RegistersEdit

Old3DS Name Address Width Used by
Yes HID_PAD 0x10146000 2 Boot9, Boot11, Kernel11, TwlBg, HID Services, dlp Services
Yes HID_PAD_CNT 0x10146002 2 TwlBg

HID_PADEdit

Each bit in this register refers to a particular key. Each bit is set if the corresponding key is not pressed, and unset if it's pressed.

Bit Key
0 A
1 B
2 Select
3 Start
4 Right
5 Left
6 Up
7 Down
8 R
9 L
10 X
11 Y

HID_PAD_CNTEdit

Bit Key
0 A
1 B
2 Select
3 Start
4 Right
5 Left
6 Up
7 Down
8 R
9 L
10 X
11 Y
12-13 Unused.
14 Enable IRQ 0x5B. 1 = enable.
15 IRQ condition (0 = OR, 1 = AND).

This is the same as on GBA/DS(i).