 Notice. New forum software under development. It's going to miss a few functions and look a bit ugly for a while, but I'm working on it full time now as the old forum was too unstable. Couple days, all good. If you notice any issues, please contact me. |
Forum Index : Microcontroller and PC projects : A selfmade breadboard friendly HDMI plu
  Page 2 of 2 |
|||||
| Author | Message | ||||
Mixtel90 Guru  Joined: 05/10/2019 Location: United KingdomPosts: 7683 |
The simple resistor-capacitor PWM filter is actually very poor. It will extract audio, it's true, but the frequency response is poor and at the top end there is virtually no reduction in the 44kHz carrier signal that the PWM uses. That means that it makes a mess if you feed it into a decent audio system - and it's quite possible that it could damage some tweeters. Volhout's filter cuts off sharply at the top end, removing almost all the carrier frequency. It's worth using even if it means buying a few cheap components off ebay or AE. You can get away with the simplest filter if you are sticking to little PC speakers or headphones. . Edited 2025-06-07 06:02 by Mixtel90 Mick Zilog Inside! nascom.info for Nascom & Gemini Preliminary MMBasic docs & my PCB designs |
||||
| dddns Guru Joined: 20/09/2024 Location: GermanyPosts: 426 |
Thanks Mick for that info, I got the coils and capacitors to build Volhouts version. Next for me is to get the sdcard and system spi running, as well for i2c and the ds1307..I know poor chip :) |
||||
| dddns Guru Joined: 20/09/2024 Location: GermanyPosts: 426 |
@Stan I would see sdcard,rtc and audio as mandatory..it's so easy and cheap in any way(except my VS1053 :( ) |
||||
| Mixtel90 Guru Joined: 05/10/2019 Location: United KingdomPosts: 7683 |
I rather like the VS1053. It works well. Of course there are other choices too: The MCP DAC chips - your choice of 8-bit, 10-bit or 12-bit audio and takes up less space than Volhout's filter. It costs more though. Puts a bit of load on the processor but the 2350 probably doesn't notice. Tucks away nicely underneath the Pico. :) I2S audio too (PCM5102 for example). I have a couple of modules but haven't used them yet. Cheap and, reportedly, excellent audio quality. I'd avoid PWM audio now. It's not easy getting rid of CPU noise on the audio (careful routing of signals and grounds, using a linear regulator to get rid of the switcher). Digital audio (any version) makes it so much easier. Mick Zilog Inside! nascom.info for Nascom & Gemini Preliminary MMBasic docs & my PCB designs |
||||
stanleyella Guru Joined: 25/06/2022 Location: United KingdomPosts: 2474 |
nothing is mandatory but yeah you're supposed to have an sd card and audio and use usb hdmi and have a usb keyboard and mouse. do you? if I use a usb to ttl then that will power the pico, pin 40. yhat will drive the usb kb/mouse.. even a wireless usb dongle works for a kb/mouse screen. problems are sd card needs 3V so want it on one side of board ,not OPTION SDCARD GP22, GP6, GP7, GP4 there is a lot of difference from just hdmi and usb hdmi |
||||
| stanleyella Guru Joined: 25/06/2022 Location: United KingdomPosts: 2474 |
it was never a mp3 player or a retro game machine. it was supposed to be a boot to basic design. why? |
||||
| Mixtel90 Guru Joined: 05/10/2019 Location: United KingdomPosts: 7683 |
It still is. You just take it as far as you want to go. You can still use it as an embedded controller with no display or with some sort of minimal or touch screen display. It can still scan a numeric pad. It's just as valid to use VGA & a PS2 keyboard now as it ever was because it's still a "boot to basic" machine. It still has no OS. I's just that now you can do other things *if you want to*. It's all optional. Nothing has changed fundamentally. :) You don't need to use the Library. You still have flash slots and drive A: built in - which means that you don't need a SD card in some cases. That's the beauty of the PicoMite. It can be anything from rock bottom up to a pretty amazing sound and graphics machine. It's all your own choice. :) Mick Zilog Inside! nascom.info for Nascom & Gemini Preliminary MMBasic docs & my PCB designs |
||||
| Page 2 of 2 |
|||||
 Print this page |
 |
The Back Shed's forum code is written, and hosted, in Australia. | © JAQ Software 2025 |
