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by racemaniac
Thu Feb 23, 2017 3:55 pm
Forum: General discussion
Topic: Planning to add callback to the SPI DMA functions (dmaSend, dmaTransfer...)
Replies: 36
Views: 279

Re: Planning to add callback to the SPI DMA functions (dmaSend, dmaTransfer...)

ugh, that eternal trade off between performance and usability of a framework ^^'
there indeed is no silver bullet or "best" solution >_<. i'd still like the cheap setup functions for when using DMA directly, but for usage in frameworks, the full setup is indeed the safer choice.
by racemaniac
Thu Feb 23, 2017 1:05 pm
Forum: Off topic
Topic: Kicad
Replies: 20
Views: 206

Re: Kicad

i've read some people advising against via's in pads, since the solder meant for the pad can go into the via, and can result in bad smd soldering. but haven't tried it myself (for that reason i put the vias a bit besides the pad on my board to avoid this from happening).
by racemaniac
Thu Feb 23, 2017 10:28 am
Forum: Off topic
Topic: Kicad
Replies: 20
Views: 206

Re: Kicad

after some googling, i think what you want is a tented via under your pad (it'll still be a via, but on the surface it is a normal pad) this page has a nice overview of the kinds of vias that exist: https://www.pcbuniverse.com/pcbu-tech-tips.php?a=5 now only to figure out how to do that in kicad ^^ ...
by racemaniac
Thu Feb 23, 2017 9:20 am
Forum: Off topic
Topic: Kicad
Replies: 20
Views: 206

Re: Kicad

And another KiCad problem PCB seems to have something which stops me placing tracks, when the distance to objects is small, I suspect this is some sort of preference, but I'd rather it just warned me when I did an error check, rather than preventing me routing the track in the first place that's in...
by racemaniac
Thu Feb 23, 2017 9:18 am
Forum: Off topic
Topic: Kicad
Replies: 20
Views: 206

Re: Kicad

Just to continue this active thread about KiCad I seem to have run into a problem with creating a KiCad PCB symbol. Its an SMD part, https://infocenter.nordicsemi.com/topic/com.nordic.infocenter.nrf52840.ps/chapters/mec_spec/doc/image/mec_dim_qiaa-01.svg But looking at the reference PCB designs whi...
by racemaniac
Thu Feb 23, 2017 8:51 am
Forum: General discussion
Topic: Planning to add callback to the SPI DMA functions (dmaSend, dmaTransfer...)
Replies: 36
Views: 279

Re: Planning to add callback to the SPI DMA functions (dmaSend, dmaTransfer...)

stevestrong wrote:In my code I initialized the DMA once (dmaSendInit()), then I just updated the number of data to transfer and the pointer in dmaSendBuffer() and enabled the DMA, so that the overhead could be kept minimal.
I will post my version here in the evening.

yup, same here when doing dma :).
by racemaniac
Thu Feb 23, 2017 8:31 am
Forum: General discussion
Topic: Planning to add callback to the SPI DMA functions (dmaSend, dmaTransfer...)
Replies: 36
Views: 279

Re: Planning to add callback to the SPI DMA functions (dmaSend, dmaTransfer...)

indeed :). It would still be nice to be able to configure that you won't reuse the dma channel for something else and get the cheaper dma setup (likely the most often usecase since so far dma is hardly used anyway ^^) If I understand right, you are suggesting to add functions that could repeat a dm...
by racemaniac
Wed Feb 22, 2017 7:28 pm
Forum: General discussion
Topic: Planning to add callback to the SPI DMA functions (dmaSend, dmaTransfer...)
Replies: 36
Views: 279

Re: Planning to add callback to the SPI DMA functions (dmaSend, dmaTransfer...)

Extract from RM0008: So the CPU may be slowed down to the half of its speed capacity. The higher the SPI clock, the worse the situation for the CPU if performs a lot of memory accesses. i know that, but suppose you have spi running at max speed (is half the clock speed i believe, so 36Mhz for an st...
by racemaniac
Wed Feb 22, 2017 3:28 pm
Forum: General discussion
Topic: Planning to add callback to the SPI DMA functions (dmaSend, dmaTransfer...)
Replies: 36
Views: 279

Re: Planning to add callback to the SPI DMA functions (dmaSend, dmaTransfer...)

Extract from RM0008: 13.3 DMA functional description The DMA controller performs direct memory transfer by sharing the system bus with the Cortex®-M3 core. The DMA request may stop the CPU access to the system bus for some bus cycles, when the CPU and DMA are targeting the same destination (memory ...
by racemaniac
Wed Feb 22, 2017 12:09 pm
Forum: Postbag
Topic: Racemaniac's postbag
Replies: 23
Views: 393

Re: Racemaniac's postbag

continuing the meter saga: i also bought a basic UNI-T clamp meter: https://www.aliexpress.com/item/UNI-T-UT216A-Auto-Range-Multimeter-Mini-True-RMS-Digital-Clamp-Meter-w-NCV-Capacitance-AC/32604877740.html As mentioned somewhere else, i'm building a simple spotwelder from an old microwave transform...

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