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Scanning and Capture Card

A project log for My Custom Scanning Electron Microscope

This is a scanning electron microscope I am building from scratch from mechanical, electronics and control software.

vinis-labVini's Lab 02/28/2022 at 16:540 Comments

Currently I am working in the Scanning / Capture card.

The scanning and signal capture must be synchronized with each other so they had to be placed in the same card. 

The synchronization between DAC and ADC capture happens using the Pi Pico PIO.

It is an amazing peripheral, it can substitute a FPGA in many tasks.

To be able to send data to the computer in high speed I will use the FTDI chip capable of operating in USB 3 mode so I will be able to achieve good resolution at reasonable frame rates operating the instrument in video mode.

The schematic is far from done, I mostly worked on the ADC schematic so far, I will be able to sample 4 channels continuously so multiple detectors can have their data displayed in layers in the software at the same time.

The ADC will expect a signal 0 - 5V on it's buffered inputs coming from the sensors preamp boards.

I will use this acquisition board on future projects as well, so I am making it as general purpose as possible.

I am using a PCIe1X connector to interconnect with my backplane for powering and USB connection.

The backplane will contain a USB hub which will be connected to the host computer.

This is a preview how the PCB layout is going on.

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