ST25R3918 datasheet(32/141 Pages) STMICROELECTRONICS

32 / 141 page

Application information

ST25R3918

32/141

DS13490 Rev 2

independent from whether or not a tag reply was detected. When a tag reply is being

processed during a timeout, no other action is taken and the reply is normally received.

In the opposite case, when no tag response is being processed, the receiver is

disabled.

The NRT can also be started using direct command Start No-response timer. The intention

of this command is to extend the No-response timer timeout beyond the range defined in the

No-response timer control registers. If this command is sent while the timer is running, it is

reset and restarted.

The NRT can be terminated using direct command Stop No-response Timer or Stop all

activities. The timer is terminated and no IRQ is sent. It is expected to be used in the

nrt_emv mode, when the incoming reception does not stop the No-response timer.

In the Passive target mode the No-response timer has no task and is not automatically

started.

General purpose (GP) timer

The triggering of the this timer is configured by setting the Timer and EMV control register. It

can be used to survey the duration of reception process (triggering by start of reception,

after SOF) or to time out the PCD to PICC response time (triggered by end of reception,

after EOF).

The GP timer can also be started by sending the direct command Start General purpose

timer. If this command is sent while the timer is running, it is reset and restarted.

Wake-up (WU) timer

This timer is primarily used in the Wake-up mode, it can be used by sending the direct

command Start Wake-up Timer. This command is accepted in any operation mode except

Wake-up mode. When this command is sent the RC oscillator, which is used as clock

source for wake-up timer is started, timeout is defined by setting the Wake-up timer control

The WU timer is used in the Power-down mode, in which other timers cannot be used

because the crystal oscillator, which is the clock source for the other timers, is not running.

Note that the tolerance of wake-up timer timeout is defined by tolerance of the RC oscillator.

In low-power bit-rate detection mode the WU timer is used for time out the temporary device

enable after the initial peer field on was detected.

4.2.6

A/D converter

The ST25R3918 contains an 8-bit successive approximation A/D converter. Inputs can be

multiplexed from different sources to be used in several direct commands and adjustment

procedures. The result of the last conversion is stored in the A/D converter output register.

Typical conversion time is 224/fc (16.5 µs).

The A/D converter has two operating modes, absolute and relative.



In absolute mode the low reference is 0 V and the high reference is 2 V. This means

that A/D converter input range is from 0 to 2V, 00h code means input is 0 V or lower,

FFh means that input is 2 V - 1 LSB or higher, LSB being 7.8125 mV.



In relative mode low reference is 1/11 of VDD_A and high reference is 10/11 of VDD_A,

so the input range is from 1/11 VDD_A to 10/11 VDD_A.

ST25R3918 Datasheet(PDF) 32 Page - STMicroelectronics

ST25R3918 Datasheet(HTML) 32 Page - STMicroelectronics

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 ...More

Datasheet Download

Link URL