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STAMP-D5 build-in my car:Actually the MP3-player is connected via an adapter-cassette with the car-radio. The source-input channel of the car-radio is not so easy to use (see text below). Additionally, I set up a 12V to 5V DC/DC-converter to get the player run in the car. |
| Open box with LC-display, cabling and pcb for buttons and buttonwheel. Between my pcb and the display you can see some kind of adapter-ic. This is a tri-state-buffer (74hc245) to disconnect the display-bus from the databus. It can't operate in tri-state-mode. |
Here you can see the IDE-harddisk - mounted "on the fly". The IDE is only laying on foam rubber and clamped in that bumpers. Nevertheless, the padding isn't necessary. Now I have screwed the harddisk directly to a plastic plate and use the player now over 1000 of kilometers without any "headcrashes". |
Priority List "Next ToDo"
Please have a look to the paragraph of the plans page
User Guide - Keypad and Wheelfunction
These are the most actions and reactions you can use with the 3-button keypad and the wheel.
There are more functions available when the player is controlled by a terminal application over the PC, but these are more for debugging purpose and to check some new inventions.
States
+/-
<SPACE>The primary feature while playing is:
if a song has finished playing, the next song will be choosen. If this was the last song in album, the upper directory will be loaded and displayed and the cursor moves to the next album-entry. This could be once more the last in the directory, so the cursor stands in front of a ".."-Entry.These are the print-outs over the serial interface:
If the IR-remote-control is implemented, you can find here the description of the protocol and the conversion for the MMI.
Performance and Testresults
- Now I used the player over more than 3000 km in the car, most times over some hours at one time and more or less over 100 hours at home. The harddisk works shockresistant in the car - but don't leave the streets with your car!
- Powerconsumption:
Measured at 12V.00 V (Agilent E3642A) and DC/DC-converter LM2575-5 (car-version, with LCD-backlight on):
- playing constant: 234 mA
- not playing (idle): 140 mA
- hd-sleep-mode: 107 mA => 2.8W / 1.68W / 1.28W power consumption at all.
- Actually I use a 30GB laptop harddisk (Fujitsu MHT2030-AT) with 9GB of mp3-files. The old version worked with a 5 GB IBM-model which is reduced via firmware to 3 GB.
- The directory structure works with max. 3 levels:
The 1st level identifies the band or author name
The 2nd level identifies the album, while the filename identifies the songname. But also all MP3-ID-Headerinformation will be used (only ID-version 2.3, because these are laying at top of the files).
- Most MP3-files have a fixed bitrate of 128KB/sec. But I also have songs with 160KB/s and some with variable bitrates up to 192KB/s.
- One time I reduced the processor-performance by increasing the memory-waitstates by 5 times - the player was working in a correct way. I think that this good behaviour is based on the PEC-transfers, which do the most datatransfers and for which the cpu does not need to fetch and decode an opcode!
- The software has reached 31 KBytes of binary code. So it uses only 5% of the whole Flash-ROM.
The code uses only 6KB of the external SRAM (128KB). All other stuff lies in the fast internal 3KB SRAM. (the 6KB depend on the max. number of allowed directories. Actually it uses 61 of 64 possible).
Findings
- At the moment it was not possible to explore the CD-changer protocol of the "Blaupunkt" car-radio. Because the radio is directly connected to the security-system of the car (via CAN-bus) and does not work outside of the car.
May be I can use a laptop to write and debug the protocol in my car...
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own risk.
For problems or questions regarding this web contact Christoph.
Last updated: 22/08/04.
