Difference between smt32 black pill and blue pill reading i2c sensor gy-91

maxgerhardt · May 11, 2021, 2:59pm

Interesting. The other library does the same type of checks

bolderflight/invensense-imu/blob/930e2ed8c42aba557d679e2983759b651d6b2209/src/mpu9250/mpu9250.cc#L151-L173


      
          /* Check the WHO AM I byte */
          who_am_i_;
          if (!ReadRegisters(WHOAMI_, sizeof(who_am_i_), &who_am_i_)) {
            return false;
          }
          if ((who_am_i_ != WHOAMI_MPU9250_) && (who_am_i_ != WHOAMI_MPU9255_)) {
            return false;
          }
          /* Enable I2C master mode */
          if (!WriteRegister(USER_CTRL_, I2C_MST_EN_)) {
            return false;
          }
          /* Set the I2C bus speed to 400 kHz */
          if (!WriteRegister(I2C_MST_CTRL_, I2C_MST_CLK_)) {
            return false;
          }
          /* Check the AK8963 WHOAMI */
          if (!ReadAk8963Registers(AK8963_WHOAMI_, sizeof(who_am_i_), &who_am_i_)) {
            return false;
          }

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but definitely does different I2C writes – the hideakitai library directly reads the AK8963_WHOAMI register, the bolderflight library sets up a few internal I2C registers first, it seems…

In any case I think if you create an issue in Issues · hideakitai/MPU9250 · GitHub for the I2C ERROR CODE : 3 that is thrown on your GY-91 module, that we good, any maybe something can be fixed.

That doesn’t solve the problem on the F4 though, where none of the two libraries work…

I also see that GitHub - bolderflight/invensense-imu: Arduino and CMake library for communicating with the InvenSense MPU-6500, MPU-9250 and MPU-9255 nine-axis IMUs. is quite active with a commit 3 days ago. You should also try and open a github issue and see if you can get that library to work.