a low-price micro STM32 to read .mp3 file from SD Card ?

[MBertocchi]

Hello friends,
I write this post to ask for a hand in choosing a low -price micro stm32 that can read an .mp3 file from an SD card. The customer wants a really low cost and therefore I cannot go to use microcontroller with 100 pins, but I have to use a really cheap micro that gives me the opportunity to read a .mp3 file from SD. I ask for your willingness to help me!

[Andrew Neil]

Just read it?

Just reading files from SD Cards can be done (and has been widely done) on simple 8-bit microcontrollers - so (pretty much) any STM32 will be able to do it.

At minimum, all you need is an SPI port.

http://elm-chan.org/fsw/ff/

 

[MBertocchi]

thank you friend, take a look at what you forwarded me

[QSHAO.1]

If a SPI port is not enough for your application, you may need a SDIO interface on your STM32.  Anyway, you may install App STM32 Finder from STM32-FINDER - STM32 product finder for mobile devices - STMicroelectronics, and select right MCU for your application.

[Andrew Neil]

The "MCU Finder" is also available for Windows/Mac/Linux:

https://www.st.com/en/development-tools/st-mcu-finder-pc.html

[Ozone]

As pointed out, reading a file (.mp3 or otherwise) is pretty pointless as such.
More important is, what you want to do with it.
The request suggests you need a MCU capable of decoding MP3, and feeding it to an audio amp.
I'm not sure if small and cheap 8-bit MCUs would suffice for this use case.

OTOH, I haven't dealt with MP3 encoding/decoding yet.
You might need to experiment with M0/M0+/M3 cores to check your performance requirements.
File reading (SPI/SDIO) and serial audio data output (SPI, I2S) are relatively light on pin count, you can get away with small packages.
You only need to make sure every interface you need is routed to the available pins, and all interfaces are routable simultaneously.

[MBertocchi]

can you tell me exactly if I should use SPI or SDIO? I chose the µ STM32G431KBU6 which reads the .mp3 file and translates it into a DAC value with low precision

[Andrew Neil]

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@MBertocchi wrote:

can you tell me exactly if I should use SPI or SDIO? 

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That's entirely up to you - use whichever fits best with your particular project requirements!

[LCE]

And another thing:

So you read an mp3 file from SD-card - that's all you told us until now.

Be precise in your requests...

So you also want some audio output - but don't forget that inbetween file reading and DAC output you must decode mp3 data to something a (probably very cheap, or even the internal) DAC can understand.
So better check for some libraries for decoding, and which STM32 can handle that.

[Andrew Neil]

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@MBertocchi wrote:

 really cheap 

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If that's your key concern, note that there are cheap chips & modules which do SD-Card MP3-to-audio direct; eg,

https://www.aliexpress.com/item/1005005212215899.html

https://www.amazon.co.uk/DollaTek-Lossless-Decoders-Decoding-Amplifier/dp/B07M6JWMH6