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Gabriel
Joined: 03 Aug 2009
Posts: 1074
Location: Panama
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| BME280 - Kinda working maybe Driver |
 Posted: Mon Apr 02, 2018 6:26 am |
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Hi All,
I'm posting here my "working" efforts to get the BME280 working.
I get all 3 readings, but i really don't trust any of the values received although they are in the right ranges.
Any calculation relying on Dig_5 and Dig_4 I don't trust. You can see i have tried many interpretations of the formula to calculate these values...
All my mistakes and corrections are included commented out or not...
Overall I've had a terrible experience trying get this to work. I can't say I've put in "the extra mile" to get this to work properly... and by now i hate the sensor.
The idea of this post is for this to be a starting point and for others to contribute to get this to work...
Cludge Code Ahead:
| Code: |
#define BME280 0x77 //The I2C Address of the Device
void Write_BME_Register(int,int,int);
int Read_BME_Register(int,int);
void Get_BME_Data(int, int);
void Setup_BME();
void Calculate_Temp();
void Calculate_Hum();
void Calculate_Pess();
float Temperature;
signed int32 t_fine;
int32 Pressure;
int32 rawpres;
int32 rawtemp;
int32 rawhum;
int16 Dig_T1;
signed int16 Dig_T2;
signed int16 Dig_T3;
int16 Dig_H1;
signed int16 Dig_H2;
int16 Dig_H3;
signed int16 Dig_H4;
signed int16 Dig_H5;
signed int16 Dig_H6;
int16 Dig_P1;
signed int16 Dig_P2;
signed int16 Dig_P3;
signed int16 Dig_P4;
signed int16 Dig_P5;
signed int16 Dig_P6;
signed int16 Dig_P7;
signed int16 Dig_P8;
signed int16 Dig_P9;
void Setup_BME()
{
Write_BME_Register(BME280,0xF4,0x00); //Put it in sleep mode
delay_ms(2000);
Write_BME_Register(BME280,0xF5,0x84); //Set Config Word
Write_BME_Register(BME280,0xF2,0x04); //Set Humidity Control
Write_BME_Register(BME280,0xF4,0x93); //Set Temp & Press Control + Mode
Dig_T1 = make16 (Read_BME_Register(BME280,0x89),Read_BME_Register(BME280,0x88));
Dig_T2 = make16 (Read_BME_Register(BME280,0x8B),Read_BME_Register(BME280,0x8A));
Dig_T3 = make16 (Read_BME_Register(BME280,0x8D),Read_BME_Register(BME280,0x8C));
Dig_H1 = Read_BME_Register(BME280,0xA1);
Dig_H2 = make16 (Read_BME_Register(BME280,0xE2),Read_BME_Register(BME280,0xE1));
Dig_H3 = Read_BME_Register(BME280,0xE3);
Dig_H4=(((int16)Read_BME_Register(BME280,0xE4)<<4)|(Read_BME_Register(BME280,0xE5)& 0x0F)); //SO FAR BEST
Dig_H5 = make16((Read_BME_Register(BME280,0xE5)>>4), Read_BME_Register(BME280,0xE6));
// Dig_H4 = make16((Read_BME_Register(BME280,0xE4)<<4),(Read_BME_Register(BME280,0xE5)& 0x0F));
// Dig_H5 = make16((Read_BME_Register(BME280,0xE6)<<4), ((Read_BME_Register(BME280,0xE5)>>4)&0x0F));
// Dig_H4 = (Read_BME_Register(BME280,0xE4)<<4|(Read_BME_Register(BME280,0xE5) & 0x0F));
// Dig_H5 = (Read_BME_Register(BME280,0xE6)<<4|(Read_BME_Register(BME280,0xE5) >>4));
// Dig_H5 = make16((Read_BME_Register(BME280,0xE6)<<4),(Read_BME_Register(BME280,0xE5) >>4)); //SO FAR BEST
Dig_H6 = Read_BME_Register(BME280,0xE7);
Dig_P1 = make16 (Read_BME_Register(BME280,0x8F),Read_BME_Register(BME280,0x8E));
Dig_P2 = make16 (Read_BME_Register(BME280,0x91),Read_BME_Register(BME280,0x90));
Dig_P3 = make16 (Read_BME_Register(BME280,0x93),Read_BME_Register(BME280,0x92));
Dig_P4 = make16 (Read_BME_Register(BME280,0x95),Read_BME_Register(BME280,0x94));
Dig_P5 = make16 (Read_BME_Register(BME280,0x97),Read_BME_Register(BME280,0x96));
Dig_P6 = make16 (Read_BME_Register(BME280,0x99),Read_BME_Register(BME280,0x98));
Dig_P7 = make16 (Read_BME_Register(BME280,0x9B),Read_BME_Register(BME280,0x9A));
Dig_P8 = make16 (Read_BME_Register(BME280,0x9D),Read_BME_Register(BME280,0x9C));
Dig_P9 = make16 (Read_BME_Register(BME280,0x9F),Read_BME_Register(BME280,0x9E));
}
void Write_BME_Register(int Dev_Read_Add, int Register_add, int Data)
{
//int readbit =1;
//int writebit =0;
int tempaddress = 0;
tempaddress = Dev_Read_Add <<1; //Left Shift 1 bit to allow space for R/W bit
//tempaddress |= writebit; //OR the shifted address with the WRITE Bit
i2c_start();
i2c_write(tempaddress); //Address the device with shifted address with WRITE bit set
i2c_write(Register_add); //Tell the Device Which Register you want to read
i2c_write(Data);
i2c_stop();
}
int Read_BME_Register(int Dev_Read_Add, int Register_add)
{
//int readbit=1;
//int writebit=0;
int tempaddress=0;
int Result_Byte=0;
tempaddress = Dev_Read_Add <<1; //Left Shift 1 bit to allow space for R/W bit
// tempaddress |= 0x00; //OR the shifted address with the WRITE Bit
i2c_start(); //Start I2C sequence
i2c_write(tempaddress); //Address the device with shifted address with WRITE bit set
i2c_write(Register_add); //Tell the Device Which Register you want to read
// tempaddress = Dev_Read_Add <<1; //Left Shift 1 bit to allow space for R/W bit
tempaddress |= 0x01; //OR the shifted address with the READ Bit
i2c_start(); //Start I2C sequence
i2c_write(tempaddress); //Address the device with shifted address with READ bit set
Result_Byte = i2c_read(0); //READ the data onto a Variable - Device ID in this case
i2c_stop(); //Stop The I2C transaction
//fprintf(lcd_putc,"Register:%X\n\r", Result_Byte); //Print your Data --- For the Win.
return(Result_Byte);
}
void Calculate_Pess()
{
float var1, var2, p;
var1 = ((float)t_fine/2.0) - 64000.0;
var2 = var1 * var1 * ((float)Dig_P6) / 32768.0;
var2 = var2 + var1 * ((float)Dig_P5) * 2.0;
var2 = (var2/4.0)+(((float)Dig_P4) * 65536.0);
var1 = (((float)Dig_P3) * var1 * var1 / 524288.0 + ((float)Dig_P2) * var1) / 524288.0;
var1 = (1.0 + var1 / 32768.0)*((float)Dig_P1);
if (var1 == 0.0)
{
//return 0; // avoid exception caused by division by zero
}
p = 1048576.0 - (float)rawpres;
p = (p - (var2 / 4096.0)) * 6250.0 / var1;
var1 = ((float)Dig_P9) * p * p / 2147483648.0;
var2 = p * ((float)Dig_P8) / 32768.0;
p = p + (var1 + var2 + ((float)Dig_P7)) / 16.0;
fprintf(lcd_putc,"PRESSURE: %4.2f\n\r",(p/100.0)); //Print your Data --- For the Win.
}
void Calculate_Hum()
{
int32 var1;
var1 = (t_fine - ((int32)76800));
var1 = (((((rawhum << 14) - (((int32)Dig_H4) << 20) - (((int32)Dig_H5) * var1)) + ((int32)16384)) >> 15) * (((((((var1 * ((int32)Dig_H6)) >> 10) * (((var1 * ((int32)Dig_H3)) >> 11) + ((int32)32768))) >> 10) + ((int32)2097152)) *((int32)Dig_H2) + 8192) >> 14));
var1 = (var1 - (((((var1 >> 15) * (var1 >> 15)) >> 7) * ((int32)Dig_H1)) >> 4));
var1 = (var1 < 0 ? 0 : var1);
var1 = (var1 > 419430400 ? 419430400 : var1);
var1= var1>>12;
fprintf(lcd_putc,"HUMIDITY: %3.2f \n\r",((float)var1/1024.0)); //Print your Data --- For the Win.
}
void Calculate_Temp()
{
float var1, var2, T;
var1 = (((float)rawtemp)/16384.0 - ((float)Dig_T1)/1024.0) * ((float)Dig_T2);
var2 = ((((float)rawtemp)/131072.0 - ((float)Dig_T1)/8192.0) *
(((float)rawtemp)/131072.0 - ((float) Dig_T1)/8192.0)) * ((float)Dig_T3);
t_fine = (signed int32)(var1 + var2);
Temperature = (var1 + var2) / 5120.0;
fprintf(lcd_putc,"TEMPERATURE: %3.2f \n\r",Temperature); //Print your Data --- For the Win.
}
void Get_BME_Data(int Dev_Read_Add, int Register_add)
{
// int readbit =1;
// int writebit =0;
int tempaddress = 0;
int Temp[8];
tempaddress = Dev_Read_Add <<1; //Left Shift 1 bit to allow space for R/W bit
// tempaddress |= writebit; //OR the shifted address with the WRITE Bit
i2c_start(); //Start I2C sequence
i2c_write(tempaddress); //Address the device with shifted address with WRITE bit set
i2c_write(Register_add); //Tell the Device Which Register you want to read
// tempaddress = Dev_Read_Add <<1; //Left Shift 1 bit to allow space for R/W bit
tempaddress |= 0x01; //OR the shifted address with the READ Bit
i2c_start(); //Start I2C sequence
i2c_write(tempaddress); //Address the device with shifted address with READ bit set
Temp[0]= i2c_read(1); //0xF7
Temp[1]= i2c_read(1); //0xF8
Temp[2]= i2c_read(1); //0xF9
Temp[3]= i2c_read(1); //0xFa
Temp[4]= i2c_read(1); //0xFb
Temp[5]= i2c_read(1); //0xFc
Temp[6]= i2c_read(1); //0xFd
Temp[7]= i2c_read(0); //0xFe
i2c_stop(); //Stop The I2C transaction
rawpres = make32(0x00, Temp[0], Temp[1],Temp[2]);
rawpres >>= 4;
rawtemp = make32(0x00, Temp[3], Temp[4],Temp[5]);
rawtemp >>= 4;
rawhum = make32(0x00,0x00,Temp[6],Temp[7]);
} |
G.
_________________
CCS PCM 5.078 & CCS PCH 5.093 |
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Gabriel
Joined: 03 Aug 2009
Posts: 1074
Location: Panama
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| Posted: Mon Apr 02, 2018 6:33 am |
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To use the above:
Call the following functions in this order:
| Code: | Setup_BME();
Get_BME_Data(BME280, 0xF7);
Calculate_Temp();
Calculate_Hum();
Calculate_Pess(); |
_________________
CCS PCM 5.078 & CCS PCH 5.093 |
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Gabriel
Joined: 03 Aug 2009
Posts: 1074
Location: Panama
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| Posted: Sat Jul 14, 2018 6:56 am |
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Has anyone actually confirmed this driver works?
I would certainly appreciate a second pair of eyes on this... its a cool sensor but i had a lot of issues and not enough time to get it right.
G.
_________________
CCS PCM 5.078 & CCS PCH 5.093 |
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PCM programmer
Joined: 06 Sep 2003
Posts: 21708
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| Posted: Sun Aug 05, 2018 2:35 am |
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Probably no one has replied because CCS released their own driver file,
bme280.c, on 3/29/2016. It's included with the compiler.
Based on the release date, it would first be available in vs. 5.057, which
came out on 4/14/2016.
The CCS driver is fairly complicated. It has lots of math using signed
integers. It doesn't use floats.
Here is the file header:
| Code: | ///////////////////////////////////////////////////////////////////////////
//// ////
//// bme280.c ////
//// ////
//// Driver for Bosch BME280 Environmental sensor. This sensor can ////
//// read temperature, pressure and humidity. This driver returns ////
//// calibrated/compensated values by using the trim values on the ////
//// sensor. At this time this driver only supports I2C mode, it ////
//// doesn't support SPI mode. ////
//// ////
//// |
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Gabriel
Joined: 03 Aug 2009
Posts: 1074
Location: Panama
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| Posted: Sun Aug 05, 2018 12:13 pm |
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..... well that makes sense.
Thanks for the heads up.
I purchased 5.078 but im still running 5.012 until i deliver the project im currently working on.
Thanks
G.
_________________
CCS PCM 5.078 & CCS PCH 5.093 |
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shalts
Joined: 20 Oct 2006
Posts: 17
Location: Ankara
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| Posted: Sat Nov 03, 2018 7:58 am |
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| PCM programmer wrote: | Probably no one has replied because CCS released their own driver file,
bme280.c, on 3/29/2016. It's included with the compiler.
Based on the release date, it would first be available in vs. 5.057, which
came out on 4/14/2016. |
Hello,
So, does this mean if I update my compiler I will have this library included in my "drivers" folder ?
I have 5.026 right now.
Or, is there another way to get this library from CCS ?
Shalt
_________________
Murat Shalt Unal |
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PCM programmer
Joined: 06 Sep 2003
Posts: 21708
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| Posted: Sat Nov 03, 2018 12:30 pm |
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| shalts wrote: |
So, does this mean if I update my compiler I will have this library included in my "drivers" folder ?
I have 5.026 right now.
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That is correct.
| shalts wrote: |
Or, is there another way to get this library from CCS ?
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You could email CCS support and politely ask them if they would give
it to you. They might do it for one file. |
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shalts
Joined: 20 Oct 2006
Posts: 17
Location: Ankara
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| Posted: Sat Nov 03, 2018 3:23 pm |
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Oh. I didn't think that.
That would be really great ! Thanks a lot for your advice sir. I will try that on Monday.
On the other hand I am searching for the updates above my current version. Would be good to buy a 1 year update too.
Thanks a lot !
_________________
Murat Shalt Unal |
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