SH79F166APSLASH044PR datasheet(39/113 Pages) SINOWEALTH

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SH79F166A

7.8 Timer

7.8.1 Features

 The SH79F166A has four timers (Timer2, 3, 4, 5)

 Timer2 is compatible with the standard 8052 and has up or down counting and programmable clock output function

 Timer3 is a 16-bit auto-reload timer and can operate even in Power-Down mode

 Timer4 is a 16-bit auto-reload timer and can be selected as a baud-rate generator

 Timer5 is a 16-bit auto-reload timer

7.8.2 Timer2

The Timer 2 is implemented as a 16-bit register accessed as two cascaded data registers: TH2 and TL2. It is controlled by the

register T2CON and T2MOD. The Timer2 interrupt can be enabled by setting the ET2 bit in the IEN0 register. (Refer to Interrupt

Section for details)

C/T2

———

selects system clock (timer operation) or external pin T2 (counter operation) as the timer clock input. Setting TR2 allows

Timer 2/Counter 2 Data Register to increment by the selected input.

Timer2 Modes

Timer2 has 4 operating modes: Capture/Reload, Auto-reload mode with up or down counter, Baud Rate Generator and

Programmable clock-output. These modes are selected by the combination of RCLK, TCLK and CP/RL2.

Table 7.25 Timer2 Mode select

C/T2

———

T2OE

DCEN

TR2

CP/RL2 RCLK

TCLK

Mode

16 bit capture

16 bit auto-reload timer

Baud-Rate generator

Programmable clock-output only

Programmable clock-output, with Baud-rate

generator

Not recommending

Timer2 stop, the T2EX path still enable

Mode0: 16 bit Capture

In the capture mode, two options are selected by bit EXEN2 in T2CON.

If EXEN2 = 0, Timer2 is a 16-bit timer or counter which will set TF2 on overflow to generate an interrupt if ET2 is enabled.

If EXEN2 = 1, Timer2 performs the same operation, but a 1-to-0 transition at external input T2EX also causes the current value

in TH2 and TL2 to be captured into RCAP2H and RCAP2L respectively, In addition, a 1-to-0 transition at T2EX causes bit EXF2

in T2CON to be set. The EXF2 bit, like TF2, can also generate an interrupt if ET2 is enabled.

0:Switch Off

1:Switch On

Block Diagram of 16 bit Capcture mode (Mode 0) of Timer2

Overflow flag

RCAP2H

RCAP2L

TL2

TH2

TF2

EXF2

0:Switch Off

1:Switch On

External falling

edge flag

Increment Mode

C/T2

Interrupt

Request

System Clock

TR2

EXEN2

CP / RL2

T2EX

SH79F166AP/044PR Datasheet(PDF) 39 Page - SINOWEALTH Electronic Ltd

SH79F166AP/044PR Datasheet(HTML) 39 Page - SINOWEALTH Electronic Ltd

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