I modified the code from
https://github.com/sparkfun/SparkFun_Ed … ode0_dma.c
and
https://github.com/tensorflow/tensorflo … der.cc#L56
to sample the mic for an application similar to the tensorflow yes/no example.
It can recognize the specified wakeup word when it is powered by the USB connected to the PC.
But it fails to work when powered by a newly purchased coin battery (3V).
To make sure that my program is running, I let a LED blink periodically. And when the specified wakeup word is detected,
another LED is set to ON.
When it is battery powered, I can see the LED is blinking. But the board works only for less than 10 seconds.
That is, it can detect the wakeup word when it is first powered on. After 10 seconds, I can only see that the LED is blinking,
but the board does not respond to the wakeup word any longer, even if I press the reset button.
I am perfectly sure that my program works since it can detect the wakeup word when powered by USB.
I have a doubt that the ADC on the board does not work properly when the board is battery powered.
The blinking LED becomes darker when it is battery powered. Furthermore, I have measured the following voltage between VDD and GND on the board
(1) When it is powered by USB, it is 2.92 V.
(2) When it is powered by a 3V coin battery, it is only 2.20 V.
I have also tried the tensorflow yes/no example from
https://github.com/sparkfun/SparkFun_Ed … rflow_demo
The board can detect yes when it is powered by USB. But nothing happens when it is battery powered. No LED is blinking. That is, all LEDs are off. They only blink once when I press the reset button.
Is it normal that the ADC is not assumed to work when the board is battery powered? Or is there anything that I should do to fix the above problem?