RoseOnRails – Python… and ledstrip testing


Today, I continued “playing” a bit with PyCharm trying to get used to Python. Then I wrote a small program that does the client role in a TCP socket connection with my C program where I have implemented the server part. Now I can send the commands through the Python client and see the results on the nrf Eval Kit board (by writing values in the characteristic of an LED in the BLE app running on the nrf).

Unfortunatey, I couldn’t go further in this since we had to test the “pieces” of ledstrip we had soldered. The thing is that this turned out to be waaaay longer and tougher than I thought. In fact, while some ledstrips were perfectly functional (we tested them with a program sending random RGB values to the LEDs in loop, through the stm32f2103’s SPI bus). However, on some others, we observed total random behavior: for instance, some LEDs blinked on the first pieces of the ledstrip, and then the rest of the LEDs were off, or sometimes, all LEDs blinked except one or two! Sometimes, this was due to our soldering (some pieces of wire weren’t well soldered, or sometimes some wires touched…), in which case we resoldered them correctly. But the most disconcerting situtations were those where we had made sure all connections were ok (with the multimeter) but still, some LEDs were off for no obvious reason! Several ideas came into our mind: maybe we had damaged some LEDs in a way that we had changed their electrical characteristics (typically the required voltage for a high state for instance), maybe the voltage drop by the LEDs was too important, in  way that the first LEDs blinked correctly whereas from a certain position on, the voltage was not necessary for the other LEDs to blink anymore, maybe the voltage provided at the SPI output of our mircontroller is too low (3,658 according to our measures with the oscilloscope) compared to what is specififed as the minimum voltage required for a high state for the LEDs…. we discussed about this also with ph and Félix and they gave us some ideas, encouraging us before all to check the voltage drop of the LEDs on some pieces of our ledstrips, as well as check the output voltage of the SPI. It was unfortunaly a bit late (midnight..) to carry out the tests so we will have continue tomorrow. I strongly hope we will solve this “problem” soon, since we have a lot of work to do on the software part too!

See you soon.



2 comments to RoseOnRails – Python… and ledstrip testing

  • Félix Raimundo

    If you are still working on sockets you might be interested in rabbitMQ (, it’s what we used in the PAF project and allows you to use sockets extremely simply (I managed to have a working stuff in less than a day) and in the language of your choice. What’s more it is incredibly well explained on their website 🙂

  • valeh

    Thanks I’ll have a look 🙂