Dev board as a mainboard?
  • Hello everyone!

    I'd love to build an "all protoboard" version of the lxr, but I had some doubts regarding the mainboard.
    The idea was to use a cheap stm32f407 development board to avoid smd soldering,
    but I noticed a few differences between the mainboard schematic available on the assembly instructions page and the new version of the board.
    I was wondering if someone knew it was the same board without the ADC or if there were more changes..
    Is the new schematic available anywhere here?

    I found on ebay some cheap dev board (10bucks) that already offer usb connection, sd slot and 8Mhz crystal.. it would only be a matter of adding the dacs!
    Another doubt on the chip: stm32f407vet6 has 512KB of flash instead of 1MB (vgt6 version), would it be enough or should I search only for the vgt6?

    Thank you all in advance!!
  • The LXR was first developed on an stm32f407 discovery board (~10-15€)
    But the TOS is quite restrictive and I would not have been allowed to redistribute the boards.
    Then I decided to move to my own design and added multiple audio outs and the SD card socket.
    The discovery board had only a single audio out.

    So in general it works, but the code has to be changed a bit.
    I'd have to take another look at the source, but the driver for the discovery board DAC might still be in there.
    But it is definitely not a "plug'n'Play" solution.

    512kb flash is enough, the rest is only used as sample memory on my boards (which is a crude hack anyways ;) )
  • Thank you for your answer!!

    The discovery board I found is a chinese unbranded breakout board and offers no audio out..

    Like these ones..
    Your board uses 2 internal dacs and 2 external CS4344 to offer 4 audio outputs, right?
    Adding 2xCS4344 would replicate that configuration, why would be necessary to modify the code?
  • this is the one i used before

    This board only has a stereo out.
    On the LXR board I use 2 external DACs to provide the 2 stereo/4mono outs.

    So if you add the DACs to whatever dev board you use you don't have to modify the code, but you are back to a custom PCB layout for the SMD parts then.
  • Happy to hear that!

    I was planning to simply make a dac shield (protoboard) with those CS4344 mounted on SOP to DIP converters, to avoid producing a new pcb.
    The ADC section with selection jumpers is no longer necessary, is it?

    Thank you for your support!!
  • ah ok, that's an option.
    no jumpers are not necessary anymore.
    The first boards had an ADC option with the idea to re-use the board for other projects, but in the end it seems more economic to me to make dedicated boards.
  • Thank you very much Julian! You are the man!!
    It's going to be good fun building it from scratch :D

    Have a nice day,

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