Arduino Forum

Products => MKR Boards => MKRGSM1400 => Topic started by: alexduch on Dec 16, 2018, 12:49 pm

Title: Board doesn't boot when SDA pin is not in tri-state
Post by: alexduch on Dec 16, 2018, 12:49 pm
Hi,

I used I2C feature to communicate with an other board (SDA, SDL, GND pins connected).

When power up the boards, I noticed that I have to force SDA, SDL pins from my other board in high impedance, otherwise the MKR board remains in an undefined state (program is not started, and CHRG led blinks quickly).

Let me know if you have the same be behaviour with your MKR board (you can simply connect SDL pin to GND)?


Is it an hardware bug?
Title: Re: Board doesn't boot when SDA pin is not in tri-state
Post by: sandeepmistry on Dec 17, 2018, 03:12 pm
Hi @alexduch,

There is a PMIC connected to the I2C ports of the board. When the board boots, the boot loader tries to put  it to a "safe" configuration for charging.
Title: Re: Board doesn't boot when SDA pin is not in tri-state
Post by: alexduch on Dec 17, 2018, 07:30 pm
Hi @sandeepmistry,


Quote
There is a PMIC connected to the I2C ports of the board. When the board boots, the boot loader tries to put  it to a "safe" configuration for charging.
What is the good practise to use I2C without to be stuck in the "safe" configuration?
I put a delay on the second board (pins in tri-state) before the MKR boot is done but It is not really a "clean" solution.

Finally, I have configured an other I2C (on pin 0&1) and I don't have the problem with these pins.