CLRC663 Datasheet, PDF (25/132 Pages) NXP Semiconductors – Contactless reader IC

NXP Semiconductors
CLRC663
Contactless reader IC
SDA
SCL
data line stable;
data valid
Fig 17. Bit transfer on the I²C-bus.
change
of data
allowed
001aam300
8.4.4.3 I²C START and STOP conditions
To handle the data transfer on the I²C-bus, unique START (S) and STOP (P) conditions
are defined.
A START condition is defined with a HIGH-to-LOW transition on the SDA line while SCL is
HIGH.
A STOP condition is defined with a LOW-to-HIGH transition on the SDA line while SCL is
HIGH.
The master always generates the START and STOP conditions. The bus is considered to
be busy after the START condition. The bus is considered to be free again a certain time
after the STOP condition.
The bus stays busy if a repeated START (Sr) is generated instead of a STOP condition. In
this respect, the START (S) and repeated START (Sr) conditions are functionally identical.
Therefore, the S symbol will be used as a generic term to represent both the START and
repeated START (Sr) conditions.
SDA
SDA
SCL
S
START condition
Fig 18. START and STOP conditions
SCL
P
STOP condition
001aam301
8.4.4.4 I²C byte format
Each byte has to be followed by an acknowledge bit. Data is transferred with the MSB
first, see Figure 18 “START and STOP conditions”. The number of transmitted bytes
during one data transfer is unrestricted but shall fulfil the read/write cycle format.
CLRC663
Product data sheet
COMPANY PUBLIC
All information provided in this document is subject to legal disclaimers.
Rev. 3.3 — 3 April 2012
171133
© NXP B.V. 2012. All rights reserved.
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