MicroPython Forum (Archive)

Hi!

I own an Helios ventilation unit, which as very poor firmware. It is buggy, it has useless features, and missing important ones. More, the model I bought will never has a KNX gateway (unlike all other models)... And Helios support is inefficient, at least the french one.

So, I plan to re-write the firmware. But I don't have skills to develop in C (especially with STM32, which is much more complicated than AVR), and I would love to switch to micropython.

The electronic currently uses a LQFP100 STM32F103VBT6 chip. I had a look at the pinout, and it looks like it is really close to the LQFP100 STM32F405RG one! The only differences I found are :
So, the idea is to remove the F103 and solder a F405. What I will need to do is:

- reroute pin 19 to other VDD signals (if needed)
- keep pin 20 connected, as VREF- should be routed to VSS on previous board (need to check)
- reroute pin 49 and insert a 2,2µF capacitor (to ground)
- insert a capacitor on pin 73, as for pin 49

What do you think? Am I missing import points?

Then, micropython firmware part. I guess I will have to compile a new firmware, in order to support additionnal pin (original pyboard only uses a LQFP64 chip). Is it something easy to do, by changing/adding a few #define in the code? Or does it need to add some code to support additionnal timers/ADC and so?

Last: will it be possible to enable all alternate features to match the ones needed on the vent unit board? I dscribed them here:

https://www.logre.eu/wiki/Firmware_VMC_ ... 9sum.C3.A9

Thanks for your help.

PS : do you know a dev board using a LQFP100 STM32F405RG chip?

I looked at adapthing this: (which uses a '103) https://www.tindie.com/products/bobrici ... 2f103rbt6/

The board files are here: https://oshpark.com/shared_projects/2g2CvgcO I was thinking that using a 405 would make for a neat variant of a micropython board.

The STM32F4 Discovery board uses the '407 in a 100 pin package.

You can check https://github.com/micropython/micropyt ... 4xx-af.csv to see the functions available on each port/pin in the STM32F4 family and verify that one of the alternate functions matches each function you need.

Is it possible to choose the AFs from micropython, or does it need C-level mods?

Right now it needs C mods (in general). For functions which are currently supported in micropython (GPIO, ADC, I2C, SPI) the C side is already taken care of.

Actually, using stm.mem8/16/32 you can read/write any register, so in theory you could do it all from python.

I didn't know this feature! Nice