Freescale Semiconductor Symphony DSP56724 Reference Manual page 256

EMC Burst Buffer
17.3.3.2 Burst Write
There are two burst write buffers; one burst write buffer for Shared Bus master 0, and one burst write
buffer for Shared Bus master 1. Each Shared Bus master use its own write buffer independently.
Each write buffer has 16 24-bit words alternating (ping-pong style operation) between the two sets of eight
words, and there are two 8-word buffers in each write buffer.
The burst write length can be 1 to 8 words. In one write buffer, each 8-word buffer has a 26-bit base address
register the same as the read buffer.
When a burst write access occurs, the EMC Burst Buffer checks the current 8-word buffer being used.
• If the 8-word buffer is empty, or the access address is a sequential address following the last burst
write access and the buffer is not full, then the 8-word buffer stores the write data in it, terminates
the access immediately without involving the EMC, and returns the address of the first write data
is stored into the base address register.
• If the 8-word buffer is not empty and is not a sequential address, the sub-buffer stores the write data
left in it into external memory through the EMC, by executing a burst operation (the burst length
is the number of data words in the buffer). At the same time, the module sets the other 8-word
buffer as the current buffer to accept the following write data, and the write access address is
recorded in the corresponding base address register.
When a 8-word buffer is storing write data into external memory, the other 8-word buffer can continue to
accept write data from the Shared Bus, unless the 8-word buffer is not empty, or if the write access address
is not sequential with the last write access address, or if the 8-word buffer is full. If the other 8-word buffer
needs to execute a burst operation to flush itself, it must wait until after the other 8-word buffer's burst
operation has finished.
Symphony DSP56724/DSP56725 Multi-Core Audio Processors, Rev. 0
17-8 Freescale Semiconductor