mfrc522 NXP Semiconductors, mfrc522 Datasheet - Page 49

• Manufacturer Part Number: mfrc522
• Description: Contactless Reader Ic
• Manufacturer: NXP Semiconductors

NXP Semiconductors
112132
Product data sheet
10.3.2 Selection of the transfer speeds
The internal UART interface is compatible to an RS232 serial interface.
Table 140 “Selectable transfer speeds”
and relevant register settings.
The resulting transfer speed error is less than 1.5% for all described transfer speeds.
The default transfer speed is 9.6 kbit/s.
To change the transfer speed, the host controller has to write a value for the new transfer
speed to the register SerialSpeedReg. The bits BR_T0 and BR_T1 define factors to set
the transfer speed in the SerialSpeedReg.
Table 139 “Settings of BR_T0 and BR_T1”
Table 139: Settings of BR_T0 and BR_T1
Table 140: Selectable transfer speeds
The selectable transfer speeds as shown in
calculated according to the following formulas:
Remark: Transfer speeds above 1228.8 k are not supported.
BR_T0
factor BR_T0
range BR_T1
if BR_T0=0: transfer speed = 27.12 MHz/(BR_T1+1)
if BR_T0>0: transfer speed = 27.12 MHz/(BR_T1 +33)/2^(BR_T0 -1)
Transfer Speed [bit/s]
1228.8 k
115.2 k
230.4 k
460.8 k
921.6 k
14.4 k
19.2 k
38.4 k
57.6 k
128 k
7.2 k
9.6 k
1 to 32
0
1
Rev. 3.2 — 22 May 2007
33 to 64 33 to 64 33 to 64 33 to 64 33 to 64 33 to 64 33 to 64
1
1
decimal
250
235
218
203
171
154
122
116
90
58
28
21
SerialSpeedReg
2
2
describes examples for different transfer speeds
describes the settings of BR_T0 and BR_T1.
Table 140 “Selectable transfer speeds”
3
4
heximal
DAh
CBh
FAh
EBh
ABh
9Ah
7Ah
5Ah
3Ah
1Ch
74h
15h
4
8
Transfer Speed Accuracy
16
Contactless Reader IC
5
MFRC522
© NXP B.V. 2007. All rights reserved.
-0.25%
-0.25%
-0.25%
-0.25%
-0.06%
-0.25%
-0.25%
0.32%
0.32%
0.32%
1.45%
0.32%
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