BME280[I2C] return same values using TWIM

RE: BME280[I2C] return same values using TWIM

haakonsh — Mon, 14 Oct 2019 15:29:52 GMT

I'm not familiar with that log structure, but it kinda looks like you're writing 0xF4 to the register with address 0xEC, then reading from the register with address 0xED, with both operations being successful.

Have you looked at Bosch's driver?

RE: BME280[I2C] return same values using TWIM

InvalidException — Mon, 14 Oct 2019 13:33:33 GMT

That was not issue as someone was already on Bosch site talking about it, just moved it inside function to read so will not be global (so will not have issue with compiler and volatile)

Problem still persist, getting same values and log that I posted from logic analyzer is specific for line

71 Setup Write to [0xEC] + ACK
72 0xF4 + ACK
73 Setup Read to [0xED] + ACK
74 0x00 + NAK

So writing to F4 returns ACK while reading data returns 0x00 and NAK

Will need to connect to Arduino and check if this is happening there also or something else is wrong 😞

RE: BME280[I2C] return same values using TWIM

haakonsh — Mon, 14 Oct 2019 12:19:19 GMT

I don't know the BME280, therefore, I don't know what you'd expect from this log and what is actually captured by the logical analyzer.

"The members that points to the addresses that the TWI peripheral uses for the transactions need to be declared as volatile." Did this solve your original issue?

RE: BME280[I2C] return same values using TWIM

InvalidException — Sun, 13 Oct 2019 23:11:44 GMT

After hooking I2C logic analyzer I got next results:

 Decoded Protocol Result
Setup Write to [0xEC] + ACK
0xD0 + ACK
Setup Read to [0xED] + ACK
0x60 + NAK
Setup Write to [0xEC] + ACK
0xB6 + ACK
Setup Write to [0xEC] + ACK
0x88 + ACK
Setup Read to [0xED] + ACK
0x4A + ACK
0x71 + ACK
0x25 + ACK
0x68 + ACK
0x32 + ACK
0x00 + ACK
0xE7 + ACK
0x89 + ACK
0xDA + ACK
0xD6 + ACK
0xD0 + ACK
0x0B + ACK
0x27 + ACK
0x19 + ACK
0xCA + ACK
0xFF + ACK
0xF9 + ACK
0xFF + ACK
0xAC + ACK
0x26 + ACK
0x0A + ACK
0xD8 + ACK
0xBD + ACK
0x10 + ACK
0x00 + ACK
0x4B + NAK
Setup Write to [0xEC] + ACK
0xE1 + ACK
Setup Read to [0xED] + ACK
0x60 + ACK
0x01 + ACK
0x00 + ACK
0x15 + ACK
0x28 + ACK
0x03 + ACK
0x1E + NAK
Setup Write to [0xEC] + ACK
0xF4 + ACK
Setup Read to [0xED] + ACK
0x00 + NAK
Setup Write to [0xEC] + ACK
0x01 + ACK
Setup Write to [0xEC] + ACK
0xF4 + ACK
Setup Read to [0xED] + ACK
0x00 + NAK
Setup Write to [0xEC] + ACK
0x00 + ACK
Setup Write to [0xEC] + ACK
0xF4 + ACK
Setup Read to [0xED] + ACK
0x00 + NAK
Setup Write to [0xEC] + ACK
0x54 + ACK
Setup Write to [0xEC] + ACK
0xF5 + ACK
Setup Read to [0xED] + ACK
0x00 + NAK
Setup Write to [0xEC] + ACK
0x30 + ACK
Setup Write to [0xEC] + ACK
0xF4 + ACK
Setup Read to [0xED] + ACK
0x00 + NAK
Setup Write to [0xEC] + ACK
0xF4 + ACK
Setup Read to [0xED] + ACK
0x00 + NAK
Setup Write to [0xEC] + ACK
0x01 + ACK
Setup Write to [0xEC] + ACK
0xF7 + ACK
Setup Read to [0xED] + ACK
0x80 + ACK
0x00 + ACK
0x00 + ACK
0x80 + ACK
0x00 + ACK
0x00 + ACK
0x80 + ACK
0x00 + NAK

And weird one is at Write to register F4 [BME280_PWR_CTRL_ADDR] now starting to be even more confused 😞

RE: BME280[I2C] return same values using TWIM

haakonsh — Thu, 10 Oct 2019 13:51:22 GMT

The members that points to the addresses that the TWI peripheral uses for the transactions need to be declared as volatile.

RE: BME280[I2C] return same values using TWIM

Nguyen Hoan Hoang — Thu, 10 Oct 2019 03:06:23 GMT

volatile is not for a struct. You are passing an address so volatile is not required neither. Try this driver here. It works with both SPI or I2C.

https://github.com/IOsonata/IOsonata/blob/master/src/sensors/tph_bme280.cpp

https://github.com/IOsonata/IOsonata/blob/master/ARM/Nordic/src/i2c_nrf5x.cpp

https://github.com/IOsonata/IOsonata/blob/master/exemples/sensor/env_tph_demo.cpp

RE: BME280[I2C] return same values using TWIM

InvalidException — Wed, 09 Oct 2019 18:34:42 GMT

If I declare it as volatile I get error 😞

error: passing argument 2 of 'bme280_get_sensor_data' discards 'volatile' qualifier from pointer target type [-Werror=discarded-qualifiers]
     rslt = bme280_get_sensor_data(BME280_ALL, &data, &bme280);

RE: BME280[I2C] return same values using TWIM

haakonsh — Wed, 09 Oct 2019 13:24:22 GMT

Then I bet the compiler optimizes out the actual reading of this register as it does not know that the TWI peripheral actually writes to the 'data' variable. Since this variable is never written to programmatically the compiler thinks the data it contains never actually changes and never bothers to actually read its value when using it in the sdk logger.

Declare it as volatile and report what happens :)

RE: BME280[I2C] return same values using TWIM

Mojo — Tue, 08 Oct 2019 21:36:05 GMT

use this library, it's much better. Has port for nRF5x series.

https://github.com/IOsonata/IOsonata

RE: BME280[I2C] return same values using TWIM

InvalidException — Tue, 08 Oct 2019 20:55:43 GMT

'data' is structure declared at top and it is not volatile

struct bme280_data data;

type can be read from bme280_defs.h#L300

Will try tonight/tomorrow to read directly from registers (instead of using Bosch library)

RE: BME280[I2C] return same values using TWIM

haakonsh — Tue, 08 Oct 2019 10:43:45 GMT

Is the variable 'data' declared as volatile?

What is the value of data if you inspect it with a debugger?