CR14_10 STMICROELECTRONICS [STMicroelectronics], CR14_10 Datasheet - Page 19
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CR14_10
Manufacturer Part Number
CR14_10
Description
ISO14443 type-B contactless coupler chip with anti-collision and CRC management
Manufacturer
STMICROELECTRONICS [STMicroelectronics]
Datasheet
1.CR14_10.pdf
(47 pages)
CR14
4.6
Figure 7.
BUS Master
CR14 WRITE
BUS Slave
CR14 I²C write operations
The bus master sends a START condition, followed by a Device Select Code and the R/W
bit set to ’0’. The CR14 that corresponds to the Device Select Code, acknowledges and
waits for the bus master to send the Byte address of the register that is to be written to. After
receipt of the address, the CR14 returns another ACK, and waits for the bus master to send
the data Bytes that are to be written.
In the CR14 I²C Write mode, the bus master may sends one or more data Bytes depending
on the selected register.
The CR14 replies with an ACK after each data Byte received. The bus master terminates
the transfer by generating a STOP condition.
The STOP condition at the end of a Write access to the Input/Output Frame Register causes
the Radio Frequency data exchange between the CR14 and the PICC to be started.
During the Radio Frequency data exchange, the CR14 disconnects itself from the I²C bus.
The time (t
command format. To know when the exchange is complete, the bus master uses an ACK
polling sequence as shown in
●
●
●
CR14 I²C write mode sequence
Initial condition: a Radio Frequency data exchange is in progress.
Step 1: the master issues a START condition followed by the first Byte of the new
instruction (Device Select Code plus R/W bit).
Step 2: if the CR14 is busy, no ACK is returned and the master goes back to Step 1. If
the CR14 has completed the Radio Frequency data exchange, it responds with an
ACK, indicating that it is ready to receive the second part of the next instruction (the
first Byte of this instruction being sent during Step 1).
DEV SEL
RFEX
R/W
) needed to complete the exchange is not fixed as it depends on the PICC
ACK
BYTE ADDR
ACK
Figure
Doc ID 11922 Rev 2
DATA 1
8. It consists of the following:
ACK
DATA 2
ACK
DATA 3
CR14 I²C protocol description
ACK
DATA N
ACK
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