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 62 of 95
NXP Semiconductors
MFRC522
Standard performance MIFARE and NTAG frontend
9.3.3.11 TReloadReg register
Defines the 16-bit timer reload value.
Remark: The reload value bits are contained in two 8-bit registers.
9.3.3.12 TCounterValReg register
Contains the timer value.
Remark: The timer value bits are contained in two 8-bit registers.
Table 108. TPrescalerReg register bit descriptions
Bit Symbol Description
7 to 0 TPrescaler_Lo[7:0] defines the lower 8 bits of the TPrescaler value
The following formula is used to calculate the timer frequency if the
DemodReg register’s TPrescalEven bit is set to logic 0:
f
timer
= 13.56 MHz / (2*TPreScaler+1).
Where TPreScaler = [TPrescaler_Hi:TPrescaler_Lo] (TPrescaler
value on 12 bits) (Default TPrescalEven bit is logic 0)
The following formula is used to calculate the timer frequency if the
DemodReg register’s TPrescalEven bit inDemoReg is set to logic 1:
f
timer
= 13.56 MHz / (2*TPreScaler+2).
See Section 8.5 “
Timer unit”.
Table 109. TReloadReg (higher bits) register (address 2Ch); reset value: 00h bit allocation
Bit 7 6 5 4 3 2 1 0
Symbol TReloadVal_Hi[7:0]
Access R/W
Table 110. TReloadReg register higher bit descriptions
Bit Symbol Description
7 to 0 TReloadVal_Hi[7:0] defines the higher 8 bits of the 16-bit timer reload value
on a start event, the timer loads the timer reload value
changing this register affects the timer only at the next start event
Table 111. TReloadReg (lower bits) register (address 2Dh); reset value: 00h bit allocation
Bit 7 6 5 4 3 2 1 0
Symbol TReloadVal_Lo[7:0]
Access R/W
Table 112. TReloadReg register lower bit descriptions
Bit Symbol Description
7 to 0 TReloadVal_Lo[7:0] defines the lower 8 bits of the 16-bit timer reload value
on a start event, the timer loads the timer reload value
changing this register affects the timer only at the next start event