Specifications

Receive MP3

data from

server

Increment the

receive

pointer

Reset the

poin ter if it is

past the buffer

boundary

Is the

buffer set

to refill

Is it full

Start the

decoder

Calculate the

buffer size

If buffer is empty

send indiactor to

HyperTerminal

Is the

buffer

full

Send indicator to

HyperTerminal

and wait for there

to be room in the

buffer for another

receive.

Yes

Figure 18 First program to play MP3 data

The program starts by receiving the data into the buffer. When the buffer gets to a size

of greater than 10Kbytes the global variable enabling transmission of data to the

encoder is enabled and the software trigger is called to start the first interrupt. The

interrupt needs to be software triggered whenever the decoder is currently not

transferring and the program wants to start a transfer. The decoder is not transferring

(not making data requests) in the first instance of use with the decoder or when the

decoder has requested data but the MP3 data buffer is empty or transmission to the

decoder has been disabled. To trigger the interrupt with software a signal can be sent to