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Forum Index : Microcontroller and PC projects : Just for Javavi to play with. I2S audio on the RP2350
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| matherp Guru  Joined: 11/12/2012 Location: United KingdomPosts: 10230 |
I said I wouldn't but then it looked like an interesting challenge  RP2350 only - uses PIO2 .program i2s .side_set 2 ; BCLCK and WCLCK output (2 bits) public entry: .wrap_target ; wrap jump target set x,30 side 0; pull noblock side 1; dataL: out pins,1 side 0; jmp x-- dataL side 1; set x,30 side 2; pull noblock side 3; dataR: out pins,1 side 2; jmp x-- dataR side 3; .wrap ; wrap jump to .wrap_target Test version is standard PicoMite PicoMite (2).zip OPTION AUDIO I2S BCLKpin, DATApin This reserves BCLKpin and BCLKpin+1 for the bit clock and word clock and Datapin for the I2S data. It requires an I2S DAC that can PLL the bitclock to create its own master clock For example: OPTION AUDIO I2S GP1,GP5 GP1 is the bit clock GP2 is the word clock GP5 is the data pin All normal audio should work TONE, MP3, FLAC, WAV, MOD, SOUND Note that you will see jitter on the BCLK. For the CPU at 150MHz the PIO needs to run at 44100*128 = 5644800 = 1/26.57 of the CPU clock speed. The way the H/W does this is to add or subtract clock ticks to the length of the PIO clock to give an average of 26.57 CPU ticks per PIO clock - hence jitter.  PLAY TONE 200,400  Edited 2025-01-21 02:20 by matherp |
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javavi Guru Joined: 01/10/2023 Location: UkrainePosts: 458 |
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| javavi Guru Joined: 01/10/2023 Location: UkrainePosts: 458 |
Thank you very much, you made me happy! [  My board with the soldered TDA1387T I2S DAC chip is now playing good music loudly! And it doesn't matter whether the neighbors like it or not! |
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| ville56 Senior Member  Joined: 08/06/2022 Location: AustriaPosts: 220 |
@javavi: At what cpuspeed are you running the setup? I've just made a setup with a PCM1502 chip (seems to be the same board as Peter is using in the foto of his setup) on an Pimoroni RP2350-plus and encountered some strange effects: at e.g. cpuspeed 252000 kHz and MP3 playback i get clicking noise and a "phasing-like" effect between left and right channel. Makes me dizzy with headphones and almost hurts my ears.  at cpuspeed 206000 kHz the sound is audibly less distorted as far as i can tell. Minor fast clicks are audible though. The clicking can also be reproduced with play tone command, but not the phasing effect. That appears only on mp3 playback. Are there any restrictions to the mp3 compression used? Is the TDA1387T showing the same effects? MMBasic Version is V6.00.02.b3 73 de OE1HGA, Gerald |
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