Arduino for STM32

Thanks again. Yes, I disabled the UART and everything works the same and that freed up a little more flash:

Sketch uses 58964 bytes (89%) of program storage space. Maximum is 65536 bytes.
Global variables use 4192 bytes (20%) of dynamic memory, leaving 16288 bytes for local variables. Maximum is ...

Here's my current settings that have working reliably although I've only flashed a handful of times since getting this to work

When I was experimenting with the USB Boot Loader I never did get it work without some type of manual reset but the HID has always worked to reset the board automatically.

I did a little poking around on the internet to see if there was a different way to determine if you indeed had extra flash but I didn't see anything. You're correct though that it definitely isn't a reliable solution to buy C8 parts and expect them to be CB unless ST is using the same die and just ...

fpiSTM wrote: Thu Jul 16, 2020 10:01 pm Ok, so without USB CDC

Correct, at least for now I'm using the HID since it seems to work well

No, I just flashed my board and it is working using the HID bootloader. In my previous post I showed that it fits and is "only" using 92% of the flash space. I didn't make any changes to the sketch and I am also enabling the Serial port.

@fpiSTM Thank you for providing all the details, I will study it. I know that the libraries are not optimized and I am also using fonts but lucky for me I showed in the last post that using the HID boot loader did seem to work and even leave bit of flash left.

Well I decided to give HID a try and it seems to have worked. I used the ST-LINK uploader tool to load the HID boot loader. The I enabled the serial port again, chose Generic F103C8 as my board and used the Arduino IDE to flash the board.

For reference, here's the console output:
Sketch uses 60712 ...

Looking at the HID boot loader it seems that I just need to download the file and I can load it using ST-Link over SWD. Then I just change the upload method from Maple DFU to HID and that's it? Did I miss anything?

It's at least worth a try to see if that works.

Yes, the F405 would be a good solution but it comes at a price of course! So I'm hoping this can work with the F103C8.

So are you saying that even if the part is marked as a C8 and it reports to be a C8 with 64k flash it still might actually have the full 128k flash?

Is there are harm in setting ...

Attached is my sketch. I started development on a STM32F405 Feather from Adafruit but my program was compiling well under 64k so I thought it was safe to drop down to a STM32F103C8 and save some money.

The code is a bit ugly and I haven't tried to trim it at all but from the tests we've run today ...