Arduino Laser Controller updated to v2!

I had a little bit of free time, so the time came to revisit an old project, the thorlabs-ldc-arduino. [panel] [GUI]. The plan is to include a second Thorlabs Laser Driver, the LDC500.

Laboratory upgrades

We bought a OSRAM 450nm laser diode from ebay, and installed it into a TCLDM9 head paired with an LDC500 driver. The old problem came up, that the laser driver is super, but it cannot communicate with the PC. I grabbed these images from the internet, to describe the problem:

Only two BNC connectors, one for setting laser current, the other is for checking the laser current.

Panel upgrades

The custom shield had to be updated:

  1. A BNC splitter is used to duplicate the MOD In.
  2. A new BNC connector is added (ADC-CTL OUT)

Code upgrades

The arduino and labview code can be found on github.

Arduino Changes:

  • Merged the the DHT branch with the master branch: I marked the parts which need to be commented out in case there is no DHT22 sensor an library.
  • Updated the code to include a second laser in read only mode. The read commands are incremented by one letter: [j? q? qa?]
  • Adjusted the linear coefficients to work better with two lasers.

Labview GUI Changes:

  • Labview 2014 version (no changes here).
  • Stripped the previous code from the Cobolt subVIs.
  • Introduced an initial delay, because there has to be a wait after the arduino is reset.
  • Replaced the setPower actuator to a setCurrent actuator.
  • Shortened some delays.

Known limitations

As the LDC500 does not have an ON/OFF input, when both controllers are turned on, both of them ar controlled at the same time (BNC slpitter). To overcome this, the user can switch off the LDC205 controller with the ON/OFF button on the GUI and control only the LDC500 driver. Or the user can turn off the LDC500 controller with the power button on the driver and it won’t interfere with the reactivation.

Note: We don’t use the two lasers at the same time, so for us it is not a problem.


Raspberry Pi A+ with internet

Recently I got my Raspberry Pi 1 A+ and camera from Farnell. As I wanted it to be small (it will be in a case) the cheaper “A” version was a better than “B” for me. The three major differences between A and B version are the following:

  • only 256 Mb Ram
  • only 1 USB (but it is full 2.0)
  • no ethernet connector

A connection to the local subnet will be mandatory, as I want to replicate this bird cam project. So I had to figure out, how to connect my Pi to the router, and also how to keep the price low. This usually means higher hack coefficient. I came up with three solutions, and at the moment two of them all three is working. These are not my work, (I only searched and tested them) they are only put together here for make life easier for those who walk in the same shoe…

Continue reading “Raspberry Pi A+ with internet”