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…
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.
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.