GPIO27 problem in Q2686H



We have detected a very strange problem.
GPIO27 is multiplexed with I2C, but we use it as a gpio.

When we set to Hi this GPIO the microphone stops to work, it doesn’t sound. It’s like setting mute ON.
There is not any external connection between both signals.

We asked it to our distributor, and she says that maybe the pin cannot be used as a gpio. Is it possible? is it truth?
We haven’t found any documentation about it, and we are very confused…

Any idea about this problem?

Thanks, Alex


GPIO27 is listed as Open drain I/O type that is muxed with SDA (I2C).

What firmware do you have this problem with?


Hi tobias,

I’m using Q2686H working on Open At OS v4.21.01; firmware version 663_09gg.

Thnaks, Alex


It could very well be a bug or “feature” in the firmware…

Could you describe how you test this?


Yes, I will try to explain you what we do.

We have GPIO 27 as a enable pin for turn on/off a external Bluetooth chip using a pull-up resistor to set it to high level.
The microphone is connected to MIC2P and MIC2N using direct wires, without any external elements.

If we are with a established call, when we set GPIO27 Hi then speaker continues working but microphone stops. It seems as MUTE was set ON.

There aren’t any interference problems between both elements. We can’t find any connection between GPIO27 and MIC2 pins.

Any idea?


If you’re certain that the I/O is free for use before subscribing to it, I can only suggest you write down as much as possible about the problem and get your distributor to forward it to Wavecom. It may be hard to convince them that there is a problem with the firmware, but keep pushing if it’s important for you to use that I/O.
As a workaround, look for other I/O’s to try with.


Thanks tobias,

We asked it to our distributor on tuesday without any clear response yet…they said they would ask it to Wavecom…
So we only can insist with it.


atcaeiro, Did you figure this issue out? I’m also seeing similar problems with GPIO 26 and 27?



No advance. Wavecom said us, to resolve it by breaking the wire which connect it, but it is not a solution for us.