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Frequently Asked Questions

These are the most frequently asked questions.
Here are some less frequently asked questions.

What Hard Drive Sizes Are Supported?

The firmware can access up to 128 gigs (the 28 bit LBA limit).

FAT32 formatting is required. With Microsoft's utilities, you generally need at least 500 megs to use FAT32. It is theoretically possible to go down to 256 megs using special formatting utilities (the minimum cluster size supported is 4k, and FAT32 requires at least 65525 clusters).

The 0.6.10 firmware scans all the directories at startup to build a list of all the files. The speed is approx 120 files/second. I recently made some improvements that get this to 140-150 files/second, and my hope is to eventually make it must faster. If you load up an 80 gig drive with 16000 five megabyte MP3 files, you'll wait approx 2 minutes for the initial scan. So today's directory scan speed put a bit of a practical limit on the number of files you can reasonably have on the drive... depending on how patient you are.

What Parts Do I Need To Make This Thing Work?

Unlike an off-the-shelf consumer product, this board can be used in many possible ways. The exact parts you use depends to some degree on what you intend to do.

Most people use the assembled circuit board and the 24x8 LCD. The LCD is optional, but many features are only accessible from the LCD. You also need a hard drive, IDE cable, power source, headphones or amplifier to receive the audio output, and a case or some other way to mount all this stuff.

It is easiest to use a 2.5 inch laptop drive. Laptop drives use a different cable than standard 3.5 inch drives. You need to power the board. Most people use 12 volts. If you have a 12 volt power supply (usually 8-10 watts or more), you can probably use it. We sell one that works with the board (USA 120Vac power). Many people eventually power the board from 12 volts in a car, which is fine. There is also a lower voltage input that can work with 4 or 6 AA-size NiMH or NiCd batteries (6 cells gives much better performance than only 4).

You can also use a 3.5 inch drive. This is cheaper, and many people have an extra 3.5 inch drive in their spare parts from previous computer upgrades. With a 3.5 inch drive, you also need to provide power to its 4 pin connector. The 2.5 inch drives do not require any sparate power source. The little power supplies from external USB or older SCSI drive enclosures work fine if you run from AC. For use in a car, it's rather difficult to power the 3.5 inch drive. It's virtually impossible to use 3.5 inch drives with AA size batteries.

If you want to upgrade the code for new features or hack on the code yourself, a serial cable is needed. The serial cable also allows you to see much more info for troubleshooting.

One final, optional thing is either a removable drive bay or USB-IDE adaptor. These make it much easier to remove the drive and put it into your PC to copy files.

What Type/Size SIMM Can I Use? Can I use a DIMM (SDRAM, DDR)

Most, but not all 72 pin SIMMs will work. The design supports up to 32 megabytes. Speeds from 50 to 80 ns work, and it does not matter if the memory is EDO or FPM (fast page).

The board will also work without any SIMM at all, but it will run the old 0.1.3 firmware which has only minimal features.

The circuit board was designed for the original Micron SIMMs. In recent years, SIMM formats have changed. Most of these will work with the latest firmware revisions, but at a reduced capacity. There is no simple way to identify the SIMM format, but you can read this lengthy explaination of the technical details.

168 pin DIMMs will not fit into the 72 pin SIMM socket. There are no plans to change the design to use a 168 pin DIMM socket. The DIMM socket is longer, and would result in a longer circuit board. The large number of pins would also require using a fine-pitch surface mount chip, instead of the hobbist-friendly 84 pin PLCC Xilinx FPGA (which has just barely enough pins to work with a SIMM). If you don't have a SIMMs, we usually have some used SIMMs in stock. We test these SIMMs with the player to make sure they are compatible.

Are the boards still available, and when can I get one?

Yes, we still are providing boards. The main product list page is regularily updated with the inventory status.

Usually we are able to ship orders made with a credit card on the next business day after we receive the order. Other payment options add some delay, and if you are mailing us a check or money order, we need to wait to receive it.

Can you add USB for easy loading of the files?

Cheuk Poon successfully added USB to his player. Check out his page in the photo gallery.

We're hoping he will provide more details for others who want to attempt this. Following PJRC's privacy policy, we haven't posted his email address (we're hoping to do this soon if he says it's ok)... but if you are serious about adding USB, we can forward your email to him.

What about a backlight for the display?

Currently Techknowman has kits for adding a backlight, as well as several other pretty illuminated components. Some work is need to add the backlight to the LCD. Several colors are available, and the blacklight inverter (power supply) can be ordered in different voltage inputs (though 12 volts is the most common).

We are working with Techknowman to offer his backlight LCD at the PJRC store, already assembled and ready to plug in.

Previously, LCD conversion kits were provided by Dean Woodyatt, but saddly he ran out of EL sheets and stopped making them. His site still has useful information and a nice step-by-step instruction page.

Do you have a case to put it into?

Currently there is no case available for the player. Many people have created some interesting cases for their players, and some have sent us photos which you can see in the User Photo Gallery.

Also, a regular topic in the User Discussion Group is ideas and plans for cases.

How do I select the file I want to play?

If you have the 24x8 LCD, there are four buttons you can use to select files:

  • Next Directory
  • Previous Directory
  • Next File
  • Previous File
Using these buttons, you can move between directories on the drive, and then move to the file you want within a directory.

Some work has been done in the firmware to create an interactive "tree list" type file selector. This is a work in progress (mostly due to hard work from Tom and Matthew). If you're interested in hacking on the firmware, this feature needs you!

If you use the board without the display, there are only buttons to move to the next and previous file. Directory navigation requires the LCD.

Can I use a CD drive instead of a hard drive?

Marco Bakker has written ATAPI support, but has yet to be integrated with the rest of the project.

Some time ago group of students undertook a project to add ATAPI support to this player. They had some partial success. Here are seven pages they wrote about their project.

ATAPI CDROM drives use the same signals as IDE disk drives, but the communication protocol is different. They also use a different filesystem, ISO9660 instead of FAT32. All that is needed to support ATAPI CDROM drives is code in the firmware to use the ATAPI protocol and the ISO9660 filesystem code. When this firmware is available, it may be loaded onto existing boards to make them read CDROMs as well as hard drives.

I connected my board and nothing happens, now what do I do?

This troubleshooting page is still under construction, but it does have quite a bit of information that can help. Nearly all troubleshooting requires connecting a serial cable to view the messages that the firmware prints as the board boots.

The most common problem is inadaquete power provided to the board. The 12 volt input requires a DC voltage between 9 to 16 volts. If a laptop drive is used, the current rating should be at least 800 to 1000 mA. The low voltage input is intended for NiCD or NiMH batteries. Again, a laptop drive will consume considerable power while it's motor is spinning up to full speed.

When the board does fail, the Xilinx XCS10XL chip is usually the first chip to "blow", and it usually fails in a short-circuit manner that tends to protect the other chips on the board. Failures are usually caused by a higher voltage momentarily shorted to the 3 volt power lines on the board, or to the IDE connector pins.

I want to remotely mount my own pushbuttons.

It is not necessary to remove the pushbuttons that are already on the board. The buttons on the board are normally open momentary contacts. You can wire additional normally-open momentary contact pushbuttons in parallel with the ones that are already on the board. All six pushbuttons are connected to ground, so with a little investigation you should be to use 7 wires instead of 12.

For really long wires (over 6-12 inches), it's a good idea to add a small resistor in series with each line, soldered close to the board. While not absolutely necessary, this will help protect the board is the event that one of the wires shorts to, say, a 12 volt power line. 1K resistors would be a good choice.

TODO: LCD pushbuttons exist now (the answer above was originally written before the LCD/pushbuttons existed)... add info about extending the cable length. In a nutshell, you can easily extend the 4 conductor cable to mant feet (a few meters), or perhaps longer with special wires. The red and black lines should use 18, 16 or other heavy gauge wire to avoid losing voltage needed by the LCD circuitry.

When will feature XXX be ready?

It's very difficult to predict the future, particularly when it comes to software development. The best thing to do would be to make sure you're on our MP3 player announcement mail list. We send out very few messages. It's really only to announce major changes and substantial new features. You'll know as soon as we have new firmware with the features you want. If you want to keep up with development and discuss the player with others, you can join the Yahoo Discussion Groups.

Now it's true that this answer has dodged the question, but we really are avoiding making promises about when particular features will be ready. You could read through the recent news page and development history page to get an idea of the general pace that this project has.


Didn't find the answer to your question....
Try this list of less frequently asked questions.


MP3 Player, Frequently Asked Questions, Paul Stoffregen.
http://www.pjrc.com/tech/mp3/faq.html
Last updated: February 23, 2005
Questions, Comments?? <paul@pjrc.com>