Maxim-integrated MAX31782 Manual do Utilizador descarregar pdf (Página 105)

Maxim Integrated 12-3

MAX31782 User’s Guide

Revision 0; 8/11

12.1.1 Auto-Reload Mode

The 16-bit auto-reload mode of Timer B is established by clearing the CP/RLB bit to 0. In this mode, the timer performs

a simple 16-bit timer or counter function that is reset to 0000h when a match between the Timer B count value register

(TB0V) and the Timer B capture/reload register (TB0R) occurs. A block diagram of auto-reload mode is illustrated in

Figure 12-1. If the C/TB bit is a logic 0, the timer’s input clock is a prescaled system clock. When C/TB is a logic 1,

pulses on the TBA pin are counted. As in all modes, counting or timing is enabled or disabled with the TRB bit.

When enabled in auto-reload mode, the Timer B begins counting up from the current value contained in the TB0V

to 1, which can generate an interrupt if enabled. Also when this match is made, the timer reloads the TB0V register with

0000h and continues timing or counting from 0000h. The reload value contained in the TB0R register is preloaded by

software. The TB0R register cannot be used for the capture function while also performing auto-reload.

While in auto-reload mode, the Timer B can also be forced to reload the TB0V register with 0000h using the TBB pin. If

the EXENB bit is set to 1, a 1 to 0 transition (falling edge) on the TBB pin causes a reload. If the EXENB bit is cleared

to 0, the TBB pin is ignored.

Figure 12-1. Auto-Reload Mode Block Diagram

SYSTEM

CLOCK

CLOCK PRESCALER

TBPS[2:0]

CLK

RELOAD

TBA PIN

TRB

TBB PIN

EXENB

FALLING

EDGE

15 0

TB0R

COMPARE

TB0V

0000h

EXFB = 1

TFB = 1

ETB

TIMER B

INTERRUPT

C/TB

1 2 ... 100 101 102 103 104 105 106 107 108 109 110 ... 222 223

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Maxim-integrated MAX31782 Manual do Utilizador Página 105