Kitstream

Frequently Asked Questions

How do I interface the player to my car's head end unit?
Can I use a cable to extend the LCD display?
I would like to use a different LCD display. Will it still work?
What power supply should I use in a car?
Where can I get cheap laptop hard drives?
Where can I get these 2.5" to 3.5" IDE adaptors?
How can I connect the unit to my speakers?
Is there a better way of copying MP3 files to the hard drive?
How do I add Compact Flash to the unit?
Is there a limit on the number of subdirectories I can add?
Is there a limit on the largest hard drive I can use?
What is the frequency response and THD?
How can I attach a keypad?
What is required to get a working unit?
Does the decoder support variable bit rate recordings (VBRs)?
What is the expected delivery time to my country?
Why is the playback order different from that shown in windows explorer?
Where can I find a suitable enclosure?
Where can I find more information?

How do I interface the player to my car's head end unit?

This will require interfacing the player's I2C expansion control bus to the proprietary control bus of your car's head end unit. The player I2C expansion bus is explained in chapter 9 of the manual and there is an example i2c_ser PIC project which provides an RS232 output which can be interpreted by this example java application. The information and projects for the various bus protocols can be found on the web.

Can I use a cable to extend the LCD display?

Yes, but please try to keep the cable length <20cm as the signal terminations are susceptable to reflections. Above this distance, you will need to insert some extra circuitry to reduce the signal reflections (Many thanks to Tino).

I would like to use a different LCD display. Will it still work?

The player will support all PARALLEL 122x32 graphical LCD modules which use a Epson-compatible SED1520 controller, and a 20-way single-in-line connector. It is recommended to also use a module with a LED backlight. Please contact me if you are unsure if a particular module will work.

What power supply should I use in a car?

The player module itself will operate on a regulated 5VDC @ 75 mA. So its actually the hard drive that is the significant power-hungry device. I would recommend using a 2.5" notebook/laptop hard drive for cars, as they tend to be more mechanically sturdy and also run off a 5VDC regulated supply @ ~1000mA. A single 12V-5V DC-DC converter can then be used to run the whole module. The cheapest way is to get a LM7805 3-pin 5V regulator and boost the current output (with a heatsink attached). Circuit There are also some high-efficiency off-the-shelf 'brick' DC-DC converters available. Meanwell.

Where can I get cheap laptop hard drives?

The notebook drives are quite good value at ~$100 USD for 40-80GB. I've used a second-hand laptop drive salvaged from a "damaged" laptop I bought on ebay for ~$25 USD.

Where can I get these 2.5" to 3.5" IDE adaptors?

How can I connect the unit to my speakers?

The audio output is a standard line-out 3.5mm stereo jack, with an AC voltage of 1-2V. This can connected directly to the auxiliary input of most HIFI amplifiers, in place of a CD player. There are also four solder points on the PCB for 'hard wiring' audio. See the manual for more details.

Another useful gadget is an FM stereo transmitter, which can be used to broadcast the audio output from the player to nearby radios and/or HIFI receivers. This can be particularly handy for simplifying cabling, and broadcasting to nearby cars whilst driving :)

Is there a better way of copying MP3 files to the hard drive?

Yes, there are a few IDE to USB adaptors around.

How do I add Compact Flash to the unit?

The CF interface is just a minaturised IDE connector. Be sure to use a CF module > 16MB, as windows likes to use the unsupported FAT12 file system for small memory cartridges. We make a low-cost adaptor.

Is there a limit on the number of subdirectories I can add?

There is a limit of 254 'stacked' directories, which means that the unit can only remember this many directories when it is scanning for MP3 files. For example, using 4 top level directories means that there can be a maximum 250 directories in each subdirectory, totalling 1000 directories.

Is there a limit on the largest hard drive I can use?

The unit supports LBA mode FAT32 file systems, so the theoretical limit is 2048GB. Practically speaking, a 40GB hard drive should comfortably contain 5000-10000 MP3 tracks, depending on the bitrate.

What is the frequency response and THD?

This is mainly a function of the MP3 encoder and the bitrate that a given song has been encoded at. An interesting article which compares the popular encoders can be found here. There is also an MP3 analyser that can estimate the quality of MP3 recordings, and is downloadable from here.

Also be sure to connect your power supply in a 'star' configuration to prevent noise coupling from the HDD electronics into the MP3 player audio stage. That is, have dedicated power leads for the HDD 5V and the player 5V. If you have a noisy HDD, the use of an electrolytic or local 7805 voltage regulator at the MP3 player power connector should clean this up.

How can I attach a keypad?

The easiest way of doing this is to adapt an IR remote. Alternatively, I have constructed a simple keypad project kit using a PIC12C508A, an IR LED, and five buttons.

What is required to get a working unit?

The basic kit consists of a fully populated and tested MP3 player PCB. Also included is a flying 5VDC power-lead, with a mating plug. The LCD option consists of a green LED-backlit LCD module, with a 20-way mating plug soldered onto it. There are also four spacers and screws provided to fix the LCD onto the PCB.

To get an operational MP3 player, you will need to add an IDE (PC) HDD, a 40-way IDE cable, a DC power supply, and a suitable IR remote.

Almost any IDE HDD will do, however, try to avoid the older Western Digital drives (< 2GB) as these tend to use CHS instead of LBA mode addressing. Anything above 2GB will work, as these drives always use LBA.

The most suitable IR remotes to use are old VCR and CD player ones. The MP3 player recognises the 'Japanese' and 'Common' IR encoding methods. See the manual for further details. There is also a universal remote option.

Does the decoder support variable bit rates recordings (VBRs)?

Yes, these work fine. The LCD display will display the average bitrate of the encoded stream. This is updated every second.

What is the expected delivery time to my country?

This varies depending on how busy the postal and customs services are, but is typically around 7-14 days.

Why is the playback order different from that shown in windows explorer?

Windows automatically sorts the contents of a directory, so the actual storage order usually varies from that shown on the screen. The following tool will sort physical directory contents (Many thanks to Manning for the link).

Where can I find a suitable enclosure?

A good physical layout is to find an enclosure which will house your HDD and its power supply, and then put the player PCB & display behind a front panel, cutting a hole (if necessary) for the LCD. A few people have adapted HDD caddies ,which include a HDD power supply and a USB-IDE interface. These gadgets are available at most local computer shops. (Many thanks to Manning & Harvey).

Where can I find more information?

There is an acrobat PDF format installation & operation manual downloadable from here.

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