mfrc522 NXP Semiconductors, mfrc522 Datasheet - Page 37

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

NXP Semiconductors
112132
Product data sheet
9.2.3.10 TMode Register, TPrescaler Register
Defines settings for the timer.
Remark: The Prescaler value is split over two registers.
Table 91:
Table 92:
Table 93:
Table 94:
Bit
7
6 to 5
4
3 to 0
Bit
7 to 0
Symbol
Access
Symbol
Access
Rights
Rights
Bit
Bit
Symbol
TAuto
TGated
TAutoRestart
TPrescaler_Hi Defines higher 4 bits for TPrescaler.
Symbol
TPrescaler_Lo Defines lower 8 bits for TPrescaler.
TModeReg register (address 2Ah); reset value: 00h
Description of TModeReg bits
TPrescalerReg register (address 2Bh); reset value: 00h
Description of TPrescalerReg bits
TAuto
r/w
7
7
6
6
Rev. 3.2 — 22 May 2007
Description
transmission in all communication modes at all speeds. The timer stops
immediately after receiving the first data bit if the bit RxMultiple in the
register RxModeReg is not set.
If RxMultiple is set to logic 1, the timer never stops. In this case the
timer can be stopped by setting the bit TStopNow in register ControlReg
to logic 1.
Set to logic 0 indicates, that the timer is not influenced by the protocol.
The internal timer is running in gated mode.
Remark: In the gated mode, the bit TRunning is logic 1 when the timer
Value
00
01
10
11
TReloadValue, instead of counting down to zero.
Set to logic 0 the timer decrements to 0 and the bit TimerIRq is set to
logic 1.
The following formula is used to calculate f
For detailed description see
Description
The following formula is used to calculate f
For detailed description see
Set to logic 1, the timer starts automatically at the end of the
Set to logic 1, the timer automatically restart its count-down from
TGated
f
f
r/w
Timer
Timer
= 6.78 MHz/TPreScaler.
= 6.78 MHz/TPreScaler.
5
5
Description
Non gated mode
Gated by MFIN
Gated by AUX1
Gated by A3
is enabled by the register bits. This bit does not influence the
gating signal.
TAutoRestart
TPrescaler_Hi
r/w
4
4
r/w
Section 13 “Timer
Section 13 “Timer
3
3
Timer
Timer
TPrescaler_Hi
2
2
Contactless Reader IC
Unit”.
Unit”.
:
:
MFRC522
r/w
© NXP B.V. 2007. All rights reserved.
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