelianov 9573221c5f add BMP180
2021-02-21 23:46:43 +03:00

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/*
* This file is part of the BMP180 project.
* Copyright 2021 Edward V. Emelianov <edward.emelianoff@gmail.com>.
*
* This program 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
* (at your option) any later version.
*
* This program 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 this program. If not, see <http://www.gnu.org/licenses/>.
*/
#include "i2c.h"
#include "BMP180.h"
//#define EBUG
#ifdef EBUG
#include "usb.h"
#include "proto.h"
#define DBG(x) do{USB_send(x);}while(0)
#else
#define DBG(x)
#endif
#define BMP180_I2C_ADDRESS (0x77)
/**
* BMP180 registers
*/
#define BMP180_REG_OXLSB (0xF8)
#define BMP180_REG_OLSB (0xF7)
#define BMP180_REG_OMSB (0xF6)
#define BMP180_REG_OUT (BMP180_REG_OMSB)
#define BMP180_REG_CTRLMEAS (0xF4)
#define BMP180_REG_SOFTRESET (0xE0)
#define BMP180_REG_ID (0xD0)
#define BMP180_REG_CALIB (0xAA)
// shift for oversampling
#define BMP180_CTRLM_OSS_SHIFT (6)
// start measurement
#define BMP180_CTRLM_SCO (1<<5)
// write it to BMP180_REG_SOFTRESET for soft reset
#define BMP180_SOFTRESET_VAL (0xB6)
// start measurement of T/P
#define BMP180_READ_T (0x0E)
#define BMP180_READ_P (0x14)
// delays in milliseconds
//#define BMP180_T_DELAY (2)
static BMP180_oversampling bmp180_os = BMP180_OVERS_2;
static struct {
int16_t AC1;
int16_t AC2;
int16_t AC3;
uint16_t AC4;
uint16_t AC5;
uint16_t AC6;
int16_t B1;
int16_t B2;
int16_t MB;
int16_t MC;
int16_t MD;
} __attribute__ ((packed)) CaliData = {0};
static BMP180_status bmpstatus = BMP180_NOTINIT;
static uint8_t calidata_rdy = 0;
static uint32_t milliseconds_start = 0; // time of measurement start
//static uint32_t p_delay = 8; // delay for P measurement
static uint8_t uncomp_data[3]; // raw uncompensated data
static int32_t Tval; // uncompensated T value
// compensated values:
static uint32_t Pmeasured; // in Pa
static int32_t Tmeasured; // /10degC
static uint8_t devID = 0;
BMP180_status BMP180_get_status(){
return bmpstatus;
}
void BMP180_setOS(BMP180_oversampling os){
bmp180_os = os & 0x03;
/*
switch(os){
case BMP180_OVERS_1:
p_delay = 5;
break;
case BMP180_OVERS_2:
p_delay = 8;
break;
case BMP180_OVERS_4:
p_delay = 14;
break;
default:
p_delay = 26;
}*/
}
static int read_reg8(uint8_t reg, uint8_t *val){
if(I2C_OK != i2c_7bit_send_onebyte(reg, 0)) return 0;
if(I2C_OK != i2c_7bit_receive_onebyte(val, 1)) return 0;
return 1;
}
static int write_reg8(uint8_t reg, uint8_t val){
uint8_t d[2] = {reg, val};
if(I2C_OK != i2c_7bit_send(d, 2)) return 0;
return 1;
}
// get compensation data, return 1 if OK
static int readcompdata(){
if(I2C_OK != i2c_7bit_send_onebyte(BMP180_REG_CALIB, 0)) return 0;
if(I2C_OK != i2c_7bit_receive((uint8_t*)&CaliData, sizeof(CaliData))) return 0;
// convert big-endian into little-endian
uint8_t *d, val;
uint16_t *arr = (uint16_t*)&CaliData;
for(int i = 0; i < (int)sizeof(CaliData)/2; ++i){
d = (uint8_t*)(&arr[i]);
val = d[0];
d[0] = d[1];
d[1] = val;
}
calidata_rdy = 1;
return 1;
}
// do a soft-reset procedure
int BMP180_reset(){
if(!write_reg8(BMP180_REG_SOFTRESET, BMP180_SOFTRESET_VAL)){
DBG("Can't reset\n");
return 0;
}
return 1;
}
// read compensation data & write registers
int BMP180_init(){
bmpstatus = BMP180_NOTINIT;
i2c_setup();
i2c_set_addr7(BMP180_I2C_ADDRESS);
if(!read_reg8(BMP180_REG_ID, &devID)) return 0;
DBG("Got device ID: "); DBG(u2str(devID)); DBG("\n");
if(devID != BMP180_CHIP_ID){
DBG("Not BMP180\n");
return 0;
}
if(!readcompdata()){
DBG("Can't read calibration data\n");
}else{
DBG("AC1=");
DBG(i2str(CaliData.AC1)); DBG(", AC2="); DBG(i2str(CaliData.AC2)); DBG(", AC3=");
DBG(i2str(CaliData.AC3)); DBG(", AC4="); DBG(u2str(CaliData.AC4)); DBG(", AC5=");
DBG(u2str(CaliData.AC5)); DBG(", AC6="); DBG(u2str(CaliData.AC6)); DBG(", B1=");
DBG(i2str(CaliData.B1)); DBG(", B2="); DBG(i2str(CaliData.B2)); DBG(", MB=");
DBG(i2str(CaliData.MB)); DBG(", MC="); DBG(i2str(CaliData.MC)); DBG(", MD=");
DBG(i2str(CaliData.MD)); DBG("\n");
}
return 1;
}
// @return 1 if OK, *devid -> BMP/BME
void BMP180_read_ID(uint8_t *devid){
*devid = devID;
}
// start measurement, @return 1 if all OK
int BMP180_start(uint32_t curr_milliseconds){
if(!calidata_rdy || bmpstatus == BMP180_BUSYT || bmpstatus == BMP180_BUSYP) return 0;
uint8_t reg = BMP180_READ_T | BMP180_CTRLM_SCO;
if(!write_reg8(BMP180_REG_CTRLMEAS, reg)){
DBG("Can't write CTRL reg\n");
return 0;
}
bmpstatus = BMP180_BUSYT;
milliseconds_start = curr_milliseconds;
return 1;
}
// calculate T/10 degC and P in Pa
static inline void compens(uint32_t Pval){
// T:
int32_t X1 = ((Tval - CaliData.AC6)*CaliData.AC5) >> 15;
int32_t X2 = (CaliData.MC << 11) / (X1 + CaliData.MD);
int32_t B5 = X1 + X2;
Tmeasured = (B5 + 8) >> 4;
// P:
int32_t B6 = B5 - 4000;
X1 = (CaliData.B2 * ((B6*B6) >> 12)) >> 11;
X2 = (CaliData.AC2 * B6) >> 11;
int32_t X3 = X1 + X2;
int32_t B3 = ((((CaliData.AC1 << 2) + X3) << bmp180_os) + 2) >> 2;
X1 = (CaliData.AC3 * B6) >> 13;
X2 = (CaliData.B1 * ((B6 * B6) >> 12)) >> 16;
X3 = ((X1 + X2) + 2) >> 2;
uint32_t B4 = (CaliData.AC4 * (uint32_t) (X3 + 32768)) >> 15;
uint32_t B7 = (uint32_t)(Pval - B3) * (50000 >> bmp180_os);
if(B7 < 0x80000000){
Pmeasured = (B7 << 1) / B4;
}else{
Pmeasured = (B7 / B4) << 1;
}
X1 = Pmeasured >> 8;
X1 *= X1;
X1 = (X1 * 3038) >> 16;
X2 = (-7357 * Pmeasured) >> 16;
Pmeasured += (X1 + X2 + 3791) >> 4;
}
static int still_measuring(){
uint8_t reg;
if(!read_reg8(BMP180_REG_CTRLMEAS, &reg)) return 1;
if(reg & BMP180_CTRLM_SCO){
DBG("Still measure\n");
return 1;
}
return 0;
}
void BMP180_process(uint32_t curr_milliseconds){
uint8_t reg;
if(bmpstatus != BMP180_BUSYT && bmpstatus != BMP180_BUSYP) return;
if(bmpstatus == BMP180_BUSYT){ // wait for temperature
//if(curr_milliseconds - milliseconds_start < BMP180_T_DELAY) return;
if(still_measuring()) return;
// get uncompensated data
DBG("Read uncompensated T\n");
if(I2C_OK != i2c_7bit_send_onebyte(BMP180_REG_OUT, 0)){
bmpstatus = BMP180_ERR;
return;
}
if(I2C_OK != i2c_7bit_receive(uncomp_data, 2)){
bmpstatus = BMP180_ERR;
return;
}
Tval = uncomp_data[0] << 8 | uncomp_data[1];
DBG("Start P measuring\n");
reg = BMP180_READ_P | BMP180_CTRLM_SCO | (bmp180_os << BMP180_CTRLM_OSS_SHIFT);
if(!write_reg8(BMP180_REG_CTRLMEAS, reg)){
bmpstatus = BMP180_ERR;
return;
}
milliseconds_start = curr_milliseconds;
bmpstatus = BMP180_BUSYP;
}else{ // wait for pressure
//if(curr_milliseconds - milliseconds_start < p_delay) return;
if(still_measuring()) return;
DBG("Read uncompensated P\n");
if(I2C_OK != i2c_7bit_send_onebyte(BMP180_REG_OUT, 0)){
bmpstatus = BMP180_ERR;
return;
}
if(I2C_OK != i2c_7bit_receive(uncomp_data, 3)){
bmpstatus = BMP180_ERR;
return;
}
uint32_t Pval = uncomp_data[0] << 16 | uncomp_data[1] << 8 | uncomp_data[2];
Pval >>= (8 - bmp180_os);
// calculate compensated values
compens(Pval);
DBG("All data ready\n");
bmpstatus = BMP180_RDY; // data ready
}
}
// read data & convert it
void BMP180_getdata(int32_t *T, uint32_t *P){
*T = Tmeasured;
*P = Pmeasured;
bmpstatus = BMP180_RELAX;
}
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