Mpu9250 does not work with ESP32 1.0.0 release (latest) about sparkfun_mpu-9250-dmp_arduino_library HOT 4 CLOSED

It appears this is a problem in the ESP32 i2c arduino software. The board works with the 1.0.0-rc3 release but everything newer fails.

from sparkfun_mpu-9250-dmp_arduino_library.

Over on the ESP32 github here espressif/arduino-esp32#1761

They suggested a fix which I tried, but most samples still only work intermittently. They often work from a cold start but pressing the reset button they will only sometimes start. After 3 or so presses they generally fail to come up until cold started again.

Some samples still seem to fail 100% of the time.

Could this be a timing issue of some kind because the ESP32 is a faster chip? Maybe the 9250 is not getting enough time to reset and get itself started?

from sparkfun_mpu-9250-dmp_arduino_library.

Some more info, take a look at espressif/arduino-esp32#1761 for more details.

It appears the 9250 is getting into a state where it pulls sda low and leaves scl high. Resetting the ESP doesn't clear this. As long as the 9250 has power it stays stuck this way, only cycling power fixes it.

Is there any way to do a hardware reset of the 9250? When it gets into this state you can't communicate with it so a software reset isn't possible.

from sparkfun_mpu-9250-dmp_arduino_library.

It appears the problem has to do with resetting the CPU when the 9250 is in a particular state. The transaction doesn't complete and leaves the 9250 holding the bus with SDA low and SCL high.

Some new code has been added to the ESP32 repository to cause the I2C bus to recover if it comes up in a bad state after a boot. This code will be in the next release or you can get it now by updating to the latest ESP32 arduino code.

Seems to fix the problem so I'm closing this.

from sparkfun_mpu-9250-dmp_arduino_library.