Raspberry Pi HQ microscope

Current work in progress. Feel free to contribute 😉

Raspberry Pi HQ microscope

Preface

A small project to build a custom electro microscope based on a Raspberr Pi 3A+ and Raspberry HQ camera. But why a 3A+? Because of current delivery problems. The 3A+ has also a normal HDMI port and not such an fiddly diddly micro hdmi port 😜 Also the form factor and the geekworm case is a good choice. In fact that it based on a Raspberry Pi it can be modified in any direction.

PCB adapter or mount between RPI 3A+ and RPI HQ camera

The pcb acts as mounting adapter between the Raspberry Pi 3A+ and the Raspberry Pi HQ Camera. It has also 5 buttons that can be used to add custom functions with python.

PCB images

Front	Back

Available buttons

Button	GPIO	Function
1	17	select mode/option
2	27	increase option value
3	22	decrease option value
4	19	capture photo
5	26	shutdown raspi

BOM

Part	Quantity	Description
	1	Raspberry Pi 3A+
	1	Geekworm Raspberry pi case
	1	Raspberry Pi HQ camera
	1	camera cable 6 cm
	1	180x zoom objective with c-mount
	1	0.5x barlow lens
	1	LED ring light
	1	Heavy duty stand
	1 (optional)	HDMI 90° adapter
	1 (optional)	spacer for the heavy duty stand
	1 (optional)	USB Wifi dongle (optional for "better" wifi connectivity)
	1 (optional)	pcb (optional. depending to your needs.)
	1 (optional)	header femal 2x20 pin (optional. depending to your needs.)
	5 (optional)	push button 6x6 (optional. depending to your needs.)

Software

SD Card

Prepare Sd-Card with Raspberry Pi OS Lite 32 bit image as usual described in a lot of places in web with balenaEtcher or similar tool. 64 bit version of Raspberry Pi OS is not working because needed libmmal is not available for aarch64.

Install needed packages

sudo apt install python3-pip
sudo apt install python3-picamera

pip install picamera

Cronjobs

Starting needed software with crontab on boot. Can vary depending to custom needs. Use crontab -e to edit the cron jobs.

# start simple preview to hdmi output
#@reboot libcamera-still -t 0 --width 1920 --height 1080 --rotation 180 -o current.jpg

# start python script. path to user home can vary in your case
#@reboot sudo python /home/micro/shutdown.py
@reboot sudo python /home/micro/advanced.pyq

list running cronjobs

pstree -apl `pidof cron`

or 

ps aux |grep "/home/micro/advanced.py"

or

ps -o pid,sess,cmd afx | egrep -A20 "( |/)cron( -f)?$"

stop running cronjonb process

# stopping process
pkill -s [pid]

#example
pkill -s 424

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