Data Sheet

MFRC522 All information provided in this document is subject to legal disclaimers. © NXP Semiconductors N.V. 2016. All rights reserved.
Product data sheet
COMPANY PUBLIC
Rev. 3.9 — 27 April 2016
112139 12 of 95
NXP Semiconductors
MFRC522
Standard performance MIFARE and NTAG frontend
8.1.3.2 Selectable UART transfer speeds
The internal UART interface is compatible with an RS232 serial interface.
The default transfer speed is 9.6 kBd. To change the transfer speed, the host controller
must write a value for the new transfer speed to the SerialSpeedReg register. Bits
BR_T0[2:0] and BR_T1[4:0] define the factors for setting the transfer speed in the
SerialSpeedReg register.
The BR_T0[2:0] and BR_T1[4:0] settings are described in Table 9
. Examples of different
transfer speeds and the relevant register settings are given in Table 10
.
[1] The resulting transfer speed error is less than 1.5 % for all described transfer speeds.
The selectable transfer speeds shown in Table 10 are calculated according to the
following equations:
If BR_T0[2:0] = 0:
(1)
If BR_T0[2:0] > 0:
(2)
Remark: Transfer speeds above 1228.8 kBd are not supported.
Table 9. BR_T0 and BR_T1 settings
BR_Tn Bit 0 Bit 1 Bit 2 Bit 3 Bit 4 Bit 5 Bit 6 Bit 7
BR_T0 factor11248163264
BR_T1 range 1 to 32 33 to 64 33 to 64 33 to 64 33 to 64 33 to 64 33 to 64 33 to 64
Table 10. Selectable UART transfer speeds
Transfer speed (kBd) SerialSpeedReg value Transfer speed accuracy
(%)
[1]
Decimal Hexadecimal
7.2 250 FAh 0.25
9.6 235 EBh 0.32
14.4 218 DAh 0.25
19.2 203 CBh 0.32
38.4 171 ABh 0.32
57.6 154 9Ah 0.25
115.2 122 7Ah 0.25
128 116 74h 0.06
230.4 90 5Ah 0.25
460.8 58 3Ah 0.25
921.6 28 1Ch 1.45
1228.8 21 15h 0.32
transfer speed
27.12 10
6

BR_T0 1+
--------------------------------
=
transfer speed
27.12 10
6

BR_T1 33+
2
BR_T0 1–
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