CRX14_05 Datasheet, PDF (17/40 Pages) STMicroelectronics – Low Cost ISO14443 type-B Contactless Coupler Chip with Anti-Collision, CRC Management and Anti-Clone Function

CRX14
APPLYING THE I²C PROTOCOL TO THE CRX14 REGISTERS
I²C Parameter Register Protocol
Figure 11. shows how new data is written to the
Parameter Register. The new value becomes ac-
tive after the I²C STOP condition.
Figure 12. shows how to read the Parameter Reg-
ister contents. The CRX14 sends and re-sends the
Parameter Register contents until it receives a
NoACK from the I²C Host.
The CRX14 supports the I²C Current Address and
Random Address Read modes. The Current Ad-
dress Read mode can be used if the previous
command was issued to the register where the
Read is to take place.
Figure 11. Host-to-CRX14 Transfer: I²C Write to Parameter Register
S
T
Bus Master
A
R
T
R/W
Device Select
Code
Parameter Register
Address
S
Register Byte
Value
T
O
P
CRX14 Write
1 0 1 0X X X
00h
data
Bus Slave
ACK
ACK
ACK
ai09240
Figure 12. CRX14-to-Host Transfer: I²C Random Address Read from Parameter Register
R
E
S
R/W
T
S
T
R/W
Bus Master ^A
R
T
Device Select
Code
Parameter Register ^A Device Select
Address
R
Code
T
NoACK
S
T
O
P
CRX14 Read
1 0 1 0X X X
00h
1 0 1 0X X X
data
Bus Slave
ACK
ACK
Register Byte
ACK
Value
ai09241
Figure 13. CRX14-to-Host Transfer: I²C Current Address Read from Parameter Register
Bus Master
CRX14 Read
Bus Slave
S
R/W
T
A _{Device Select}
R
Code
T
NoACK
S
T
O
P
1 0 1 0X X X
data
ACK
Register Byte
Value
ai09242
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