Search found 581 matches

Go to advanced search

by cleverca22
Mon Jun 22, 2020 6:27 pm
Forum: General discussion
Topic: PIGPIO jitterless wave generation.
Replies: 38
Views: 1007

Re: PIGPIO jitterless wave generation.

https://github.com/librerpi/rpi-open-firmware/blob/b82a33aaba5210c8c458889a163db425ca6ea68c/utils/kms-test.cpp#L141-L172 with this code, i can now generate a uart stream on one bit of the DPI interface (GPIO4), its transmiting at 5,000,000 baud with the example config.txt in theory, it could transmi...
by cleverca22
Sun Jun 21, 2020 9:54 pm
Forum: General discussion
Topic: PIGPIO jitterless wave generation.
Replies: 38
Views: 1007

Re: PIGPIO jitterless wave generation.

PV0 raw dump: 0x7e206000 05 40 10 01 03 00 00 00 00 00 00 00 01 00 00 00 |.@..............| 0x7e206010 64 00 00 00 01 00 00 00 64 00 00 00 00 00 00 00 |d.......d.......| 0x7e206020 00 00 00 00 00 00 00 00 00 00 00 00 44 04 00 00 |............D...| 0x7e206030 00 00 00 00 20 00 00 00 01 00 00 00 00 0...
by cleverca22
Sun Jun 21, 2020 5:12 pm
Forum: Beginners
Topic: How to change the duty cycle of hardware pwm in pigpio?
Replies: 3
Views: 129

Re: How to change the duty cycle of hardware pwm in pigpio?

you dont appear to have any delays in the code, so its going to likely be changing the duty cycle multiple times per cycle

youll want to add a sleep at some point, to make it wait before doing the next change
by cleverca22
Sun Jun 21, 2020 1:58 pm
Forum: General discussion
Topic: PIGPIO jitterless wave generation.
Replies: 38
Views: 1007

Re: PIGPIO jitterless wave generation.

More questions about DPI. 1. If I understand correctly in time of vsync there is gap in stream (bad). 2. Can DPI be clocked under 5MHz. 3. When doing that pi can not be attached to monitor or DPI can have "other" frame buffer. 1: the lowest ive gotten vsync is 1 scanline, but you can control the wi...
by cleverca22
Sun Jun 21, 2020 3:50 am
Forum: General discussion
Topic: PIGPIO jitterless wave generation.
Replies: 38
Views: 1007

Re: PIGPIO jitterless wave generation.

What was maximal pixel clock (width*height*framerate) that did work for you? Doc sample is 32MHz only, is 200MHz or 400MHz viable? I will try myself when back home, and will be able to check with my 400Msps logic analyzer ... an old DPI thread (for a CM3) says that the max rate for all gpio (includ...
by cleverca22
Sat Jun 20, 2020 11:28 pm
Forum: General discussion
Topic: PIGPIO jitterless wave generation.
Replies: 38
Views: 1007

Re: PIGPIO jitterless wave generation.

is the uart tx only, or rx+tx?
why does the uart have to be bit-banged?
just configure the uart for the desired baud
by cleverca22
Sat Jun 20, 2020 9:35 pm
Forum: General discussion
Topic: PIGPIO jitterless wave generation.
Replies: 38
Views: 1007

Re: PIGPIO jitterless wave generation.

i have been experimenting with abusing the DPI peripheral for exactly this kind of thing... That is good hacking. Now try and do all that whilst waiting on bytes from a serial input and responding appropriately. you can just read the serial port as normal, and that wont interfere with the generated...
by cleverca22
Sat Jun 20, 2020 8:28 pm
Forum: General discussion
Topic: PIGPIO jitterless wave generation.
Replies: 38
Views: 1007

Re: PIGPIO jitterless wave generation.

i have been experimenting with abusing the DPI peripheral for exactly this kind of thing https://www.raspberrypi.org/documentation/hardware/raspberrypi/dpi/README.md basically, configure it to use a custom width/height/pixelclock, and then fill a framebuffer with some RGB888 image data the DPI perip...
by cleverca22
Sat Jun 20, 2020 11:50 am
Forum: General discussion
Topic: Question about Raspberry Pi 4 LED design
Replies: 23
Views: 1018

Re: Question about Raspberry Pi 4 LED design

Thanks for the replies. Maybe having it blink so fast when on that it appears very dim and go bright with shutdown might be better than the current situation. Staying fully off when on, aside from just rubbing me the wrong way, would look exactly the same as power removed so not that great. However...
by cleverca22
Sat Jun 20, 2020 11:48 am
Forum: General discussion
Topic: Getting shock from micro hdmi port when connected to tv hdmi port
Replies: 66
Views: 2332

Re: Getting shock from micro hdmi port when connected to tv hdmi port

there is another outlet in this house, that literally exploded one of those 3 bulb neon testers, after it gave me a nasty shock the GND pin shorted to HOT, and not a weak short, a full on short that can power things if an electrician knew that its still like that, he would likely be having nightmar...
by cleverca22
Sat Jun 20, 2020 2:42 am
Forum: Graphics programming
Topic: Is the FBIO_WAITFORVSYNC ioctl implemented in Rpi's fb? [OBSOLETE info]
Replies: 56
Views: 29705

Re: Is the FBIO_WAITFORVSYNC ioctl implemented in Rpi's fb?

this thread has been dead for 4 years!, the software managing gfx has evolved massively since then
by cleverca22
Sat Jun 20, 2020 2:41 am
Forum: General discussion
Topic: Question about Raspberry Pi 4 LED design
Replies: 23
Views: 1018

Re: Question about Raspberry Pi 4 LED design

Yes,missing the 10 blinks or forgetting that they ever happened. That is exactly why IMO the current behaviour is less than useful. When it's on missing a few ms of voltage drop is great but that has no point when the unit is off. I'd personally be most interested in whether it's safe to remove pow...
by cleverca22
Sat Jun 20, 2020 2:38 am
Forum: General discussion
Topic: Getting shock from micro hdmi port when connected to tv hdmi port
Replies: 66
Views: 2332

Re: Getting shock from micro hdmi port when connected to tv hdmi port

but once i moved the scope to the same power strip as the pi, the difference dropped to almost nothing, and everything worked great once more That suggests you may have an earth fault on one or other of the sockets. This would be rated as "potentially dangerous: the safety of those using the instal...
by cleverca22
Fri Jun 19, 2020 9:18 pm
Forum: General discussion
Topic: Question about Raspberry Pi 4 LED design
Replies: 23
Views: 1018

Re: Question about Raspberry Pi 4 LED design

If the designers had wanted to indicate "it's shut down properly, so you can safely remove power" then they may have done what you suggest. But that isn't what they wanted - they wanted to indicate "5v is good, and has been for the last few ms" i believe all models of pi will blink the act led 10 t...
by cleverca22
Fri Jun 19, 2020 9:04 pm
Forum: General discussion
Topic: Getting shock from micro hdmi port when connected to tv hdmi port
Replies: 66
Views: 2332

Re: Getting shock from micro hdmi port when connected to tv hdmi port

P.S. the Type 2 "tingles" is actually very common, seen as many people don't plug their TV or Monitor in a grounded outlet. alsmost all RPI's out there have a permanent 110V (for europe) or 55V (for US etc) AC voltage relative to earth on them, and almost nobody notices this, as the current flow is...
by cleverca22
Fri Jun 19, 2020 3:20 pm
Forum: General discussion
Topic: What clock does the SPI SCLK use?
Replies: 4
Views: 147

Re: What clock does the SPI SCLK use?

https://elinux.org/The_Undocumented_Pi for all of the VC4 models (rpi0 to rpi3) the main crystal is 19.2mhz that then goes into the PLL's which boost the freq up (where depends to depends on firmware, config.txt, and powersaving stuff, but some clocks are relatively constant across all configs) each...
by cleverca22
Fri Jun 19, 2020 12:24 pm
Forum: C/C++
Topic: [SOLVED] Decoding revision code
Replies: 3
Views: 310

Re: [SOLVED] Decoding revision code

just as an extra point of reference, this is how ive done revision decoding: uint32_t revision = otp_read(30); // https://www.raspberrypi.org/documentation/hardware/raspberrypi/revision-codes/README.md printf("\nHW revision: 0x%08x\n", revision); if (revision & (1 <<23)) { // new style revision prin...
by cleverca22
Thu Jun 18, 2020 5:54 pm
Forum: Camera board
Topic: Raspberry Pi Cameras - Hazardous Environement
Replies: 2
Views: 175

Re: Raspberry Pi Cameras - Hazardous Environement

there is also another thread about encasing the camera in epoxy that could potentially be used to better reinforce it, so the board doesnt just pop like an over-inflated balloon when used to seal a hole just having the board fully inside the enclosure may also work, if the main sensor cavity isnt pe...
by cleverca22
Thu Jun 18, 2020 5:30 pm
Forum: Bare metal, Assembly language
Topic: Bare Metal Audio -- PCM Module Use
Replies: 2
Views: 417

Re: Bare Metal Audio -- PCM Module Use

i believe there are 3 ways to output audio on a pi 1: 2 PWM channels fed thru a low-pass filter and the headphone jack, i think the firmware manages most of that, and you just put samples in the right area of ram 2: the HDMI port (dont know much details about this) 3: the I2S port (digital audio out...
by cleverca22
Tue Jun 16, 2020 10:54 am
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: whats the difference between /dev/spidev0.0 and /dev/spidev0.1
Replies: 2
Views: 166

Re: whats the difference between /dev/spidev0.0 and /dev/spidev0.1

i believe thats the chip select line

which device you open, sets which chip select line goes active when you transmit data, letting you put 2 SPI devices on the same port, just give them different chip selects
by cleverca22
Mon Jun 15, 2020 5:42 pm
Forum: Troubleshooting
Topic: Raspberry pi4 b 4gb model not booting up no green light
Replies: 3
Views: 89

Re: Raspberry pi4 b 4gb model not booting up no green light

did you read the boot problems sticky?
what does it do if you dont have any SD card in the pi?
by cleverca22
Mon Jun 15, 2020 5:35 pm
Forum: Compute Module
Topic: How to erase CM3+
Replies: 2
Views: 186

Re: How to erase CM3+

if it says `BCM2710 boot` then you have to run usbboot to switch it over to mass-storage mode, then it should show up as a disk
by cleverca22
Mon Jun 15, 2020 2:39 pm
Forum: Graphics programming
Topic: DPI config from userland
Replies: 10
Views: 532

Re: DPI config from userland

shared: pv0 audio domain, DSI0/DPI pv1 audio domain?, DSI1/SMI VC4: pv2 is HDMI/SDTV VC6: pv2 HDMI0 pv3 VEC pv4 HDMI1 VC4 VC6 0x7e206000 pv0 pv0 0x7e207000 pv1 pv1 0x7e20a000 pv2? 0x7e216000 pv4 0x7e807000 pv2 0x7ec12000 pv3 is this more accurate then?
by cleverca22
Mon Jun 15, 2020 2:21 pm
Forum: Graphics programming
Topic: DPI config from userland
Replies: 10
Views: 532

Re: DPI config from userland

ah, i think i see the cause of my confusion

the PV at 0x7e807000 is missing, so thats -1 +3, that explains how we got to 5, despite gaining 3 new ones
by cleverca22
Mon Jun 15, 2020 1:53 pm
Forum: C/C++
Topic: Edge detection using /dev/gpiomem
Replies: 22
Views: 1056

Re: Edge detection using /dev/gpiomem

the protocol youve described sounds similar to the old lirc api for kernel<->userland communications the kernel would gather a packet of lenghts, for how long the signal was low and high, until it hits some max packet size or the signal stops toggling and then lircd would decode that in userland, wh...

Go to advanced search