Audio player according to the “tape” concept

System (module) presented here is an atypical audio player. It is similar to a cassette player. Despite the fact that the sound is saved as files on CF card, the microprocessor does not treat data as a file system, but as a continuous area. The system was created as an executive model for an alarm clock and independent player in the places where you are from time to time and have a fancy for music (e.g. bathroom, workshop, etc.). Undeniable advantage is starting in a split second.
There are following buttons on the schema:

• KPLAY – alternately enables and disables the playback
• KRAND – random jumps across the card
• KREW – simulates backward with interception
• KFF – simulates forward with interception

Besides, there are two configuration inputs:
SSTOP – shorted makes that after powering the system will not play but wait for pressing KPLAY, unplugged – after powering the system begins playing immediately, SNRAND – shorted makes that every time you press KPLAY will not cause a random jump, but continue playing from last position, unplugged – each time you press KPLAY, it will jump in a random place.
The system controls LEDs in two groups:

• simple (LEDs PLAY and STOP) – corresponding LED lights up according to the state. When scrolling, LED PLAY flashes, by pushing KRAND both LEDs are lit
• showy (LEDs connected to outputs 10-13) – allows the execution of the characteristic, unobtrusive light animation in the form of intersecting lights

Both the systems may be used independently. If you do not need them, you will not have to mount 4 capacitors 1mF, 8 resistors 1kR and 2 resistors 2,2kR.



Data format
The system accepts raw audio format (RAW), Mono 22,050kHz frequency for the microprocessor 89S51(2) and 44,1kHz for microprocessor 89S8253. Frequency of play obviously depends on the frequency of the quartz.
Depending on the specific D/A transducer, load the appropriate software as well as prepare audio files. And so:

• TDA1543 requires cf_player_1543.hex charge and files of byte order MBS/LBS in audio files
• TDA1311A requires cf_player_1543a_1311a.hex charge and files of byte order MBS/LBS in audio files
• TDA1543A requires cf_player_1543a_1311a.hex charge and files of byte order LBS/MBS, which is identical as in WAV format. This means that in this case, the system also plays mono WAV files without conversion, but at the start of play we can hear a short *****

To convert files, one of popular audio editing programs like Audacity, CoolEdit etc. can be used. They contain operation modules with multiple files, which greatly simplifies the work.

CF card
The system was designed to work only with card with capacity of 8GB. Because of the simplify, the system reads only LBA area of the card, whose third byte is in the range 1...237. It means that data area from 32MB to 7584MB (rounded) is read. Files outside this range will not be played. Since the system was designed as the executive part of alarm clocks or audio players, it is not clear limited. At 22,05kHz it allows to record approximately 50 hours of music. Just remember that after removal of the entire files, record all again after formatting the card and if you do not fill all with files, you should make a copy of existing files to fill the card (so with a random jump, you do not enter the area without data).

Additional comments
CF connector is very difficult to solder because of the narrow gauge of pins. Pins on the board are not consistent with the size of the serial, but expanded. Unused pins should be removed, and the other moved as in the picture. Remember only to tighten the connector with screws M2,5 before soldering.



Capacitor connected to the 3,2 output of the microprocessor decides the random jump after enabling the power. When SNRAND or SSTOP output shorted, it would not be needed.
Amplifier (TBA820) is needed only when the speaker will be directly controlled. It does not have to be mounted when we have a separate system with an amplifier.



There is a space for a rectifier, stabilizer and associating systems on the board. They can be omitted when we have a 5V stabilized power supply.
Resistor on leg L of the transmitter sets the voltage at the leg. It should contain between 2-3V. Please note that some of the resistance is also a volume control.
Any speaker can be attached to the system, and the power will not exceed few hundred milliwatts. Current consumed by the whole is about 100mA plus the power needed to control the speaker.

Link to original thread (attachment) – Odtwarzacz plików audio według koncepcji ''taśmowej''