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by dave j
Thu May 23, 2019 1:05 pm
Forum: General discussion
Topic: Rpi as a scan converter / scaler, possible?
Replies: 8
Views: 385

Re: Rpi as a scan converter / scaler, possible?

Thanks, That's great but I was thinking if it support the RGBS or RGBHV basically if it would work with a rgb-scart output of a PAL 50Hz Megadrive console. I'm not a BBC Micro expert, it would anyway looks like they have the same RGB output standard (?). Also is it sold somewhere or the developer h...
by dave j
Thu May 23, 2019 12:58 pm
Forum: General discussion
Topic: Rpi as a scan converter / scaler, possible?
Replies: 8
Views: 385

Re: Rpi as a scan converter / scaler, possible?

Novel, and quite clever. Do note that this is using the Pi in bare metal mode, so it's dedicated to that one task. It's also below SD in resolution (pixel clock of 12 or 16MHz). The 12 and 16MHz pixel clocks are what the BBC uses for its screen modes. The device samples at 96MHz. There are examples...
by dave j
Thu May 23, 2019 9:45 am
Forum: General discussion
Topic: Rpi as a scan converter / scaler, possible?
Replies: 8
Views: 385

Re: Rpi as a scan converter / scaler, possible?

Someone on the stardot Acorn retro forum has produced something that uses a Pi zero and a small CPLD to convert BBC Micro RGB output to HDMI . More recent developments allow it to convert other formats up to VGA. It also does de-interlacing and/or scan lines. Particularly interesting for you is that...
by dave j
Sun May 19, 2019 7:09 pm
Forum: General discussion
Topic: Atmega328p + RPI : ICSP programming providing 3.3V
Replies: 6
Views: 262

Re: Atmega328p + RPI : ICSP programming providing 3.3V

Have your thought of programming the AVR using the Pi? Using this page: Using Raspberry Pi as an Arduino (AVR) programmer and information in the Arduino IDE's files I've been able to program Arduino clones that use ATmega32U4. (That page is a bit out of date - the current Raspbian avrdude is built w...
by dave j
Tue Mar 19, 2019 4:39 pm
Forum: Graphics programming
Topic: 128x160 tft display
Replies: 4
Views: 780

Re: 128x160 tft display

You haven't mentioned/linked to the library you are using which might help people answer. First of all, check if the library you are using has the ability to control display layout - it might already and you won't need the following: If the display does use the ST7735 chip you can find the datasheet...
by dave j
Sun Jan 13, 2019 5:13 pm
Forum: HATs and other add-ons
Topic: Interface boards for Quadrature Encoders
Replies: 3
Views: 529

Re: Interface boards for Quadrature Encoders

If you can't find anything else more suitable, you could consider using an STM32 microcontroller. These are available on a prototyping friendly board very cheaply as blue pills . Many of the timers in these chips have an encoder mode for counting the inputs from a rotary encoder so you could use the...
by dave j
Sun Dec 02, 2018 7:50 pm
Forum: Off topic discussion
Topic: Complete ARM only Instruction Set (as promissed).
Replies: 36
Views: 3041

Re: Complete ARM only Instruction Set (as promissed).

jahboater wrote:
Sun Dec 02, 2018 6:12 pm
There is no portability issue at all using thumb2 since no source code changes are required. It is simply adding the one compiler flag: -mthumb.
Brilliant!
I was thinking of binary portability so you can have a single set of binaries that run on all Pis - same as Raspbian.
by dave j
Sun Dec 02, 2018 5:30 pm
Forum: Off topic discussion
Topic: Complete ARM only Instruction Set (as promissed).
Replies: 36
Views: 3041

Re: Complete ARM only Instruction Set (as promissed).

I think that if GCC can generate it then it should be in the list. After all, they are the instructions actually being used by our software. If I understand correctly GCC will generate also thumb instructions where appropriate. I have not been able to verify this. GCC can generate thumb instruction...
by dave j
Wed Nov 28, 2018 2:51 pm
Forum: Off topic discussion
Topic: Putting the RPi in the perspective, looking Retro.
Replies: 38
Views: 4001

Re: Putting the RPi in the perspective, looking Retro.

Copper: Only the Amiga had a Copper. Today the same thing can be done on the RPi with ease, though differently. This requires a small amount of code on the GPU, though within our limits, to implement the equivalent of a display list, and tell the DMA what to do. Though we only have one horizontal a...
by dave j
Tue Nov 20, 2018 3:46 pm
Forum: General discussion
Topic: Hexdump outputting too many radixes (was) VERY ANNOYING!!! [Solved]
Replies: 9
Views: 391

Re: Hexdump outputting too many radixes VERY ANNOYING!!!

You're much better off saving your BMP file in a format that doesn't have a header (or at least a fixed size one so you can discard the data you don't want). That 16 x 777 radixes is a) because it includes the BMP header, b) because you've got a 24 bit per pixel BMP file rather than a 16 bit one nee...
by dave j
Mon Nov 12, 2018 2:10 pm
Forum: HATs and other add-ons
Topic: TV HAT, missing EPG info.
Replies: 1
Views: 727

Re: TV HAT, missing EPG info.

Just as an addendum to this. I found that the EPGs for some of the channels didn't update straight away. They did update overnight though so if you've done what itsmedoofer suggests and you still haven't got all the EPG info, try waiting a bit.
by dave j
Sun Nov 04, 2018 8:21 pm
Forum: General discussion
Topic: Does not start app on Raspberry Zero cross-compiled in Linux 64
Replies: 7
Views: 452

Re: Does not start app on Raspberry Zero cross-compiled in Linux 64

This bit in your ./configure command -device linux-rpi3-g++ looks like it's specifying compile for Pi3. You need to find what the value should be for Pi0. The reason the code works when compiled on your Pi3 it that Raspbian is configured to compile code that is compatible with all Pi versions. You n...
by dave j
Mon Oct 22, 2018 6:40 pm
Forum: Off topic discussion
Topic: Add Analog to Digital pins to the pi
Replies: 21
Views: 4043

Re: Add Analog to Digital pins to the pi

Just saying "add analog inputs to the Pi" is too vague to be meaningful. What resolution? What sample rate? How much jitter of sample times is acceptable (one built into the Pi is going to be fighting other circuitry for access to the memory bus)? How many channels? How many simultaneous channels? W...
by dave j
Fri Sep 07, 2018 7:12 pm
Forum: OpenGLES
Topic: Sliced front buffer rendering
Replies: 0
Views: 5163

Sliced front buffer rendering

Qualcomm and ARM GPUs have the ability to render to part of the front buffer without requiring loading and saving the rest of it - which is slow. (Qualcom have their QCOM_tiled_rendering extension and ARM uses scissor boxes.) It also looks like the Eric Anholt's driver supports it using scissoring ....
by dave j
Mon Jan 22, 2018 4:23 pm
Forum: General discussion
Topic: Arcade Monitor - Rotated display NOW Jumpy Graphics
Replies: 2
Views: 392

Re: Arcade Monitor - Rotated display NOW Jumpy Graphics

This is a known issue. Get your emulator to do the rotation rather than the config.txt entry.
by dave j
Wed Nov 15, 2017 11:52 am
Forum: C/C++
Topic: Help with ILI9225 display
Replies: 4
Views: 1885

Re: Help with ILI9225 display

First of all, if you haven't proved your software SPI implementation works by writing to a known working SPI implementation (e.g. one on your Arduino) ensure that it does - trying to debug two things at once needlessly complicates things. As to your screen code. Your drawPixel function defines a win...
by dave j
Tue Oct 03, 2017 8:25 pm
Forum: General discussion
Topic: Why no enthusiast Raspberry Pi products?
Replies: 53
Views: 6508

Re: Why no enthusiast Raspberry Pi products?

Anyone have anything interesting to say that's actually on topic here? The RetroPie people mentioned on their site download figures of hundreds of thousands - a lot less than 1 million. Compare that with the 15 million plus Pis sold. And that's not accounting for people who aren't using their Pis s...
by dave j
Sun Aug 20, 2017 2:42 pm
Forum: OpenGLES
Topic: OpenglES draw multiple objects
Replies: 6
Views: 2742

Re: OpenglES draw multiple objects

There's no reason why it wouldn't work for objects that move. It just passes the transform matrix as vertex attributes rather than uniforms. You just need to calculate the transform matrix for each object (or pass the minimum you need to change, say position, and calculate the transform matrix in th...
by dave j
Sat Aug 19, 2017 11:23 am
Forum: OpenGLES
Topic: OpenglES draw multiple objects
Replies: 6
Views: 2742

Re: OpenglES draw multiple objects

First of all you should look into using index buffers and glDrawElements rather than using glDrawArrays as it will help speed thing up. NVIDIA produced a paper on GLSL Pseudo-Instancing . It's very old but the technique should be usable with OpenGLES 2.0. You still need a draw call for each mesh but...
by dave j
Thu Aug 03, 2017 8:46 am
Forum: General discussion
Topic: STICKY: NEW FORUM SKIN - Comments here please.
Replies: 288
Views: 52551

Re: STICKY: NEW FORUM SKIN - Comments here please.

latest iteration looks fairly nice (glad to have the "return to <current forum>" tag at the bottom, for instance), BUT can you *please* go back to actual BLACK text. This medium/light gray is extremely hard on these old eyes. This. It's not hard to set CSS to use the text colour the user has specif...
by dave j
Wed Jul 26, 2017 9:46 am
Forum: General discussion
Topic: STICKY: NEW FORUM SKIN - Comments here please.
Replies: 288
Views: 52551

Re: STICKY: NEW FORUM SKIN - Comments here please.

The text used for posts is still too low contrast for me. I know there's a fashion for using grey text because some people find it more readable but that just makes it less readable for others - you're never going to be able to pick colours that suit everybody. The proper solution to this is to not ...
by dave j
Tue Apr 04, 2017 5:40 pm
Forum: Graphics programming
Topic: OpenGL - performance of new driver
Replies: 10
Views: 4473

Re: OpenGL - performance of new driver

If you're used to desktop systems it's worth noting that the VC4, in common with most other mobile GPUs, is tile based and this has performance implications. The OpenGL Insights book has a chapter on performance tuning for tile based architectures (which can be downloaded from that link).
by dave j
Mon Mar 20, 2017 2:50 pm
Forum: Graphics programming
Topic: BMP Out in C
Replies: 25
Views: 5296

Re: Real-Time 2D Graphics support for UN*X CLI's

OK, got the COOLEST thing for you guys and gals. How does Real-Time 2D graphics support for UN*X sound? Its definitely fun to play with but very jerky. I can do that in BASIC on a Pi. Very smooth. You want easy real-time 2D graphics under Unix/Linux/*x ? Use SDL. It's a cross platform library initi...
by dave j
Sun Mar 12, 2017 11:08 pm
Forum: Troubleshooting
Topic: gpio only 1v. output
Replies: 9
Views: 1725

Re: gpio only 1v. output

Are you sure you're using RPi.GPIO correctly? This documentation is inconsistent with the code you've posted.

GPIO.setup() is used to define whether a pin is an input or and output.
GPIO.output() is used to set it high or low.
by dave j
Sun Mar 12, 2017 4:24 pm
Forum: General discussion
Topic: Using RPi to flash Arduino bootloader
Replies: 14
Views: 5587

Re: Using RPi to flash Arduino bootloader

Actually, I didn't want to use the IDE, it sort of gets in the way but it has the flash boot loader command. I typically have no idea what I am doing I just keep trying until something happens so I got slightly confused between what I thought I needed and what I actually needed. Right now without t...

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