AT89LP213 datasheet(30/98 Pages) ATMEL

30 / 98 page

3538D–MICRO–10/09

AT89LP213/214

14.2

Mode 1 – 16-bit Auto-Reload Timer/Counter

In Mode 1 the Timers are configured for 16-bit auto-reload. The Timer register is run with all

16 bits. The 16-bit reload value is stored in the high and low reload registers (RH1/RL1). The

clock is applied to the combined high and low timer registers (TH1/TL1). As clock pulses are

received, the timer counts up: 0000H, 0001H, 0002H, etc. An overflow occurs on the FFFFH-to-

0000H transition, upon which the timer register is reloaded with the value from RH1/RL1 and the

overflow flag bit in TCON is set. See Figure 14-2. The reload registers default to 0000H, which

gives the full 16-bit timer period compatible with the standard 8051. Mode 1 operation is the

same for Timer/Counter 0.

Figure 14-2. Timer/Counter 1 Mode 1: 16-bit Auto-reload

14.3

Mode 2 – 8-bit Auto-reload Timer/Counter

Mode 2 configures the Timer register as an 8-bit Counter (TL1) with automatic reload, as shown

in Figure 14-3. Overflow from TL1 not only sets TF1, but also reloads TL1 with the contents of

TH1, which is preset by software. The reload leaves TH1 unchanged. Mode 2 operation is the

same for Timer/Counter 0.

Figure 14-3. Timer/Counter 1 Mode 2: 8-bit Auto-reload

Note:

RH1/RL1 are not required by Timer 1 during Mode 2 and may be used as temporary storage

registers.

Mode 1:

Time-out Period

65536

RH0 RL0

}

–

()

Oscillator Frequency

---------------------------------------------------------

TPS

()

OSC

T1 Pin

TR1

GATE

INT1 Pin

TL1

(8 Bits)

Control

Interrupt

C/T = 0

C/T =1

TH1

(8 Bits)

TF1

RL1

(8 Bits)

RH1

(8 Bits)

Reload

÷TPS

Mode 2:

Time-out Period

256

TH0

–

()

Oscillator Frequency

-------------------------------------------------------

TPS

()

OSC

T1 Pin

TR1

GATE

TF1

TL1

(8 Bits)

TH1

(8 Bits)

Control

Reload

Interrupt

INT0 Pin

C/T = 0

C/T = 1

÷TPS

AT89LP213 Datasheet(PDF) 30 Page - ATMEL Corporation

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