WIP

NIIMBOT printers protocol

Packet structure

Main packet

Prefix - prefix 0x03 is present in only one command - Connect.
Head - always 2 bytes (0x55 0x55).
Command - command (packet) identifier.
Data Length - number of bytes of data.
Data - data with Data length length.
Checksum - calculated by XOR of all bytes from Command to the last byte of Data (inclusive).
Tail - always 2 bytes (0xAA 0xAA).

CRC32 (firmware) packet

Head - always 2 bytes (0x55 0x55).
Command - command (packet) identifier.
Index - firmware chunk index, used only in FirmwareChunk and In_RequestFirmwareChunk packets, otherwise equals zero.
Data Length - number of bytes of data.
Data - data with Data length length.
Checksum - crc32 checksum of all bytes from Command to the last byte of Data (inclusive).
Tail - always 2 bytes (0xAA 0xAA).

List of packets

Request ID	Name	Response ID(s)	Simple	CRC32
0x01	PrintStart	0x02	✅
0x03	PageStart	0x04	✅
0x05	PrinterLog	0x06	✅
0x0b	AntiFake	0x0c	✅
0x13	SetPageSize	0x14
0x15	PrintQuantity	0x16
0x1a	RfidInfo	0x1b	✅
0x1c	RfidInfo2	0x1d	✅
0x20	PrintClear	0x30	✅
0x21	SetDensity	0x31
0x23	SetLabelType	0x33
0x27	SetAutoShutdownTime	0x37
0x28	PrinterReset	0x38	✅
0x40	PrinterInfo	0x4f, 0x47, 0x4d, 0x4a, 0x41, 0x4c, 0x43, 0x46, 0x48, 0x4b, 0x49, 0x42
0x54	RfidSuccessTimes	0x64	✅
0x58	SoundSettings	0x68
0x59	CalibrateHeight	0x69
0x5a	PrintTestPage	0x6a	✅
0x70	WriteRFID	0x71
0x83	PrintBitmapRowIndexed	⚠ one way
0x84	PrintEmptyRow	⚠ one way
0x85	PrintBitmapRow	⚠ one way
0x8e	LabelPositioningCalibration	0x8f	✅
0x91	FirmwareCrc	⚠ one way		✅
0x92	FirmwareCommit	⚠ one way		✅
0x9b	FirmwareChunk	⚠ one way		✅
0x9c	FirmwareNoMoreChunks	⚠ one way		✅
0xa3	PrintStatus	0xb3	✅
0xa5	PrinterStatusData	0xb5	✅
0xaf	PrinterConfig	0xbf
0xc1	Connect	0xc2	✅
0xda	CancelPrint	0xd0	✅
0xdc	Heartbeat	0xde, 0xdf, 0xdd, 0xd9
0xe3	PageEnd	0xe4	✅
0xf3	PrintEnd	0xf4	✅
0xf5	StartFirmwareUpgrade	0xf6

Comes from printer only:

Request ID	Name	Client response ID	CRC32
0xe0	In_PrinterPageIndex
0x90	In_RequestFirmwareCrc	0x91	✅
0x9a	In_RequestFirmwareChunk	0x9b	✅
0x9d	In_FirmwareCheckResult		✅
0x9e	In_FirmwareResult		✅

Packet details

Simple packet

This packet has Request ID, Data length=1, and Data=1.

Checksum will be same as Request ID because N^1^1 == N.

Example (RfidInfo):

55 55 1a 01 01 1a aa aa
       │  │  │  │
       │  │  │  └─ Checksum (1a^01^01)
       │  │  └─ Data
       │  └─ Data length
       └─ RfidInfo command

Packet details (image data packets)

See print tasks to understand how to images are printed.

PrintEmptyRow

Used to fill row with blank (white) pixels.

Example:

55 55 84 03 00 04 02 81 aa aa
       │  │  └──┤  │  │
       │  │     │  │  └─ Checksum
       │  │     │  └─ Repeat count (repeat row two times)
       │  │     └─ Row number is 4
       │  └─ Data length
       └─ PrintEmptyRow command

PrintBitmapRowIndexed

Used when black pixel count is less than 7. Data is encoded with pixel indexes (unsigned 16-bit integers).

Information about Black pixel count segment can be found in API.Utils.countPixelsForBitmapPacket function docs.

Usually printer prints without problems when all of 3 bytes are zeros.

Example:

55 55 83 0a 00 03 02 00 00 02 00 0a 01 40 c1 aa aa
       │  │  └──┤  └──┴──┤  │  └──┤  └──┤  │
       │  │     │        │  │     │     │  └─ Checksum
       │  │     │        │  │     │     └─ Draw pixel at x=320
       │  │     │        │  │     └─ Draw pixel at x=10
       │  │     │        │  └─ Repeat count (repeat row two times)
       │  │     │        └─ Black pixel count (see above)
       │  │     └─ Row number is 3
       │  └─ Data length
       └─ PrintBitmapRowIndexed command

PrintBitmapRow

Used to send full row segment that includes both black and white pixels.

Image row example:

pixels

Packet example:

55 55 85 0a 00 00 13 00 00 01 ff 00 df 0f b2 aa aa
       │  │  └──┤  └──┴──┤  │  └──┴──┴──┤  │
       │  │     │        │  │           │  └─ Checksum
       │  │     │        │  │           │
       │  │     │        │  │           └─ Draw 32 pixels (19 black, 13 empty)
       │  │     │        │  └─ Repeat count (repeat row 1 time)
       │  │     │        └─ Black pixel count (19)
       │  │     └─ Row number is 0
       │  └─ Data length
       └─ PrintBitmapRow command

Other packets example

55 55 40 01 0b 4a aa aa - get device serial number
55 55 1a 01 01 1a aa aa - get rfid data
55 55 58 03 01 01 01 5a aa aa - enable Bluetooth connection sound
55 55 58 03 01 01 00 5b aa aa - disable Bluetooth connection sound