Arduino for STM32

As I said, I'm no Arm assembly expert, but I'm always willing to learn...

Given you can see in the assembly listing that the ldrh instructions are only 2 bytes, and it must have space to identify the instruction (op code of some sort), and two registers, there can't be very many bits to use for the ...

Also, the attribute volatile will / might change the compiler code generator. I will check this out.
...
Now, arm assembler is not really my thing, I grew up with the pdp11.


Well, I can't see anything at all in the fragment of assembly code that you showed that would be moving data to the GPIO ...

...
------- C code -----------

for(k=0;k<maxdata;k++) { // fill array with alternating 0 and 1
if(( k & 1) == 0)
datarray[k] = 0x0;
else
datarray[k] = 0xffff;
}

t1 = micros(); // this does not serve any purpose now, it just generates a bl micros, which is easily found in the dump file ...

...
I cannot see any good way to unroll the loop since I need to change the array index, but I have to study ARM assmbler,
The ldrh.w and the strh could be replicated, but R7 needs to change.....+2 i guesss...

ldrh.w r1,[r7],#2
strh r1,[r2,#12]
adds r7,#2

this should be 4 instructions per move ...

CTRL : 40000000
CYCCNT : 40000000
80
0
------------------------------------------
Then I add the cycle counter enable, CYCCNT does not change.
-----------------------------------------
CTRL : 40000000
CYCCNT : 40000000
CYCCNT : 40000000
80
0
-------------------------------------



0x40000000 ...

1073741824 = 0x40000000 which looks like a plausible reset value for CTRL, so is that DWT_CTRL (at 0xE0001000) or DWT_CYCCNT (at 0xE0001004) that you are showing there?

If that is really CYCCNT, what is in CTRL? That could indicate if the cycle counter is truly not implemented, or maybe (more ...

The manual I was looking at before was just what Uncle Google turned up. From the page mentioned here by ag123, https://www.arterychip.com/en/product/AT32F403A.jsp, I find another manual, which says it is V2.03. The clock tree in this manual shows the 120MHz is multiplied by one or two, so 240MHz ...

Does this processor really not have a cycle counter?

The manual I turned up, https://www.arterytek.com/download/RM_AT32F403_V1.02_EN.pdf, mentions DWT in several places, and I would have thought DWT would include DWT_CYCCNT.

But then, that manual I found mentions CPU operating up to 200MHz, not ...

The serial protocol is described here: http://www.st.com/web/en/resource/techn ... 264342.pdf

I'm not sure if anybody has written exactly what you need. If not, you could maybe use something like this as a starting point: https://sourceforge.net/projects/stm32flash/

How do I display the generated assembly code?


If you were using an ide which allows debugging, it would probably allow you to just select assembly view.

Otherwise use arm-none-eabi-objdump.exe -D your.ino.elf

Setting the compile options to verbose in the Arduino ide preferences will help you ...