Replies: 13 comments 19 replies
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One thing I noticed is, I'm not sure it's due to Cortex-M7's pipeline latency, or SAM E70's bus matrix inefficiency, it's very slow to access non-cached memory. I test the speed by copy data from internal SRAM to external SRAM interface: With DMA I can always get the maximum throughput because it do burst access. As generally USB FIFOs are not cached, I think we have to add DMA support in order to handle high-speed transfer properly. @hathach Do you have any experience about this behavior on Cortex-M7 ? |
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@HiFiPhile I haven't worked with SAME70 just yet to comment, though on iMXRT 10xx which is also M7, you need to Invalidate mcu cache for peripherals to pick up https://github.com/hathach/tinyusb/blob/master/src/portable/nxp/transdimension/dcd_transdimension.c#L47 . The slow thing probably is due to SAME7x clock, memeory configure or else, I think you will have an better anwser asking in Microchip forum. |
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That's crazy fast :D Yes please share some details, i am always interested in fancy stuff ;) Do you alreaey use your XMOS replacements in an audio project? |
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I've only done some simple tests the MCU+FPGA combination, including configuring the FPGA by MCU and high-speed communication. Currently I'm making a board of SAME70+ICE40HX8K, which can be used as a multi-propose development board or a I2S-bridge. Strangely there are few boards of MCU+FPGA, and most of then can't do high-speed streaming.
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That looks pretty nice! But you skip the mounting holes? Do you have any case in mind? |
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There are SMD spacers on the bottom :) As it's pretty small, I think it's more practical to plug on mother board, for example plug on the DAC board when used as an I2S-Bridge. (Pin headers mounted on the bottom)
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Ah well thats a good idea! How many layers do you use? 4? |
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Yes 4. At first I was think using 6 layers to fanout all signals, but it turns out 6 layer PCB is still expensive 🤣 |
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I have never used SMD spacers but don't they ned a hole too? |
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Some spacers need hole, this one doesn't. Wurth has a complete line of spacers. https://www.we-online.de/katalog/datasheet/97730606330.pdf I use JLCPCB, and PCBWay/PCBGOGO for PCBA. |
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@PanRe I've received 5*PCB half assembled for 35€ :) |
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Wow nice! :) Thanks a lot for the offer! Hardware is always welcome! :D But don't you want to test it in advance? ;)--Diese Nachricht wurde von meinem Android Mobiltelefon mit GMX Mail gesendet.Am 16.02.21, 16:22 schrieb HiFiPhile <[email protected]>:
@PanRe I've received 5*PCB half assembled for 35€ :) If you are interested I can "sponsor" you one.
—You are receiving this because you were mentioned.Reply to this email directly, view it on GitHub, or unsubscribe.
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Finally I finished 2 PCBs :) At least USB bootloader works. |
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It looks pretty nice! Let me know how it works! :) |
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Test goes pretty well :) I've just published some documents: |
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I was wondering how your project is going on? Are you fine with the current audio driver and does all work as you whished for? :) |
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Honestly I didn't make much progress 😂.... Maybe I need a vacation to regain motivation 😅 I think the audio driver is in good state, I also added fifo support for same70 but not haven't tested yet. |
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That is very kind of you but currently i am also lacking time to do anything 😂. |
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Finally I switched to LPC4322, with the flexibility of SGPIO I no longer need the FPGA. I made a board with Si5332 as clock generator for MCLK & BCLK, a 74AUP2G79 D Flip-Flop for LRCK & DAT signal shaping. It works pretty well, in theory I can go to 32bit/768kHz but Windows driver only does 32bit/384khz :) Here is PCM5100 trying to output a square wave of 192kHz :) |
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I've also considered LPC55 but it's I2S peripheral is too slow to handle high data rate. I think the SGPIO of LPC43 it's the only peripheral capable of sampling external clock more than 50MHz. |
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ah right, apparently you have even other peripheral requirement as well. Thanks for sharing. |
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Finally I've added SPDIF software encoding :) LPC43xx with SGPIO is a powerhouse, at 24bit/192kHz total CPU usage is about 40%. (A bout 10% without SPDIF)
Video is playback demo with my DAC. wx_camera_1628359052889.mp4 |
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🎵 🎵 Great to hear you get it working. SGPIO is great, raspberry pico PIO is quite similar (not entirely sure since I don't look deep enough at the two) but got lots of attention from public. Poor NXP, they should do a better marketing/documenting for the peripheral 😄 |
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Yeah the whole lpc43 line is poorly supported, no LPCxpresso configuration, library is quite old. On i.mx RT there is a shifting register who does similar work like SGPIO but it has slower bus speed (120M vs 204M) despite a much quicker core. |
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That really sounds quiet nice! Sorry for responding so late, i was moving into a new flat which turned out to be quiet time consuming ^^ |
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Congrats for your new apartment 🎉 |
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@PanRe Congrats to your new 🏠 🎉 🎉 |
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Thanks guys 😄 |
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I am tired from just barely cleaning my own desk. Moving out, I am not sure how long would it takes, nah never mind 😅😅 |
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It is astonishing how many little crabby stuff you collect over time 😄 |
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@PanRe
My idea is to replace XMOS ICs, while they work great sometimes it's hard to buy, and I like a more universal solution.
Instead of using MCU's I2S, with a little iCE40 FPGA I can have native DSD output, auto mute on empty FIFO and some crazy (mostly meaningless) stuff like PCM 768K and DSD1024.
On SAM E70 with a 16 bit SRAM interface I got a throughput about 70MB/s :)
If you are interested I can share you more details 😎
They are very limited STM32s with internal HS Phy, they are either too big (144pin LQFP, which occupy more than 3*3cm) or too expensive to make the PCB (most low-cost PCB factories can't do 0.65mm BGA)
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