Problems with I2C-Connection on MPU9250-Breakout-Board

Dear drotek,

my company has ordered a few samples of your MPU9250-breakout-board and we experienced quite alot of difficulties getting an i2c-connection established properly.

Our hardware-setup has a standard uart, a csr1010-btle-chip with battery-holder and a connector for an external power supply. The MPU9250-breakout-board is attached through a pin-bracket to the base-board.

We made numerous attempts testing the boards with/without soldering the pull up pads, with no pulls/weak pull up & strong pull up on software-side and different voltages from 3.3 to 5 V.

Apperently the only setup we got to work, was without soldering the pull up pads, a strong pull up on software side and 5 V power. Trying the setup with a lower voltage, resulted in a “no pull down”-effect for the clock-signal of the i2c-scl. The same result happened for the described soldered pull pads, no software-side pull up and voltages vom 3.3 to 5 V.

In a separate test we tried a gy521-breakout-board for the mpu6050, which worked smoothly even with battery at 3 V and weak-pull-up on software side. The problem seems to be the different dimensioning of the resistors for i2c-sda and i2c-scl. While the gy521-board works with 4.7k-resistors your board seems to use 10k-resistors making it difficult to operate at any voltage below 5 V.

Could you provide us with a how-to-tutorial on what options we have to consider in order to get i2c-connection established? Would be realy great if we could get it running even at 3.3 V.

Looking forward to your response!

Kind Regards
Ray

Hello,

We test our IMUs with Arduino board and that works fine with the pull up.

Dear drotek,

well that seems to explain the different experiences, since the Arduino-Boards most likely operate with 5V so there is always enough power.

We have to search for a new hardware then.

Regards
Ray