Have a question about multimedia or audio? Ask our Expert, Ken Boyce

Hello Alex,

Unfortunately I do not have any product based experience with the BU9458 or BU9457 devices from Rohm.  Nor do I know of a commercial product on the market that uses them.

Also, it appears that the datasheets for those devices do not offer much info on any application circuit.  So I can't really judge very well a potential product design based on them.

However, the basic idea of the parts is good in that you have both SD card and USB (flash memory drive) as input sources for the formatted audio material.  Also, a key advantage is that the part can operate self contained as a decoder or can be controlled via an external processor/micro-controller.

My direct experience with an MP3 player design was one involving a PIC microcontroller + an MP3 decoder which in turn was controlled by a larger CPU running a complex system that happened to need audio at various operations.  That design used a standard SD card with very simple file naming structure which may not meet your needs.  If you want more info on this, let me know.

Ken

Hi Alex,

Thank you for updating me on your project.  I am glad it has worked out well for you.  It would be great if Rohm improved their data sheet content.

Kind regards,

Ken

Hi Aleksandar, I'm trying to understand the "access data" too.

Chould you kindly specify the sequence of commands to extract directory/files names ( in mode3 )?

For example:

- how to read the name of the first folder (It shold be the root folder)?

- how to read the name of the first file in the first folder?

- how to read the name of the second file in the first folder?

...

- how to read the name of the first file in the second folder?

- how to read the name of the second file in the second folder?

...

- how to read names of subfolders too?

Regards

Davide Fabbri

Ha-ha... those are exactly questions which I had before I find the solution. And this just proves that definitely there is a need for more information to be added to PDF files about BU9457X.
I will not surprise if you all ready find one for yourself. But if you did not I will provide you more information.

I am working on MP3 player with microchip graphic TFT solutions and PIC 32. I also using mod 3 for BU9458 (BU9457 and BU9458 are equally good and no software need to be changed, hardware is the same as well).

What I will explain here I do not claim that this is the very best solution (as there is not documented that this is the right way how need to be done but its work perfectly and I strongly suspect that this is idea of designers of BU9457x how to control BU9457X in order to play right MP3 file.

If you find better solution please let me know although as I say this solution working perfectly well for me.

1. Very first you need to use command SET DIRECT and access code, should be 0, 0, 0, 0, 0, 0.
(All binary zeros not ASCII).

2. Then use GET DIRECT

3. Then use READ FILE INFO command

4. Then use READ BUFFER from 20 (think as memory location 20 hex and it is called COMAREA)

Now use access code which you get from process in steps 3. and 4.. You can find access code information from buffer comarea and use this access code to SET DIRECT in next step.

5.SET DIRECT ( StatusOutputOffset[25hex}, ...24,23,22,21…;StatusOutputOffset[20hex])

You are ready for first MP3 to play, by setting command PLAY DIRECT.

6. PLAY DIRECT  this will start the music (if you all ready have your SD or USB files with MP3)

That command will play very first MP3, but what if  you don’t want to play very first song?

Then you need to repeat steps 3. Then 4. N times in case that your song is song number N.

But how to be sure that song number N is the right one?

Just repeat 3. (Read file info) and after 4. ( Read buffer comarea from 20 hex)

You have information in comarea about name of the song (MP3 file). If this is right one just set command play if not continue to repeat steps 3. and step 4 read until you get right one.

Now there is more then that. For example you need to wait that BU9458 is available by checking status 1 , 2, 3 etc to confirm that BU945X is analyzed all and is not busy, that BU945X has recognized USB or SD but I recommend at first stage to simplified all by using loops of 10 ms so you can avoid to read STATUS 1,2,3 etc between each steps.  When you have mastered control over BU945X then you can add more improvement (for start use even more then 10 ms, 100 ms will ensure that between each step (commands) are more then enough time and is definitely long enough for all internal processes inside BU9457X so you can use what I explain and without checking STATUS 1,2…

If all of that is not working for you probably you having problems with I2C communication.

Any way I can send you my C code (give me your e mail), if you promise that you will not laugh on my code, but don’t forget…. my code works

Best Regards Alex

Thank you very much Alex.

Your description is crystal clear. After the call to SET DIRECT 000000, GET DIRECT, need call READ FILE INFO repeatedly to scroll all files.

It would be great if you could send me your C code at: element14 at davidefabbri dot net ( No laugh, I swear )

Davide Fabbri

Definitely I should be politicians!

Later one I will send you source code.

     Best Regards Alex

!!!!!!!!!!!!!!!!!!!!!!!!

!  Alex for President  !

!                      !

Thank you for sharing your code ( and your schematic ), now I have a good ( and working ) starting point.

The project is an 'mp3 player for armchairs': a client of us produces relaxing/massaging armchairs, and he want to add this function to his armchairs.

The player should have an usb input ( so each one with an usb memory could listen to his favorite music ).

Two versions are planned: a 'dumb version' ( with no display ) and a 'smart version' ( with grafical display ) and bu9457/8 addresses both versions.

P.S. oddly enough rohm applications for bu9457/8 already knows of this strange use ( as an mp3 player for armchairs ), the image is from rohm site

Hello
Can you help me I'm not getting the folders view.

Hello
Can you help me I'm not getting the folders view.

Leonardo,

I am sorry but I don't understand your question.

Ken

Sorry,
Can you help me?
How to access folders on BU9458 check the total amount of music.
Thanks

Hi Leonardo,

I could not find a data sheet for the BU9458 on the ROHM website.  However, I did find one here:

http://pdf1.alldatasheet.co.kr/datasheet-pdf/view/349375/ROHM/BU9458KV.html

As  usual with Rohm data sheets, there is very little information.    However, there is a statement that a FAT analysis function is contained   in the part.  What that means to me is that it can check that the SD   card that can be interfaced to it is in the FAT32 format or not.  But  the data sheet does not give any indication what the function does.  The  function  may be able to tell you used/available memory space, but the  data sheet  does not indicate such a thing.

My guess is that the part does not allow getting the information you want, although only Rohm can answer that question.

There is also information about a BU9458 demo system at the following URL:

http://krisbahar.com/online_work/demo_eval_code_rohm_bu9458_&_oki_ml610q412_v01_2010-08-11.pdf

The article has some info about Folder operations, but it is limited to   simply choosing the folder, and the song in the folder.  Nothing about   Folder space usage.  Look at pages 21, 22.

The source C code for the demo is at the end of the article.


Perhaps you could contact Rohm and pose the question to them.  Someone   else may have also asked the same question.  The author of the article   is Kristopher Bahar, and his website is:

http://krisbahar.com/  and his email address is krisbahar@gmail.com.

Sorry I cannot be of more help.
Ken