Nintendo 1504166 - Game Boy Advance SP Edition Console Programming Manual page 152

AGB Programming Manual
JOYSTAT [d03] Send Status Flag
When an AGB write data signal is received, this is set. If a word read is
done with the JOY_RECV Register it is reset.
JOYSTAT [d01] Receive Status Flag
When a word write is done with the JOY_TRANS Register, this is set. If an
AGB read data signal is received it is reset.
JOY Bus Communication Operations
AGB JOY Bus communication recognizes four commands sent from the
host (DOL, etc.): [Device Reset], [Type/Status Data Request], [AGB Data
Write], and [AGB Data Read]. AGB operates based on the particular signal
received.
The transfer of the bit data for JOY Bus communication is done in units of
bytes and in the order of MSB first.
§
[Device Reset] Command(FFh) Received
The device reset signal receive flag for Register JOYCNT is set.
If the interrupt request enable flag for the same register is also set, a JOY
Bus interrupt request is generated.
Direction Order
Receive 1
1
2
Send
3
§
[Type/Status Data Request] Command(00h) Received
Returns 2 byte type number(0004h) and 1 byte communication status.
Direction Order
Receive 1
1
2
Send
3
©1999 - 2001 Nintendo of America Inc.
d7 d6 d5 d4
1 1 1 1
0 0 0 0
0 0 0 0
Lower 8 bits of Register JOYSTAT
d7 d6 d5 d4
0 0 0 0
0 0 0 0
0 0 0 0
Lower 8 bits of Register JOYSTAT
152
d3 d2 d1 d0
1 1 1 1
0 0 0 0
0 1 0 0
d3 d2 d1 d0
0 0 0 0
0 0 0 0
0 1 0 0
Communication Functions
Remarks
Command 255(FFh)
Type Number
0400h
Communication Status
Remarks
Command 0(00h)
Type Number
0400h
Communication Status
D.C.N. AGB-06-0001-002B4