Search found 46 matches

by Y@@J
Wed Jan 20, 2021 5:35 pm
Forum: General discussion
Topic: SPI/DMA Filtering frames on the fly
Replies: 2
Views: 61

Re: SPI/DMA Filtering frames on the fly

spi_rx_dma_disable() does not do it (it kills Rx, and spi_rx_dma_enable() is not enough to restore it. Finally, the simplest (and fastest ?) I could do : void ISR_NSS_1() // RISING { volatile uint8_t* p = SPI_1_Rx_Buffer; // keep pages only : 0x10 0x00 0xBn (0 <= n < 8) if (*p++ != 0x10 || *p++ !=0...
by Y@@J
Tue Jan 19, 2021 6:19 pm
Forum: General discussion
Topic: SPI/DMA Filtering frames on the fly
Replies: 2
Views: 61

SPI/DMA Filtering frames on the fly

Hi, for my app, I need to discard some SPI frames. As I understand SPI+DMA, all frames have to be the same size, the buffer size depending on the frames size. I have some variable length frames that have to be discarded (they are useless). They are easily recognizable with their first byte, and thay...
by Y@@J
Sat Jan 16, 2021 3:13 am
Forum: Off topic
Topic: Need advice about decoding ST7920 commands
Replies: 1
Views: 102

Need advice about decoding ST7920 commands

Hi, I recently made a OLED emulator, want to make one for the ST7920 LCD (AKA RepRapDiscount Full Graphic Smart Controller), SPI mode. The OLED protocol was very simple (reason why I started with...), the ST7920 is much more complex ! The datasheet is really unclear to me. For now, much of my knowle...
by Y@@J
Sun Jan 10, 2021 5:56 pm
Forum: Off topic
Topic: Is there some Linux gurus here ?
Replies: 6
Views: 238

Re: Is there some Linux gurus here ?

The app progressed a lot, but still unable to code for the Matchbox window manager (very little information, after hours on the web). And being an absolute newbie in Pi coding, I don't even know the "good" keywords. I attempted to subscribe to the RaspBerry forums, but for some reason it failed (no ...
by Y@@J
Tue Jan 05, 2021 1:28 am
Forum: Off topic
Topic: Is there some Linux gurus here ?
Replies: 6
Views: 238

Re: Is there some Linux gurus here ?

For now, it is tiny (128x64), but alive, in a "always on top" X11 window. Run as a daemon, no Title bar, as reactive as the OLED display, popping up and disapearing pressing a button, and zero flickering when over the video viewer. In fact, it is not always on top : if Chromium browser is full scree...
by Y@@J
Mon Jan 04, 2021 6:48 pm
Forum: Off topic
Topic: Is there some Linux gurus here ?
Replies: 6
Views: 238

Re: Is there some Linux gurus here ?

No Python ! No QT ! And even more : no Qt with Python ! Want to stay as low level as possible, and avoid such a language. I'll have to use it at some point, but no need for now. Stopped using Basic 35 years ago, I will not use Python now : it's even worse. Finally, I started with a "Hello World !", ...
by Y@@J
Mon Jan 04, 2021 12:39 am
Forum: Off topic
Topic: Is there some Linux gurus here ?
Replies: 6
Views: 238

Re: Is there some Linux gurus here ?

It blit on the frame buffer, bare metal. Output being a HDMI 1024x600 LCD touchscreen. Your answer is definitely NOT off topic ! It is exactly in topic. The little app called xeyes ! I've seen this widget years ago, and didn't remember. Now searching for the XEyes C source : it is EXACTLY what I nee...
by Y@@J
Sun Jan 03, 2021 3:41 pm
Forum: Off topic
Topic: Is there some Linux gurus here ?
Replies: 6
Views: 238

Is there some Linux gurus here ?

Hi, and happy new year ! I am just discovering Linux coding (on RasPi) because I wrote someting that runs on a STM32, and is displayed on a RasPi LCD. Bitmaps are sent by the STM32 to the RasPi over SPI (Roger's Core) in full duplex mode @16MHz (works GREAT !). These bitmaps (70 to 110/second) are b...
by Y@@J
Thu Dec 31, 2020 12:06 am
Forum: General discussion
Topic: emulating a OLED display on a VGA and/or a LCD monitor
Replies: 64
Views: 2897

Re: emulating a OLED display on a VGA and/or a LCD monitor

Currently experimenting with another approach : I finally had a look under the RaspBerry Pi hood : drawing directly in the frame buffer ("bare metal programming"). It is interesting because the image of the OLED appears as an overlay, over the underlaying desktop, console, or OctoPrint/Octolapse (Oc...
by Y@@J
Mon Dec 28, 2020 9:53 pm
Forum: General discussion
Topic: emulating a OLED display on a VGA and/or a LCD monitor
Replies: 64
Views: 2897

Re: emulating a OLED display on a VGA and/or a LCD monitor

Added a timeout functionality in the reveive function. micros() or similar function is not usable with TVOut. TVOut has its own millis(), but its granularity is far too coarse (16 to 20ms depending on NTSC or PAL). A simple counter does it. (if the STM32 wasn't responding for whatever reason, TVOut ...

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