NXP Semiconductors
UM191812
PN544 C2 User Manual
191812
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User Manual
Rev. 1.2 — 2010-06-16
14 of 172
7.4 LLC on I
2
C, SPI, UART
The link layer of the host protocol is derived from the ETSI SWP specification. The
deviations from the ETSI LLC layer are as follows:
•
CLT protocol is not supported
•
ACT protocol and SYNC_ID handling are not supported
HSU baudrate can be either configured by EEPROM or by an additional argument in
RSET from the host interface
•
The host is supposed to start with the activation of the link layer
Note: This means that the host will start with the RSET frame.
The optional features / parameters are as follows:
Window size is 4, can be negotiated down to 2.
SREJ is not supported
Retry rate is set to 10
Inter-frame character timeout (See 7.4.5)
WARNING:
A minimum delay of
1.1ms
between to consecutive frames sent to
PN544 is required. Thus, Host Link driver must ensure to respect this timing when
sending U-Frame, I-Frame & S-Frame.
7.4.1 Frame definition
The frame format is the same for all host interfaces. It is derived from the LLC frame as
specified in the SWP specification. The major difference between host and SWP frame is
that the host interface frames contain the length information. Otherwise, things like the
LLC command set (I, RR, RNR, REJ, RSET), frame length and LLC handshaking is
identical. Bit stuffing is not used by the host interfaces.
HCI Command / Event / Response
LLC
Header
max 29 Bytes
1 Byte
CRC
LLC
Length
2 Bytes
1 Byte
LLC payload
Fig 4. LLC Frame Components