- Linux MultiMedia Studio Computer Accessories User Manual

Appendix 1: DPR Map
MN1278 05.2001
63
6.8 Pseudo Serial Interface
The serial interface works by implementing a 64 word circular buffer within DPR. There is one such buffer for
the receive buffer and one for the transmit buffer. Head and tail pointers are also located in DPR allowing both
sides of DPR to check the status of the buffers.
The serial interface occupies DPR locations 0x150 to 0x1D5 in the following configuration:
Txd Buffer
0x85
0x46
Txd Reserved 0x45
Txd Tail 0x44
Txd Head 0x43
Rxd Buffer
0x42
0x03
Rxd Reserved 0x02
Rxd Tail 0x01
Rxd Head 0x00
The buffer itself has two sets of symbolic constants, depending on which side, NextMove or host, that is using
them.
Offset Symbolic Constant - Host Symbolic Constant - NextMove
0x00
ofTXD_HEAD ofNM_RXD_HEAD
0x01
ofTXD_TAIL ofNM_RXD_TAIL
0x03
ofTXD_BUFFER ofNM_RXD_BUFFER
0x43
ofRXD_HEAD ofNM_TXD_HEAD
0x44
ofRXD_TAIL ofNM_TXD_TAIL
0x46
ofRXD_BUFFER ofNM_TXD_BUFFER
The offsets from the start of the serial interface are shown in hex. The start of the serial I/O buffer has a symbolic
constant of
ofSERIAL_IO_BASE
.