Product data

MFRC631 All information provided in this document is subject to legal disclaimers. © NXP B.V. 2014. All rights reserved.
Product data sheet
COMPANY PUBLIC
Rev. 3.3 — 4 February 2014
227433 19 of 120
NXP Semiconductors
MFRC631
High performance ISO/IEC 14443 A/B reader solution
8.4.4 I
2
C-bus interface
8.4.4.1 General
An Inter IC (I
2
C) bus interface is supported to enable a low cost, low pin count serial bus
interface to the host. The implemented I
2
C interface is mainly implemented according the
NXP Semiconductors I
2
C interface specification, rev. 3.0, June 2007. The MFRC631 can
act as a slave receiver or slave transmitter in standard mode, fast mode and fast mode
plus.
The following features defined by the NXP Semiconductors I
2
C interface specification,
rev. 3.0, June 2007 are not supported:
• The MFRC631 I2C interface does not stretch the clock
• The MFRC631 I2C interface does not support the general call. This means that the
MFRC631 does not support a software reset
• The MFRC631 does not support the I2C device ID
• The implemented interface can only act in slave mode. Therefore no clock generation
and access arbitration is implemented in the MFRC631.
• High speed mode is not supported by the MFRC631
SDA is a bidirectional line, connected to a positive supply voltage via a pull-up resistor.
Both lines SDA and SCL are set to HIGH level if no data is transmitted. Data on the
I
2
C-bus can be transferred at data rates of up to 400 kbit/s in fast mode, up to 1 Mbit/s in
the fast mode+.
If the I
2
C interface is selected, a spike suppression according to the I
2
C interface
specification on SCL and SDA is automatically activated.
For timing requirements refer to Table 196 “
I
2
C-bus timing in fast mode and fast mode
plus”
8.4.4.2 I
2
C Data validity
Data on the SDA line shall be stable during the HIGH period of the clock. The HIGH state
or LOW state of the data line shall only change when the clock signal on SCL is LOW.
Fig 13. I
2
C-bus interface
001aam000
READER IC
SDA
SCL
PULL-UP
NETWORK
PULL-UP
NETWORK
MICROCONTROLLER