ACS ACR122L User Manual page 10

C. Activate a SAM (Incorrect Checksum, RDR).
1. HOST sends a frame.
2. RDR sends back a
positive status frame
immediately.
3. RDR sends back the
response (corrupted) of
the command.
4. HOST sends a NAK
frame to get the
response again.
5. RDR sends back the
response of the
command.
Note: If the frame sent by the HOST is correctly received by the RDR, a positive status frame = {02
00 00 03} will be sent to the HOST immediately to inform the HOST the frame is correctly received.
The HOST has to wait for the response of the command. The RDR will not receive any more frames
while the command is being processed.
In case of errors, a negative status frame will be sent to the HOST to indicate the frame is either
corrupted or incorrectly formatted.
CheckSum Error Frame = {02 FF FF 03}
Length Error Frame = {02 FE FE 03}. The length "dDwLength" is greater than 0105h bytes.
ETX Error Frame = {02 FD FD 03}. The last byte is not equal to ETX "03h".
TimeOut Error Frame = {02 FC FC 03}. Not Complete Package Received.
The NAK Frame is only used by the HOST to get the last response.
{02 00 00 00 00 00 00 00 00 00 00 00 03} // 11 zeros
ACR122L – Communication Protocol
Version 1.03
HOST
02 62 00 00 00 00 00 01 01 00 00 [Checksum] 03

02 00 00 03 (positive status frame)
.. After some processing delay...
02 80 0D 00 00 00 00 01 00 00 00 3B 2A 00 80 65

24 B0 00 02 00 82 90 00 [Incorrect Checksum] 03
02 00 00 00 00 00 00 00 00 00 00 00 03 (NAK)
02 80 0D 00 00 00 00 01 00 00 00 3B 2A 00 80 65
24 B0 00 02 00 82 90 00 [Checksum] 03
RDR
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