自制MP3播放器

文章摘要： USBThe USB link is controlled by a FT8U245BM chip from FTDI. This is a VERY easy to use USB chip, which basically looks like a simple 8-bit buffer (hence the name). There's no need for implementing any specific USB code in the player, to communicate over the USB link, you just read and write d

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USB

The USB link is controlled by a FT8U245BM chip from FTDI. This is a VERY easy to use USB chip, which basically looks like a simple 8-bit buffer (hence the name). There's no need for implementing any specific USB code in the player, to communicate over the USB link, you just read and write data directly to the chip.

Two status pins indicate if there's any data in the receive buffer, and if the transmitter queue is empty.

The USB chip is memorymapped and occupies a single address in the CPU address space.

Some discrete circuitry is added to the USB chip to enable it to startup in the correct mode, and to handle the power on reset and Soft-Connect feature.

 

 

Li-Ion charger

A Maxim MAX1811 chip is added for handling the charging of the Li-Ion cell.(Ni-Mh cells can also be used in the player, in this case, the MAX1811 is replaced by a diode and a resistor).

The MAX chip is a special USB to Li-Ion charger, and it controls the relatively complicated charge sequence to the Li-Ion cell.

The Li-Ion cell (or Ni-Mh cells), supply 3.6V to the other components.

 

 

Memory card Interface

The player can be used with either a Compact Flash card or a MultiMedia Card.

The Compact Flash (CF) interface is pretty similar to a standard ATA interface. The nice thing about it, is that it can run in 8-bit mode, making it very simple to interface to a microprocessor.

In the yampp-7, the CF interface is mapped directly into the memorymap of the processor. To control the CF card and to read/write data, the standard ATA register bank of is used, and address bits A8-A11 is used to select the register.

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