Retro Video Generator

-
I found this project while I was experimenting with the NTSC Color video generator some time ago, but finally got round to ordering the parts I needed recently.

Thanks to Grant Searle for the awesome work on the project, which seems to have slipped into the recesses of the internet. This may be because unlike the classic 'TV_Out' for the Arduino, you need a programmer to upload the hex file directly to microcontroller.

The circuit uses a 74HCT166 parallel in/serial out shift register, clocked at the same 16MHz as an ATmega328P microcontroller, giving the speed necessary for a 640x200 pixel display.
The biggest problem I had was with the ATmega328P ICs I bought on Aliexpress. These seemed to have the option fuses set for a slow internal clock and it took a bit of messing about to get the fuses cleared so they could be set for the external crystal.

Best of all, data is input via a standard I2C 2-wire interface which will connect to PIC microcontrollers (which I have a box of!), finally giving me a flexible way to generate video for PIC-Jal projects.

I'm using the Avrdudess GUI to upload the hex files.

UPDATE 30/10/23


I followed Grant's instructions on how to modify his assembly code to hardwire the I2C option and change the device address. After a bit of fiddling with the Avra assembler, I got it working. Hardwiring the options saves a couple of components and a few lines of code and having multiple addresses means I will be able to drive 2 video generators on the I2C bus.

Comments

Post a Comment

Popular posts from this blog

Update on the touch monitor

-
This is tantalising... I found some data on driver chips used on these low-cost monitors and some of them have an I2C connection for sending pixel data directly to the screen. This may be to allow text or graphics overlay. Anyway the chip on my 7" screens is an AR05C-LF and there are millions of these in stock in the far east, but I can't so far find a data sheet for this chip or its sibling the AR05CA-LF. Being able to send digital pixel data via I2C directly to the screen would be, well, brilliant.
Read more

Apple iPad SSH Connection to Linux Laptop

-
Image
I was given this older Apple iPad a while back and was looking into installing Linux on it. Options are limited, but it is possible to install a shell to the iPad and run command line stuff.  SSH is always a bit of fun so I logged into my Linux Mint laptop remotely for a giggle. It was interesting running a few simple commands from the iPad. My cheapo Bluetooth keyboard came in very useful although I discovered that the iPad's OS version predated mouse support so the trackpad didn't work. Going a step further, I got my Raspberry Pi going again and was able to install VNC on the iPad and remotely control the Raspberry Pi's desktop. Could be useful! I'm also looking at fitting a small heatsink and 5-volt fan (recovered from a broken laptop) to the Raspberry Pi and over clocking it to 1GHz.
Read more

Skoda Rapid Heater Re-circulation Motor Repair

-
Image
In the autumn of 2018 the heater re-circulation motor (I'll refer to this as the HRM from now on) in my 2015 Skoda Rapid decided to fail. It had been making a grinding and clicking noise for a while and I had asked the local Skoda dealer to look into this during a routine service, which they didn't, but more on that later. The problem was that the motor failed in the re-circulate setting so the interior of the car steamed up very quickly and the windscreen couldn't be de-misted. Putting the air-conditioning on was a short-term solution up until the outside temperature dropped below 10 Celsius and that stopped working! There isn't a lot of information online about the Rapid because it is a less common model than other Skodas, but it shares a lot of design with the Fabia and Octavia so it wasn't too hard to get diagrams showing where the motor was and how it works. To get at the HRM I had to remove the glove box (7 Torx screws) and the heater motor (5 Torx screws),
Read more