microspecgui 0.0.1a8

Chromation spectrometer dev-kit GUI

Install

$ pip install microspecgui

This installs:

• pygame: Python interface for SDL (Simple DirectMedia Layer), a highly portable library for low-level access to graphics hardware and input devices (keyboard/mouse/joystick)
• pygstuff: helpers to simplify pygame applications
• microspeclib: Chromation's spectrometer dev-kit API

Run

Connect the Chromation spectrometer dev-kit, then:

$ microspec-gui

Keyboard Controls

q   - quit
a   - auto-expose (spacebar works also)
x   - decrease exposure time
X   - increase exposure time
h/l - navigate wavelength slow
j/k - navigate wavelength fast
0   - go to shortest wavelength
$   - go to longest wavelength

Joystick Controls

BACK - quit
A    - auto-expose
X    - decrease exposure
Y    - increase exposure
right-stick   - navigate wavelength slow
left-stick    - navigate wavelength fast
left-trigger  - go to shortest wavelength
right-trigger - go to longest wavelength

Platform compatibility

Developed on Windows using Python3.8 and pygame 1.9.6. Tested on:

• Windows 8
• Windows 10
• Linux Mint 19.3
• Raspberry Pi OS Lite on:
  • Raspberry Pi v1.2 Model B+ 512MB (2014) -- GUI is slow
  • Raspberry Pi 3 Model B+ (2017) -- GUI is good (like the desktops)

Trouble installing pygame on Linux

Windows installs the pygame package with no trouble, but Debian distributions (e.g., Linux Mint and Raspberry Pi OS) are usually missing SDL build dependencies and are therefore unable to run pygame out of the box. For example, on Raspberry Pi OS Lite, I get this error when attempting to pip install pygame (or when attempting to install microspecgui, which in turn installs pygame):

ImportError: libSDL-1.2.so.0: cannot open shared object file: No such file or directory

This is easy to fix. There are two steps: update the package manager with source distributions, then install the pygame build-dependencies.

Configure the source list

First, if you have never built anything from source on your Linux system, you need to configure your package manager source list with deb-src URLs.

The sources.list file usually has both deb URLs and deb-src URLs, but the deb-src ones are commented out. The package manager needs these sources for installing build dependencies.

Open /etc/apt/sources.list and find the lines starting with deb-src that are commented out. Uncomment these lines.

sources.list is a protected file, so you will need to prefix your text editor command with sudo.

sudo vi /etc/apt/sources.list

For example, my Linux Mint /etc/apt/sources.list has this line:

# deb-src http://archive.ubuntu.com/ubuntu bionic-updates/main amd64 Packages

I remove the comment:

deb-src http://archive.ubuntu.com/ubuntu bionic-updates/main amd64 Packages

Similarly, on Raspberry Pi OS Lite, there is only one line starting with # deb-src. Uncomment by erasing the # symbol, and save the file.

Update the package manager with the new sources

Now do apt update or apt-get update to update the newly configured sources.

sudo apt update

Install SDL dependencies

Now install the SDL build dependencies:

sudo apt-get build-dep python-pygame

Note this does not install the python-pygame package, but installs the dependencies for that package, which is exactly what's needed to pip install pygame.

Install microspecgui

Now finally microspecgui will install with the usual command:

$ pip install microspecgui

Build from source

Unrelated to using pygame or microspecgui, your Debian system is now empowered to build projects from source, for example:

sudo apt-get build-dep vim # powerful text editor

This only installs the necessary build dependencies. To actually install Vim, clone the official repository and follow the instructions to run the configure and build scripts.

Installing software with sudo apt install is much faster than building from source. But often, the Debian version is considerably older than the latest stable version.

For example, at the time of this writing, I ran into this with both Python and Vim, where the available Debian versions were considerably older and missing features I relied on. When this happens, I build from source.

Trouble running the GUI because it does not see the dev-kit

If the GUI cannot see the dev-kit it is a setup problem with USB. Windows and Linux each have their own USB setup.

Enable VCP driver on Windows

The dev-kit uses FTDI# FT221X for USB communication. You should not need to download drivers from the FTDI site, but you do need to tell Windows to Load VCP for this device.

This setup only has to be done once for the dev-kit, but if you are using more than one dev-kit you need to do it for each one.

• open Device Manager
• locate USB Serial Converter, right-click and select Properties
• on the Advanced tab, check the box to Load VCP

Grant USB permission On Linux Mint

If this user is communicating with an FTDI device over USB for the first time, you probably need to add this user to the dialout group. This grants the user permission to communicate with the dev-kit over USB.

This setup only has to be done once for the dev-kit. If you are using more than one dev-kit, you do not need to do this setup again.

Check hardware is visible

• connect the dev-kit with a USB cable
  • expect: dev-kit indicator LEDs light up
  • two yellow LEDs
  • three green LEDs
• display messages from the kernel ring buffer that contain string FTDI:

$ dmesg | grep FTDI
[101038.609497] usb 3-1: FTDI USB Serial Device converter now attached to ttyUSB0

Check if the current user is part of the dialout group:

$ groups $USER | grep dialout

If the user is already part of dialout, a list of groups is printed and dialout is highlighted.

If the user is not part of dialout, nothing is printed.

Add this user to dialout:

$ sudo adduser $USER dialout

Confirm the user is part of the dialout group:

$ groups $USER | grep dialout

Finally, logout and log back in (or simply restart the computer). Even though the user is listed as a member of dialout, this change does not take effect until the user logs back in.