About Lee3

Lee3 · 2024-10-03

I working through issues on an STM32G4 where at times I'm not getting the reaction time from the DMA that I would like. I read AN2548, and it is a very helpful resource. However, I'm seeing slightly worse response times than AN2548 would suggest, and...

Lee3 · 2024-08-28

I have a project using all custom code (not HAL) in which I have two 6 byte SPI DMA transactions running periodically based on timers. It's set up so I can even pause the main CPU and these transactions will continue. I've found that in certain condi...

Lee3 · 2024-03-07

I'm trying to send a fixed length packet in SPI slave mode from the STM32 via DMA. The SPI master may send/recv longer than that fixed length packet. It would be nice if the STM32 just sends 0 one the transactions is complete, but it seems to want to...

Lee3 · 2022-09-12

I'm interested in trying to synchronize my system to USB start of frame packets. I'm using the CRS system to generate an HSI48 clock. I've considered running that HSI48 clock into MCO and using that as an external clock for a timer. This would enable...

Lee3 · 2021-09-22

I'm configuring i2c with dma using the registers directly. I'm sure I have an error somewhere but I don't have a great idea on where to go next with debugging. Sometimes my i2c transfer goes through expediently, but sometimes it has a long stall afte...

Lee3 · 2024-03-07

I guess I see that 0x02 and 0x80 are 3 and 4 bytes ahead of the end. I added 4 zeros to the outgoing packet and that makes following bytes all 0. Is there any other solution for this?

Lee3 · 2021-09-23

Thanks for the help. Per your comment I did try the two boards comdma, though I couldn't quite get it to work right with the toolchain that I tried. So I looked more at the original problem and realized that it was the device that was doing clock str...

Lee3 · 2021-03-25

Thank you much, that was my issue. My debugging was taking me in the wrong direction otherwise, thinking it was something with the configuration or specific to the encoder mode.

Lee3 · 2019-08-30

So it seems that the issue is just poor HSI accuracy such that autodetect doesn't work. My measured HSI is 16.4 MHz. This is described here: https://community.st.com/s/article/FAQ-DFU-mode-with-system-bootloader-is-not-working-while-USB-doesMy workar...

Lee3 · 2019-08-29

I can connect the debugger when the bootloader is running and see that in fact it's detecting the oscillator as 23 MHz when usb doesn't work. It addition the bootloader does not set HSEBYP. So is it just that the bootloader is not compatible with osc...

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DMA latency

Glitch in SPI DMA transfer seemingly also related to USB on STM32G4

SPI slave mode send data after transaction complete

How can I synchronize a timer to USB SOF?

I2C DMA stall

Re: SPI slave mode send data after transaction complete

Re: I2C DMA stall

Re: Timer interrupt flag behavior in encoder mode

Re: STM32F4 USB DFU bootloader not working reliably

Re: STM32F4 USB DFU bootloader not working reliably