Post #1697208
2026-04-25 12:58 UTC
Finally!! Perfect sampling! Still a bit of expected garbage on the vertical back and front porches but the sampling works, totally stable and pixel sharp! And even better, 100% PIO and DMA based! The only thing the CPU core is doing is pre-calculating a table with the sampling timing (based on Bresenham sampling) and adjusting the DMA addresses on interruptions. #RetroApple
Replies (1)
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@arroz@mastodon.social 2026-04-25 14:43
Here’s a fun one, I was trying to make sure the resistor based trick to shift from 5 to 3.3V worked but because my current generator is another Pico (that works at 3.3V) I’m using an HCT chip to bring it up to 5V. It works for both v-synch and h-synch but the chip can’t switch fast enough for passing the video signal properly, so the background checkerboard pattern turns to solid black! And you can see the slight delay it adds, as the image is shifted right a pixel or two. #RetroApple