IR Service "ir:u"

Command Header Description
0x00010000 Initialize
0x00020000 Shutdown
0x00030042 StartSendTransfer
0x00040000 WaitSendTransfer
0x000500C2 StartRecvTransfer
0x00060000 WaitRecvTransfer
0x00070000 GetRecvTransferCount
0x00080000 GetSendState
0x00090040 SetBitRate
0x000A0000 GetBitRate
0x000B0040 SetIRLEDState
0x000C0000 GetIRLEDRecvState
0x000D0000 GetSendFinishedEvent
0x000E0000 GetRecvFinishedEvent
0x000F0000 GetTransferState
0x00100000 GetErrorStatus
0x00110040 SetSleepModeActive
0x00120040 SetSleepModeState

IR Service "ir:USER"

Command Header Available since system version Description
0x00010182 InitializeIrnop
0x00020000 FinalizeIrnop
0x00030000 ClearReceiveBuffer
0x00040000 ClearSendBuffer
0x00050000 WaitConnection
0x00060000 RequireConnection
0x00070000 AutoConnection
0x00080000 AnyConnection
0x00090000 Disconnect
0x000A0000 GetReceiveEvent
0x000B0000 GetSendEvent
0x000C0000 GetConnectionStatusEvent
0x000D0000 SendIrnop
0x000E0000 SendIrnopLarge
0x000F0000 ReceiveIrnop
0x00100000 ReceiveIrnopLarge
0x00110000 GetLatestReceiveErrorResult
0x00120000 GetLatestSendErrorResult
0x00130000 GetConnectionStatus
0x00140000 GetTryingToConnectStatus
0x00150000 GetReceiveSizeFreeAndUsed
0x00160000 GetSendSizeFreeAndUsed
0x00170000 Unknown, >2.0.0-2 GetConnectionRole
0x00180182 Unknown, >2.0.0-2 InitializeIrnopShared
0x00190040 Unknown, >2.0.0-2 ReleaseReceivedData
0x001A0000 Unknown, >2.0.0-2 SetOwnMachineId

IR Service "ir:rst"

Command Header Available since system-version Description
0x00010000 8.0.0-18 GetHandles
0x00020080 8.0.0-18 Initialize
0x00030000 8.0.0-18 Shutdown
0x00040000 8.0.0-18 This writes an unknown u8 to index-word cmdreply[2], from data loaded from an I2C device register.
0x00050000 8.0.0-18 This writes an unknown u8 from IR-module state to index-word cmdreply[2].
0x00060000 8.0.0-18 This writes two unknown u8 fields from IR-module state to index-word cmdreply[2] and cmdreply[3].
0x00070080 9.0.0-20 (u8 unk0, u8 unk1) ?
0x00080000 9.0.0-20 (u8 unk0, u8 unk1) ?
0x00090000 9.0.0-20 This writes two unknown u8 fields to index-word cmdreply[2] and cmdreply[3].

This service was added with 8.0.0-18. Unlike the other IR services, this uses I2C deviceid 17(this deviceid isn't actually handled by the 8.0.0-18 I2C module). This is for the additional New 3DS HID hardware, this HID data is stored in shared-memory. Even with 9.0.0-20 IR module still registers+handles this service on both Old3DS+New3DS.

IR Services

Only one session(two sessions starting with 8.0.0-18) to any of these services can be open at a time, thus only one/two process(es) can use any of these services at once. These services interface with hardware services gpio::IR and i2c::IR. The i2c::IR service is used for sending/receiving data.

IRU is for regular IR comms. IRUSER uses a custom IR protocol(above the physical layer). Both of these services use IrDA-SIR. The IR hardware seems to only support IrDA-SIR, other physical protocols such as the one for TV-remotes are not supported(going by the datasheet linked here for a different IC at least).

The protocol used with IRUSER involves encryption(?) implemented in software. IRUSER is used for the Circle Pad Pro. This same IRUSER service uses the New3DS HID hardware when running on New3DS(note that the main service for New3DS HID is ir:rst).