ESP8266 Community Forum

- Sat Jun 06, 2015 4:59 pm #19689 Any comparison appreciated. I'm sure this can't be right but temperature is ok

Peter Scargill - http://tech.scargill.net

- Sat Jun 06, 2015 5:13 pm #19692

Any comparison appreciated. I'm sure this can't be right but temperature is ok

Looks to me just a wrong factor of 100 in the mbar value. Maybe some confused Pa with mbar.

Can't tell without seeing the code.

Cal

P.S.
Did you notice viewtopic.php?f=9&t=3447?

Get your modules here:

https://www.banggood.com/custlink/KvGGhGF4wG

- Sat Jun 06, 2015 5:44 pm #19696 It definitely says 101,000 mbar - ie crushing pressure. It's the code that came as an example with the Espressif setup.. here it is...

/*
The driver for the temperature sensor and pressure BMP180
Official repository: https://github.com/CHERTS/esp8266-i2c_bmp180
Base on https://github.com/reaper7/esp8266_i2c_bmp180
This driver depends on the I2C driver https://github.com/zarya/esp8266_i2c_driver/

Copyright (C) 2014 reaper7
Copyright (C) 2014 Mikhail Grigorev (CHERTS)

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 2 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, write to the Free Software Foundation, Inc.,
51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*/

#include <math.h>
#include "driver/i2c.h"
#include "driver/i2c_bmp180.h"

int16_t ac1, ac2, ac3;
uint16_t ac4, ac5, ac6;
int16_t b1, b2;
int16_t mb, mc, md;

int16_t ICACHE_FLASH_ATTR BMP180_readRegister16(uint8_t reg)
{
i2c_start();
i2c_writeByte(BMP180_W);
if(!i2c_check_ack()){
#ifdef BMP180_DEBUG
//os_printf("slave not ack..\n return \n");
ets_uart_printf("BMP180_readRegister16: i2c_writeByte(0xEE) slave not ack..\r\nreturn\r\n");
#endif
i2c_stop();
return(0);
}
i2c_writeByte(reg);
if(!i2c_check_ack()){
#ifdef BMP180_DEBUG
//os_printf("slave not ack..\n return \n");
ets_uart_printf("BMP180_readRegister16: i2c_writeByte(reg) slave not ack..\r\nreturn\r\n");
#endif
i2c_stop();
return(0);
}
i2c_start();
i2c_writeByte(BMP180_R);
if(!i2c_check_ack()){
#ifdef BMP180_DEBUG
//os_printf("slave not ack..\n return \n");
ets_uart_printf("BMP180_readRegister16: i2c_writeByte(0xEF) slave not ack..\r\nreturn\r\n");
#endif
i2c_stop();
return(0);
}
uint8_t msb = i2c_readByte();
i2c_send_ack(1);
uint8_t lsb = i2c_readByte();
i2c_send_ack(0);
i2c_stop();
int16_t res = (msb << 8) + lsb;
//int16_t res = (msb << 8) | lsb;
return res;
}

int16_t ICACHE_FLASH_ATTR BMP180_readExRegister16(uint8_t reg, enum PRESSURE_RESOLUTION resolution)
{
i2c_start();
i2c_writeByte(BMP180_W);
if(!i2c_check_ack()){
#ifdef BMP180_DEBUG
//os_printf("slave not ack..\n return \n");
ets_uart_printf("BMP180_readExRegister16: i2c_writeByte(0xEE) slave not ack..\r\nreturn\r\n");
#endif
i2c_stop();
return(0);
}
i2c_writeByte(reg);
if(!i2c_check_ack()){
#ifdef BMP180_DEBUG
//os_printf("slave not ack..\n return \n");
ets_uart_printf("BMP180_readExRegister16: i2c_writeByte(reg) slave not ack..\r\nreturn\r\n");
#endif
i2c_stop();
return(0);
}
i2c_start();
i2c_writeByte(BMP180_R);
if(!i2c_check_ack()){
#ifdef BMP180_DEBUG
//os_printf("slave not ack..\n return \n");
ets_uart_printf("BMP180_readExRegister16: i2c_writeByte(0xEF) slave not ack..\r\nreturn\r\n");
#endif
i2c_stop();
return(0);
}
uint8_t msb = i2c_readByte();
i2c_send_ack(1);
uint8_t lsb = i2c_readByte();
i2c_send_ack(0);
uint8_t xlsb = i2c_readByte();
i2c_send_ack(0);
i2c_stop();
int32_t res = ((msb << 16) + (lsb << 8) + xlsb) >> (8-resolution);
return res;
}

int16_t ICACHE_FLASH_ATTR BMP180_readRawValue(uint8_t cmd)
{
i2c_start();
i2c_writeByte(BMP180_W);
if(!i2c_check_ack()){
#ifdef BMP180_DEBUG
//os_printf("slave not ack..\n return \n");
ets_uart_printf("BMP180_readRawValue: i2c_writeByte(0xEE) slave not ack..\r\nreturn\r\n");
#endif
i2c_stop();
return(0);
}
i2c_writeByte(BMP180_CTRL_REG);
if(!i2c_check_ack()){
#ifdef BMP180_DEBUG
//os_printf("slave not ack..\n return \n");
ets_uart_printf("BMP180_readRawValue: i2c_writeByte(0xF4) slave not ack..\r\nreturn\r\n");
#endif
i2c_stop();
return(0);
}
i2c_writeByte(cmd);
if(!i2c_check_ack()){
#ifdef BMP180_DEBUG
//os_printf("slave not ack..\n return \n");
ets_uart_printf("BMP180_readRawValue: i2c_writeByte(cmd) slave not ack..\r\nreturn\r\n");
#endif
i2c_stop();
return(0);
}
i2c_stop();
os_delay_us(CONVERSION_TIME*900); // max time is 4.5ms
int16_t res = BMP180_readRegister16(BMP180_DATA_REG);
return res;
}

int16_t ICACHE_FLASH_ATTR BMP180_readExRawValue(uint8_t cmd, enum PRESSURE_RESOLUTION resolution)
{
i2c_start();
i2c_writeByte(BMP180_W);
if(!i2c_check_ack()){
#ifdef BMP180_DEBUG
//os_printf("slave not ack..\n return \n");
ets_uart_printf("BMP180_readExRawValue: i2c_writeByte(0xEE) slave not ack..\r\nreturn\r\n");
#endif
i2c_stop();
return(0);
}
i2c_writeByte(BMP180_CTRL_REG);
if(!i2c_check_ack()){
#ifdef BMP180_DEBUG
//os_printf("slave not ack..\n return \n");
ets_uart_printf("BMP180_readExRawValue: i2c_writeByte(0xF4) slave not ack..\r\nreturn\r\n");
#endif
i2c_stop();
return(0);
}
i2c_writeByte(cmd);
if(!i2c_check_ack()){
#ifdef BMP180_DEBUG
//os_printf("slave not ack..\n return \n");
ets_uart_printf("BMP180_readExRawValue: i2c_writeByte(cmd) slave not ack..\r\nreturn\r\n");
#endif
i2c_stop();
return(0);
}
i2c_stop();
switch(resolution)
{
case OSS_0:
os_delay_us(CONVERSION_TIME*900);
break;
case OSS_1:
os_delay_us(CONVERSION_TIME*1500);
break;
case OSS_2:
os_delay_us(CONVERSION_TIME*2700);
break;
case OSS_3:
os_delay_us(CONVERSION_TIME*5100);
break;
default:
os_delay_us(CONVERSION_TIME*900);
}
int16_t res = BMP180_readExRegister16(BMP180_DATA_REG, resolution);
return res;
}

bool ICACHE_FLASH_ATTR BMP180_Init()
{
i2c_init();
int16_t version = BMP180_readRegister16(BMP180_CHIP_ID_REG);
if (version != BMP180_CHIP_ID) {
#ifdef BMP180_DEBUG
char temp[80];
os_sprintf(temp, "BMP180: wanted chip id 0x%X, found chip id 0x%X\r\n",
BMP180_CHIP_ID, version);
ets_uart_printf(temp);
#endif
return 0;
}

if (!BMP180_readRegister16(BMP180_VERSION_REG))
return 0;

#ifdef BMP180_DEBUG
//os_printf("BMP180 read calibration data...\r\n");
ets_uart_printf("BMP180 read calibration data...\r\n");
#endif
ac1 = BMP180_readRegister16(0xAA);
ac2 = BMP180_readRegister16(0xAC);
ac3 = BMP180_readRegister16(0xAE);
ac4 = BMP180_readRegister16(0xB0);
ac5 = BMP180_readRegister16(0xB2);
ac6 = BMP180_readRegister16(0xB4);
b1 = BMP180_readRegister16(0xB6);
b2 = BMP180_readRegister16(0xB8);
mb = BMP180_readRegister16(0xBA);
mc = BMP180_readRegister16(0xBC);
md = BMP180_readRegister16(0xBE);

#ifdef BMP180_DEBUG
ets_uart_printf("BMP180_Calibration:\r\n");
char temp[128];
os_sprintf(temp, "AC1: %ld, AC2: %ld, AC3: %ld, AC4: %ld, AC5: %ld, AC6: %ld, B1: %ld, B2: %ld, MB: %ld, MC: %ld, MD: %ld\r\n",
ac1, ac2, ac3, ac4, ac5, ac6, b1, b2, mb, mc, md);
ets_uart_printf(temp);
#endif
return 1;
}

int32_t ICACHE_FLASH_ATTR BMP180_GetTemperature()
{
int32_t UT;
int32_t B5, X1, X2, T;
UT = BMP180_readRawValue(BMP_CMD_MEASURE_TEMP);
X1 = (UT - (int32_t)ac6) * ((int32_t)ac5) >> 15;
X2 = ((int32_t)mc << 11) / (X1 + (int32_t)md);
B5 = X1 + X2;
T = (B5+8) >> 4;
return (T);
}

int32_t ICACHE_FLASH_ATTR BMP180_GetPressure(enum PRESSURE_RESOLUTION resolution)
{
int32_t UT;
uint16_t UP;
int32_t B3, B5, B6;
uint32_t B4, B7;
int32_t X1, X2, X3;
int32_t P;
UT = BMP180_readRawValue(BMP_CMD_MEASURE_TEMP);
UP = BMP180_readExRawValue(BMP_CMD_MEASURE_PRESSURE_0+(resolution<<6), resolution);
// Calculate temperature
X1 = (UT - (int32_t)ac6) * ((int32_t)ac5) >> 15;
X2 = ((int32_t)mc << 11) / (X1 + (int32_t)md);
B5 = X1 + X2;
// Calculate pressure
B6 = B5 - 4000;
X1 = ((int32_t)b2 * ((B6 * B6) >> 12)) >> 11;
X2 = ((int32_t)ac2 * B6) >> 11;
X3 = X1 + X2;
B3 = (((((int32_t) ac1) * 4 + X3)<<resolution) + 2)>> 2;
X1 = ((int32_t)ac3 * B6) >> 13;
X2 = ((int32_t)b1 * ((B6 * B6) >> 12)) >> 16;
X3 = ((X1 + X2) + 2) >> 2;
B4 = ((uint32_t)ac4 * (uint32_t)(X3 + 32768)) >> 15;
B7 = ((uint32_t) (UP - B3) * (50000 >> resolution));
if (B7 < 0x80000000) {
P = (B7 * 2) / B4;
} else {
P = (B7 / B4) * 2;
}
X1 = (P >> 8) * (P >> 8);
X1 = (X1 * 3038) >> 16;
X2 = (-7357 * P) >> 16;
P = P + ((X1 + X2 + (int32_t)3791) >> 4);
return P;
}

int32_t ICACHE_FLASH_ATTR BMP180_CalcAltitude(int32_t pressure)
{
return (int32_t)(pow(((float)MYALTITUDE/44330)+1,5.255F)*pressure);
}

char* ICACHE_FLASH_ATTR BMP180_Int2String(char* buffer, int32_t value)
{
os_sprintf(buffer, "%d.%d", (int)(value/10), (int)(value%10));
return buffer;
}

char* ICACHE_FLASH_ATTR BMP180_Float2String(char* buffer, float value)
{
os_sprintf(buffer, "%d.%d", (int)(value),(int)((value - (int)value)*100));
return buffer;
}

Peter Scargill - http://tech.scargill.net

- Sat Jun 06, 2015 5:53 pm #19697 But thats only the reading of the values not the printing.
Following the link in the source code lead me to

https://github.com/CHERTS/esp8266-i2c_b ... ser_main.c

Which prints the pressure in Pa which should be your 100.000 value.
Please look at your code that prints the pressure.

Cal

Get your modules here:

https://www.banggood.com/custlink/KvGGhGF4wG