Waveshare UART Fingerprint Sensor, User Manual

Page: 9 / 18

UART Fingerprint Sensor (C)
V1.0 www.waveshare.com 9 / 18
Byte 1 2 3 4 5 6 7 8
CMD 0xF5 0x0A
User
ID(High
8Bit )
User
ID(Low8Bit )
0 0 CHK 0xF5
ACK 0xF5 0x0A 0 0
Permission
(1/2/3)
ACK_NOUSER
0 CHK 0xF5
13. Set/Query comparison level
（
CMD/ACK both 8 Byte
）
Byte 1 2 3 4 5 6 7 8
CMD 0xF5 0x28 0
Byte5=0: New Level
Byte5=1: 0
0
：
Set Level
1
：
Query Level
0 CHK 0xF5
ACK 0xF5 0x28 0 Current Level
ACK_SUCCUSS
ACK_FAIL
0 CHK 0xF5
Notes
：
Comparison level can be 0~9, larger the value, stricter the comparison. Default 5
14. Acquire image and upload
（
CMD=8 Byte/ACK >8 Byte
）
CMD Format
：
Byte 1 2 3 4 5 6 7 8
CMD 0xF5 0x24 0 0 0 0 CHK 0xF5
ACK Format
：
1
）
Data head
：
Byte 1 2 3 4 5 6 7 8
ACK 0xF5 0x24 Hi(Len) Low(Len)
ACK_SUCCUSS
ACK_FAIL
ACK_TIMEOUT
0 CHK 0xF5
2
）
Data packet
Byte 1 2---Len+1 Len+2 Len+3
ACK 0xF5 Image data CHK 0xF5
Notes
：
In DSP module, the pixels of fingerprint image are 280*280, every pixel is represented by 8
bits. When uploading, DSP is skip pixels sampling in horizontal/vertical direction to reduce data
size, so that the image became 140*140, and just take the high 4 bits of pixel. each two pixels
composited into one byte for transferring (previous pixel high 4-bit, last pixel low 4-pixe).
Transmission starts line by line from the first line, each line starts from the first pixel, totally
transfer 140* 140/ 2 bytes of data.
Data length of image is fixed of 9800 bytes.
15. Acquire image and upload eigenvalues
（
CMD=8 Byte/ACK > 8Byte
）
CMD Format
：
Byte 1 2 3 4 5 6 7 8
CMD 0xF5 0x23 0 0 0 0 CHK 0xF5
ACK Format
：
1
）
Data head
：