Nintendo 1504166 - Game Boy Advance SP Edition Console Programming Manual page 139

AGB Programming Manual
2)Slave(d00 is 0)
Set during input of transmit start bit (LO source oscillation cycle × 3
(approx. 180ns)), and reset when transfer is complete.
SIOCNT [d06] Communication Error Flag
The communication status can be confirmed at the end of a
communication. (During communication, it is not reflected properly.)
If the status for this bit is 0, there is no error. If it is 1, it means an error has
occurred.
This error flag is automatically set in the following situations:
- The SI Terminal does not become LO during the interval when the
"SYNC signal" is being input(the master is outputting).
Example: When connected to the fifth slave or after that, or when the
previous slave is not connected.
- The stop bit for the receive data is not HI(Framing Error)
However, communication continues even when an error occurs, and
invalid data is stored in SIOMULTI0-SIOMULTI3.
Confirm error flags when communicating so there are no problems
created in case of an incorrect cable connection.
SIOCNT [d05 - 04] Multi-player ID Flag
When multi-player communication ends, an ID code will be stored which
specifies the order that each particular machine was connected.
Confirm ID code when communicating so there are no problems created in
case of an incorrect cable connection.
SIOCNT [d03] SD Terminal
The status of the SD Terminal can be read. If all of the connected
terminals enter multi-player communication mode, it becomes HI status.
SIOCNT [d02] SI Terminal
The status of the SI Terminal can be read.
When all of the connected terminals are in multi-player communication
mode, this shows that the terminal which is LO input to the SI terminal is
the master. HI input means that it is a slave.
Prior to communication starting, it is not possible to determine the number
order of a particular slave.
©1999 - 2001 Nintendo of America Inc.
139
Communication Functions
D.C.N. AGB-06-0001-002B4