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Forum Index : Microcontroller and PC projects : PicoMite 2 HDMI USB I2S board....
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Grogster Admin Group  Joined: 31/12/2012 Location: New ZealandPosts: 9877 |
Very sexy!    Easy to setup, cheaper to produce then the CMM2G2v2(with no disrespect), and lovely feature-set. I've only now had a chance to play with these, as up until now, I have been busy with work. But now I am on my Christmas holiday, I can spend a bit of time, tinkering with things like this. I have not yet tried out everything, but I must spew forth, my absoulute LOVE of the included audio DAC chip. This is BRILLIANT, when hooked up to a good amplifier. Again, no disrespect to the wonderful LPF on the CMM2 etc - Volhort did brilliant work there, but the fact is, that a dedicated DAC will always be better then PWM + LPF. Four-port USB hub is an excellent idea, and with the HDMI video, this thing is just about perfect. The only complaints you will get now, are those moaning that the audio is not on the HDMI port.....because people are never happy.  Smoke makes things work. When the smoke gets out, it stops! |
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elk1984 Senior Member  Joined: 11/07/2020 Location: United KingdomPosts: 232 |
Very nice. Are these available premade in the UK (or as a shared project on the PCB manufacturer sites)? |
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Mixtel90 Guru  Joined: 05/10/2019 Location: United KingdomPosts: 8564 |
It's one of matherp's. Linkey here. Mick Zilog Inside! nascom.info for Nascom & Gemini Preliminary MMBasic docs & my PCB designs |
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| ville56 Guru Joined: 08/06/2022 Location: AustriaPosts: 393 |
found this on Amazon ... maybe this could solve the issue HDMI audio inserter 73 de OE1HGA, Gerald |
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| Grogster Admin Group Joined: 31/12/2012 Location: New ZealandPosts: 9877 |
MP3 playback is SLOW, and interrupted with pops and clicks. WAV is fine. WHAT MP3 FILE COMPRESSION PROTOCOLS(bitrates etc) ARE SUPPORTED BY THE DAC/MMBASIC on the 2350B CHIP? I am working on making a sample video so I can post it here. Perhaps some bitrates are NOT supported? Smoke makes things work. When the smoke gets out, it stops! |
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| Grogster Admin Group Joined: 31/12/2012 Location: New ZealandPosts: 9877 |
It seems......... Smoke makes things work. When the smoke gets out, it stops! |
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| Grogster Admin Group Joined: 31/12/2012 Location: New ZealandPosts: 9877 |
......not all SD cards are equal. Copied the MP3 files to another SD card, and they are ALMOST perfect. First card was a 128MB(yes, MB) uSD card for experimentation, formatted as FAT32. Copy rate was about 2.6MB per second, so I thought it would have no trouble reading MP3 data. Seems not. Next test was 8GB ADATA, also formatted as FAT32. No pops or clicks on playback with this one, but still the OCCASIONAL skip, in the order of about 200ms or so of skipped audio output. IS THERE A RECCOMENDED MINIMUM SD CARD SIZE AND SPEED for use with this unit? As I say, WAV playback is FLAWLESS(even from these same cards), but mp3 is a bit "Jittery" at times. With the size of SD cards these days, there is no reason to NOT use full uncompressed WAV files, I guess!  Smoke makes things work. When the smoke gets out, it stops! |
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phil99 Guru Joined: 11/02/2018 Location: AustraliaPosts: 3015 |
Try a high CPU speed. Decompressing MP3s requires a lot of processing. Doing it in real time may need more speed. Edited 2025-12-30 17:30 by phil99 |
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| dddns Guru Joined: 20/09/2024 Location: GermanyPosts: 750 |
I own two PGA2350(A2) and experienced the same as well as other errors with devices connected to GPs higher than GP29. Especially with SD cards. If you have a spare SDcard interface try to set it up on the external I/O using some GPs in the range 0 - 7 I tested several MP3s encoded with 192Kbit and they play and sound good without any clicks or delays |
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| Mixtel90 Guru Joined: 05/10/2019 Location: United KingdomPosts: 8564 |
If SD cards are set up on ordinary GP pins with all pins specified they are bit-banged IIRC. If you put them on SYSTEM SPI and only configure the CS pin they run on hardware SPI, which is faster and more efficient. This may well make a difference when accessing mp3 files from them. I don't know this particular board, but I assume that Peter will have used hardware SPI for the SD card. . Edited 2025-12-30 19:29 by Mixtel90 Mick Zilog Inside! nascom.info for Nascom & Gemini Preliminary MMBasic docs & my PCB designs |
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| Grogster Admin Group Joined: 31/12/2012 Location: New ZealandPosts: 9877 |
I'm just using the default setup, which is 640 x 480 @ 252MHz. I would have thought that 252MHz was PLENTY fast enough for decoding MP3 data. It would not be the first time I was wrong, though, if that is not actually the case! I'm going to try some more files tonight, but just changing to the 8GB uSD card, made a big improvement. Smoke makes things work. When the smoke gets out, it stops! |
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| dddns Guru Joined: 20/09/2024 Location: GermanyPosts: 750 |
Only for you, I dug up my 2350B(A2) and set it to 640@252MHz It plays just instantly without delays or cracks with standard PWM output. My test tunes were "Crazy train" by Ozzy Osborne and "Staring through my rear view" by Tupac encoded with 192Kbit > option list PicoMiteHDMI MMBasic USB RP2350B Edition V6.01.00RC22 OPTION SERIAL CONSOLE COM2,GP8,GP9 OPTION FLASH SIZE 16777216 OPTION COLOURCODE ON OPTION KEYBOARD US OPTION PICO OFF OPTION RESOLUTION 640x480 @ 252000KHz OPTION SDCARD GP10, GP2, GP3, GP0 OPTION AUDIO GP6,GP7', ON PWM CHANNEL 3 SDcard is a 32GB SanDisk Ultra 40MB/s Edited 2025-12-31 23:19 by dddns |
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| matherp Guru Joined: 11/12/2012 Location: United KingdomPosts: 10965 |
The board should play mp3 perfectly with no problems using the default config OPTION RESET HDMIUSBI2S I typically use 16 or 32GB Sandisk Ultra class 10 cards |
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| Grogster Admin Group Joined: 31/12/2012 Location: New ZealandPosts: 9877 |
I will try a 16GB card. Playback was much better last night - only the very occasional "Skip" in playback. The files I chose, were files downloaded from when Napster was a thing, but it is LONG gone now, so I will try some other files. All the Napster files are 128kbps Stereo, which was kinda the standard for MP3 files back then also. Now, if I need to make MP3's, I always encode at the 320kbps maximum. With drive and flash-disk capacities being so huge now, it make little sense to squish them down to save space. I'll collect some 320kbps files and 192kbps files together on a 16GB uSD and try those. My guess is that earlier MP3 encoders were not the best, so there perhaps could be an issue there. Modern MP3 CODEC's are about as good as MP3 can ever be, and FLAC and other high-quality formats have just about replaced MP3 anyway. @ matherp: Can you state ROUGHLY what %CPU is used, to decode MP3 data? Just curious as to if this is a big deal for the CPU or not with respect to the 2350 chip. The higher clock rate is needed to do the DVI over HDMI, so perhaps there is not much left over for something like MP3 decoding if you are also using the HDMI output..... WAV files play flawlessly, cos I guess this is just streaming uncompressed audio data directly to the DAC, which is probably effortless as far as the CPU usage is concerned. But MP3 requires that intermediate decoding step, and maybe that is stressing things. Smoke makes things work. When the smoke gets out, it stops! |
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| Grogster Admin Group Joined: 31/12/2012 Location: New ZealandPosts: 9877 |
Testing tonight, has revealed there is ZERO issue with the board. The old Napster files seem to have degraded, resulting in the audio pops and clicks. I can 100% reproduce this, if I play back the same file on Linux or even Windoze. The pops and clicks are at EXACTLY the same point. I now need to eat a little humble pie, for accusing the board as the possible source of the problem.  Sorry, Peter.....  I only used the old Napster files, as I thought it would be nice to hear some of those old songs again. I tried some new MP3's tonight, including Dire Straits - Follow Me Home(from the Communique album), to test the LF response, and was blown away with how good it is via the I2S DAC chip. ALMOST literally blown away, as the volume was up there..... Superb. Smoke makes things work. When the smoke gets out, it stops! |
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| ManiB Senior Member Joined: 12/10/2019 Location: GermanyPosts: 141 |
I love the CMM2G2V2 because it's so incredibly fast and has the Raspberry Pi-compatible I/O connector strip. But the PicoMite2 is clearly more modern, and yes you are right - it's cheeper, too.   Edited 2026-01-01 19:49 by ManiB |
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| Mixtel90 Guru Joined: 05/10/2019 Location: United KingdomPosts: 8564 |
You want audio over HDMI to horrible built-in monitor / cheap TV speakers? ;) TBH I much prefer decent headphones to any speakers, simply because I'm almost deaf in one ear and speakers of any sort just don't work well for me now. The CMM2 PCB would probably have been a lot cheaper if it hadn't been for the awkward cutouts for the WII connectors. The problem there is availability of the correct connectors as they don't seem to have been manufactured in quantity for decades now, the available ones may even be NOS. Edited 2026-01-01 20:20 by Mixtel90 Mick Zilog Inside! nascom.info for Nascom & Gemini Preliminary MMBasic docs & my PCB designs |
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| Volhout Guru Joined: 05/03/2018 Location: NetherlandsPosts: 5703 |
Hi Mick, I use the TV HDMI to convert HDMI audio to optical, and run the optical audio to my old Harmon Kardon amplifier. With a set of 1 meter high speakers, sound will deafen your ears...and you may even hear it with BOTH ears. Tip : Dire straits : Telegraph Road. PicomiteVGA PETSCII ROBOTS |
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| Mixtel90 Guru Joined: 05/10/2019 Location: United KingdomPosts: 8564 |
Nice. :) I haven't got room for my "vintage" B&W DM4s and Crimson amps in here. lol They are plenty loud enough but that doesn't restore audio direction identification so I don't hear stereo. At least headphones restore some of that (with judicious use of a Balance control). Mick Zilog Inside! nascom.info for Nascom & Gemini Preliminary MMBasic docs & my PCB designs |
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| Volhout Guru Joined: 05/03/2018 Location: NetherlandsPosts: 5703 |
My previous speakers where B&W DM5's. Loved them, but they aged and I needed to replace speakers. Then opted for new. Volhout PicomiteVGA PETSCII ROBOTS |
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