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1st board assembled

A project log for STM32F4inputs

An STM32F4 circuit board with emphasis on analog input

esben-rosselesben rossel 06/16/2018 at 05:440 Comments

the title says everything.

I had some difficulties hitting the right combination of resistors for the opamp. I guess Vref in the opamp circuit should have come from a voltage reference rather a simple voltage divider, and also I should have paid more attention to and money for the resistors in the PSU-section as ±4.65 is more like + 4.660V / -4.365V.

But everything turned out well in the end. Output from the CCD now looks like this:

rather than this:

Improvements in noise is probably from setting the scope to 12-bits instead of 10, but the interesting part is that the output for zero light is 145mV, and a full saturation is 3.23 V. Fairly close to the boundaries of the ADC's range.

Next up is porting the firmware for the STM32F401 to the STM32F405 and redirecting communication to USB. The first part willl be easy, I'm less certain about the USB-part, but I've completed the first step: Getting the MCU recognized as virtual com port (ttyACM) on my laptop.

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