Search found 91 matches

by chuckbook
Mon Jan 23, 2017 8:16 pm
Forum: MicroPython pyboard
Topic: RTC oddity: has anyone seen this?
Replies: 5
Views: 2062

Re: RTC oddity: has anyone seen this?

If RTC detects a working LSE configuration it will keep it as long as Vbat (STM32F4xx) stays above a certain level (might be as low a 1V). If for one reason the LSE is halted (and it is quite easy to halt it while modifying HW), no attempt will be made to reanimate the oscillator. Currently the only...
by chuckbook
Mon Apr 11, 2016 8:15 am
Forum: General Discussion and Questions
Topic: How to reduce the memory consumption of the object definition
Replies: 25
Views: 7894

Re: How to reduce the memory consumption of that objet definition

This is obviously a font description (at least 96 printable chars).
If the char matrix is 14x13 ~2184 bytes are needed to encode a full pattern font in a simple array.
A directory encoded array of 16 bit words will need 650 values.
by chuckbook
Thu Mar 10, 2016 8:11 pm
Forum: MicroPython pyboard
Topic: RTC does not start?
Replies: 9
Views: 3860

Re: RTC does not start?

What is the output of rtc.info()?
After a full power cycle, including Vbat. Best to leave the board un-powered for a reasonable amount of time (1..2 minutes).
by chuckbook
Wed Mar 09, 2016 11:11 am
Forum: General Discussion and Questions
Topic: timer callback performance help
Replies: 9
Views: 2879

Re: timer callback performance help

It might be a good idea to lift timer int to highest priority as systick currently uses top priority.
Also timer 5 has slightly more overhead than timer 2.
Further improvement would require a mod of MPY to circumvent timer int dispatching.
by chuckbook
Tue Feb 09, 2016 10:27 am
Forum: General Discussion and Questions
Topic: Pin Toggle Frequency Contest against C. Please Help! :)
Replies: 41
Views: 12614

Re: Pin Toggle Frequency Contest against C. Please Help! :)

@pythoncoder the API changed recently. Try this:

Code: Select all

odr = ptr16(bytearray_at(GPIOA + GPIO_ODR,0x100))
@Roberthh don't waste your time, searching for lost cycles. On F405 there exists a memory bottleneck when executing from SRAM (which is the case for MPY). That's where the cycles get lost.
by chuckbook
Sat Feb 06, 2016 10:35 am
Forum: General Discussion and Questions
Topic: Pin Toggle Frequency Contest against C. Please Help! :)
Replies: 41
Views: 12614

Re: Pin Toggle Frequency Contest against C. Please Help! :)

I had a closer look at this. Brief results are: - The 21MHz toggle frequency is feasible (given C-code) but only if code is executed from flash. - 84MHz toggling is also possible (with loop unroll) when executing from flash, 42Mhz executing from RAM. - Having the cbxx opcodes in @micropython.asm_thu...
by chuckbook
Wed Feb 03, 2016 9:52 pm
Forum: General Discussion and Questions
Topic: Pin Toggle Frequency Contest against C. Please Help! :)
Replies: 41
Views: 12614

Re: Pin Toggle Frequency Contest against C. Please Help! :)

@dhylands, just out of curiosity. Did you try the asm test on a STM32F7xx board? I got 72MHz on PA13 at 216 MHz core freq.
Can you confirm that? Thanks!
by chuckbook
Wed Feb 03, 2016 12:00 pm
Forum: General Discussion and Questions
Topic: Pin Toggle Frequency Contest against C. Please Help! :)
Replies: 41
Views: 12614

Re: Pin Toggle Frequency Contest against C. Please Help! :)

Yes, the cb?? will allow a more balanced pipeline. Without this instruction 14 cycles (12MHz) can be achieved.
I'm still curious about the 21MHz. If that's doable I would like to know.
by chuckbook
Tue Feb 02, 2016 10:54 pm
Forum: General Discussion and Questions
Topic: Pin Toggle Frequency Contest against C. Please Help! :)
Replies: 41
Views: 12614

Re: Pin Toggle Frequency Contest against C. Please Help! :)

Hi Dave,
what about the timer int flag?
by chuckbook
Tue Feb 02, 2016 10:31 pm
Forum: MicroPython pyboard
Topic: New build seems to have killed my Pyboard (now fixed)
Replies: 23
Views: 6968

Re: New build seems to have killed my Pyboard (now fixed)

@pythoncoder if it is really a worn out flash I am seriously interested in getting my hands on this particular board.