RoseOnRails – ble and ledstrip on stm32f103

Hello all.

Today, I worked on the application I had started to code yesterday (the server app that listens for incoming connections from users, creates sockets to serve their commands, and (dis)connects and write to BLE devices characteristics upon request of users). I implemented the writing part, tested on different machines, and with several boards.It worked fine.

Then I started to code the thread responsible for receving notifications from the devices. The thing is that by doing fork() I could handle several connections with BlueLib (since forking makes two separate processes and not threads, so the memory is not shared). However, by creating threads, I had a BlueLib error telling me that a I couldn’t establish more than two connections (if I got it well, it’s because threads share the same memory and BlueLib contains global variables that are therefore common to all threads (furthermore, BlueLib itself deals with 2 threads..!) so in short, it’s not possible to have two connections since the two threads would have to share the same memory resources). Yann suggested we could do several fork()s, so several processes, to deal with the multislave connection. But since we saw Hubert in the afternoon we decided to talk directly to him about it. He explained how BlueLib worked to us and how we should do to implement the multisalve functionality… but it seemed “a bit” difficult to implement staright away. So he said he would have a look at it and do some improvements and let us know about what he’ll have done. I guess I’ll try the fork() just to see if it works, but I’ll ask Sam’s advice before… I’ll see this tomorrow.

Then I started working with a stm32f103cb (the board ROSE students used last year) since we’ll be using a stm32f103re processor (and not a stm32f407 anymore). I spent quite a long time re-configuring the SPI on it and doing the right connections… fortunately, I managed to light up the leds once again. Then I tried to assemble several led strips (10 on one SPI) to see if we had enough power (and memory for the buffer stocking the bits to send through SPI) to control them all.

Unfortuntely, it was fine up tp 8 ribbons (of 30 LEDs) but then I started to have ram overflow errors. Checking the datasheets, I figured out that we might have some memroy problems since the buffer will become too big with 30 ribbons of 30 LEDs each to control. I’m not sure yet, maybe I did the calcualtions wrong since I’m a bit tried right now, but I’m really worried about this and I guess first thing I’ll do tomorrow is to think about it and determine if yes or no we will have enough memory for our buffer…

That’s about it for now. See you soon!


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