Arduino for STM32

@ fpiSTM
I have examined the two header files, STM32RTC.h and rtc.h (and the cpp file) but I cannot find any info on reserved bu ram use.
Do you know which ram locations are used, or where they might be declared.
Best Regards
picclock

I am using STM32RTC arduino library, stm32f401, with battery powered backup registers (20x32bit).
Do the rtc registers, (hour, min day etc.) affect or use any of the backup register space ?.
I intend to use the internal rc clock as accuracy is fairly unimportant.

Any help much appreciated.

Best ...

@fpiSTM
Thanks for the link, much appreciated. It will take me more than a minute or two to get around that.

From a quick scan this looks like the simplest option :

Serial.setRx(PA10); // using pin name
Serial.setTx(PA9);
Serial.begin(9600);

Just checked it out and it works a charm ...

I'm using ST Link V2 for programming and an ftdi serial adapter connected to PA9, PA10 on an stm32F401.
This works fine for serial print of data to the Arduino serial monitor.

However I cannot get it to input characters, as the serial event function is not called.

Using the example serial event ...

ag123
Thanks for the info. I had realised after further reading that I can only access the 80bytes (20 words) of the rtc area. 80 bytes is pushing it for my storage needs but I think its possible with a bit of careful programming (fudging ;) ), converting the 32 bit words to 8/16 bit integers and ...

@ag123 This solution resulted in an unrecognised F401, which I recovered using STLINK V2 and releasing the reset whilst pressing connect on the Cube programmer.

Reading more info I have discovered that this chip has 2k of battery backed up RAM. This seems like a simpler approach and requires only a ...

fpiSTM wrote: Thu Nov 04, 2021 10:30 am Try the builtin EEPROM library

I thought I was onto a winner when EEProm.size reported 16384, but trying to write or put anything crashes the code. Can read lots of ff's though

Will try ag123 solution.

Many Thanks

picclock

@GonzoG
Thanks for the clarification, the datasheet was a bit ambiguous about that ( at least to me ).
I can live with a 16k block, and 10k erase write cycles is plenty for my purpose.

So any info on how to implement this much appreciated

Best Regards

picclock

I'm trying to get this to work, but there does not seem to be a library which is compatible (FlashStorage_STM32F1 will not work with 32F401).
I need about 100 bytes or so of EEProm memory, or flash memory which can be written to under program control. 401 has 256k which seems to be in a large chunk ...

Thankyou for that post. It saved the day , and possibly my sanity.

for the first time I have a fully functioning SDFat on SPI2.

Definitely worth a virtual Beer !!!

Best Regards

picclock