NXP Semiconductors PN544 C2 - CRC Description; Example

NXP Semiconductors
UM191812
PN544 C2 User Manual
191812 All information provided in this document is subject to legal disclaimers. © NXP B.V. 2010. All rights reserved.
User Manual Rev. 1.2 — 2010-06-16 23 of 172
Example of change baud rate LLC frame
(5) Change baud rate to 9600 (00h)
Fig 14. example of change baud rate LLC frame
7.4.4 CRC description
The detection of errors in a frame is based on the standard CRC-16 defined in [2]. The
CRC polynomial is:
X
16
+X
12
+ X
5
+1.
Its initial value is 0xFFFF.
The CRC is computed on the bits between SOF and EOF both excluded. So in order to
detect invalid frames the CRC shall be taken as a primary measure to check validity. The
maximum size of a single frame is (LEN+HDR+PAYLOAD_MAX+CRC = 1 + 1 + 29 + 2)
33 Bytes.
7.4.4.1 Example
The CRC of a
n RSET and an UA is as follows:
C3F9 04 00 E505
CRC
Endpoint
Cap.
Window
size
RSETLength
17E6 A703
CRCUALength
Fig 15. CRC examples