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Espruino is a JavaScript interpreter for low-power Microcontrollers. This site is both a support community for Espruino and a place to share what you are working on.
@Olivierp
It works. I found out how a "pulldown resistor" would solve the noise problem, and a with a bit of testing I was able to generate the 40khz pwm and record it in a 4096 bytes waveform at 20khz.
Here is a photo of the nokia LCD on which I visualize the result.
The Chirp duration was 100ms, during which 4 spikes were recorded.
I will try to record the signal with my raspberrypi, maybe it can handle a higher frequency.
Now one of the issue I have left is the 3.3V. Is there a way - of course with an external source of power - to have the 40khz PWM at twice or thrice the voltage?
With some googling I found circuits such as:
MAX756 or LT1073
The MAX757 spec specifies an "Oper. Freq." of 500kHz. Does this mean that If I provide it with a 40khz PWMed 3.3V from the espruino it will deliver a 40khz square signal at 5.0V ?
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