MicroSD Memory Card Transport Project

[Bunpei]

Originally posted by EUVL
1) What size of SD card can your solution support ?

Chiaki's firmware only supports FAT16 and the upper size limit is 2GB.

Originally posted by EUVL
2) How about user interfaces -- control buttons, display, remote control, .... ? I only see 2 push buttons on the first photo.....

Three buttons and one blue LED are prepared for the purpose.
Chiaki developed his original human interface of three modes using these devices. Three modes are
1) single file playing mode
2) file selection mode
3) folder selection mode

[EUVL]

Would be real nice if it can support FAT32 and a bit bigger memory size, say 32GB. I am not sure how long 2GB SD cards would still be available. These days you can hardly get any USB sticks under 2GB, and I am sure they would also extinguish in a few years' time.


Patrick

[Bunpei]

Originally posted by EUVL
Would be real nice if it can support FAT32 and a bit bigger memory size, say 32GB.

Yes, it's important.
Chiaki and I are making a concept for the next step. My requirement is 24bit 192KHz I2S output. This means 9.216 Mbps and 550 MB/Min.
FAT32 is essential. 32bit ARM CPU or something like that will be necessary. For example, ARM LPC2388 has an I2S output.
Anyone tried programming of ARM to output I2S for 24bit 192KHz?

[prinzinio]

bumpei, what power supply have You used in Your wm8741 board?
I have the same board and i'm not sure what would be the best option to provide power fot it.

[Bunpei]

Dear Prinzinio,

In my case, first I used simple UM-01 batteies ( 1.5V x 8 = 12V, plus and minus, totally 16 pieces ). It was not good.
Now, I am tentatively using two cheap so-called "AC adapters" ( 12V 500mA , 4$/each). The result is not desperate at all. Within acceptable level.

However, if you expect "the best", it might be better for you to prepare any non-switching type regulated power supplies
with large and good capacitors.

My recommendation is to use "balanced output".
(As for WM8742 Evaluation board, XLR connectors are on-board)

Bunpei

[prinzinio]

thank You Bunpei for the answer,
I might be wrong but isn't 500ma to low to provide enough amount of power?

Probably You saw this site:
http://www.lampizator.eu/LAMPIZATOR/...WM8742DAC.html

There is written that at we need at least 30vac (30vac / 12v= 2.5A) to make good psu for this board.
I'm not a specialist, i'm just asking for Your point of view

btw. Your "ac adapter" is supplier of AC, or is it just called "ac adapter" but it gives DC on the output?

[Bunpei]

I'm sorry, an "AC adaptor" must be a Japanese English. Of course, it outputs DC from AC 100V input.

A Japanese audiophile expert presented such measurement result in a Japanese website;
- Under the condition of no load, no sound, stable state
- +12V side: 180mA, -12V side: less than 30mA

As you know, the +12V side includes all VDD and DVDD.
The net current that 2 x 2 opa2227 LSI require is not 1 - 2A order but 100-200mA order, I guess.

Another Japanese well-experienced audiofile told me that small influence of variability in +-12V power voltage for opa2227 can be understood when you read "POWER SUPPLY AND COMMON-MODE REJECTION RATIO vs FREQUENCY" on the page 5 of the datasheet;
http://focus.tij.co.jp/jp/lit/ds/symlink/opa2227.pdf
That's why the evaluation board has no internal voltage regulators for +-12V.

Bunpei

[Bunpei]

Chiaki and I made the second version using "VS1053b Proto Board"
http://www.vlsi.fi/en/support/evalua...rotoboard.html
which is provided by VLSI Solution Oy. The board is available at their webstore;
http://verkkokauppa.planeetta.net/ep...53_PROTO_BOARD

We changed and added the following three points:
1. We could obtained an "I2S output enabled" version of their "Standalone player", a EEPROM based firmware, through the courtesy of the supporting staff of the company this time. They may provide it to you if you request it at the timing of ordering.
2. Chiaki designed and made a piggy-back board for a S/PDIF output.
The board contains, Cirrus Logic 8406 Digital Audio Interface Transmitter and a pulse transformer for RCA output.
3. Chiaki replaced original crystal for 12.288 MHz with a TCXO, product of FOX.

Now, we can output to generic DACs of S/PDIF input.
However, hardware output fs from VS1053b is limited to 48kHz even if a 44.1kHz WAV file is played. That's because the board has just one 12.288MHz (256 x 48kHz) crystal.

Bunpei

[EUVL]

With all respect, I think you are making it more complicated than necessary. Other than the designs from Koon and ECDesign, there are many examples of SD Card Wave Players which all look very minimalistic, e.g.

http://www.omniboard.be/
(The Echo 2 will play WAV as well as MP3, I was told).

One thing in common -- they all use some versions of dsPIC33 family.
Maybe dsPIC33 is the right choice for the purpose ....


Patrick

[Bunpei]

Dear Patrick,

I just wanted to contact to you by e-mail.

As a matter of fact, this Proto Board version
http://www.vlsi.fi/fileadmin/evaluat...xxpp20-sch.pdf
is simpler than previous one because it has no MPU. The VS1053b codec (also a DSP) reads sound files on SD memory card by itself.

S/PDIF is somewhat redundant. But it's just a removable option.

The reason why we use 8051 architecture is that Chiaki is really an expert for the MPU (he is an author of book that explains how to programming in assembly language of the CPU. The book is written in Japanese.) He has accumulated much for it.

If you are interested in this version, you can purchase the Proto Board (80 Euro) from VLSI webstore.

Bunpei