Registers

Old3DS	Name	Address	Width
Yes	PXI_SYNC9	0x10008000	4
Yes	PXI_CNT9	0x10008004	4
Yes	PXI_RECV_FIFO9	0x10008008	4
Yes	PXI_SYNC11	0x10163000	4
Yes	PXI_CNT11	0x10163004	4
Yes	PXI_SEND11	0x10163008	4
Yes	PXI_RECV_11	0x1016300C	4

The PXI registers are similar to those on DS.

PXI_CNT

Bit	RW	Description
0	R	Send Fifo Empty Status (0=Not Empty, 1=Empty)
1	R	Send Fifo Full Status (0=Not Full, 1=Full)
2	R/W	Send Fifo Empty IRQ (0=Disable, 1=Enable)
3	W	Send Fifo Clear (0=Nothing, 1=Flush Send Fifo)
8	R	Receive Fifo Empty (0=Not Empty, 1=Empty)
9	R	Receive Fifo Full (0=Not Full, 1=Full)
10	R/W	Receive Fifo Not Empty IRQ (0=Disable, 1=Enable)
14	R/W	Error, Read Empty/Send Full (0=No Error, 1=Error/Acknowledge)
15	R/W	Enable Send/Receive Fifo (0=Disable, 1=Enable)