AT89LP213 datasheet(29/98 Pages) ATMEL

29 / 98 page

3538D–MICRO–10/09

AT89LP213/214

However, the inputs may be exercised in software by toggling the P3.4 and P3.5 bits in the

Port 3 register.

Furthermore, the Timer or Counter functions for Timer 0 and Timer 1 have four operating modes:

variable width timer, 16-bit auto-reload timer, 8-bit auto-reload timer, and split timer. The control

bits C/T in the Special Function Register TMOD select the Timer or Counter function. The bit

pairs (M1, M0) in TMOD select the operating modes.

14.1

Mode 0 – Variable Width Timer/Counter

Both Timers in Mode 0 are 8-bit Counters with a variable prescaler. The prescaler may vary from

1 to 8 bits depending on the PSC bits in TCONB, giving the timer a range of 9 to 16 bits.

By default the timer is configured as a 13-bit timer compatible to Mode 0 in the standard 8051.

Figure 14-1 shows the Mode 0 operation as it applies to Timer 1 in 13-bit mode. As the count

rolls over from all “1”s to all “0”s, it sets the Timer interrupt flag TF1. The counter input is enabled

to the Timer when TR1 = 1 and either GATE = 0 or INT1 = 1. Setting GATE = 1 allows the Timer

to be controlled by external input INT1, to facilitate pulse width measurements. TR1 is a control

bit in the Special Function Register TCON. GATE is in TMOD. The 13-bit register consists of all

8 bits of TH1 and the lower 5 bits of TL1. The upper 3 bits of TL1 are indeterminate and should

be ignored. Setting the run flag (TR1) does not clear the registers.

Note:

RH1/RL1 are not required by Timer 1 during Mode 0 and may be used as temporary storage

registers.

Figure 14-1. Timer/Counter 1 Mode 0: Variable Width Counter

Mode 0 operation is the same for Timer 0 as for Timer 1, except that TR0, TF0 and INT0 replace

the corresponding Timer 1 signals in Figure 14-1. There are two different GATE bits, one for

Timer 1 (TMOD.7) and one for Timer 0 (TMOD.3). The INT0 and INT1 pins are shared with the

XTAL oscillator. They may only be used for the GATE function when using the internal RC oscil-

lator as the system clock.

Mode 0:

Time-out Period

256

PSC0

Oscillator Frequency

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

TPS

()

OSC

T1 Pin

TR1

GATE

INT1 Pin

TL1

(8 Bits)

Control

Interrupt

C/T = 0

C/T = 1

PSC1

TH1

(8 Bits)

TF1

÷TPS

AT89LP213 Datasheet(PDF) 29 Page - ATMEL Corporation

AT89LP213 Datasheet(HTML) 29 Page - ATMEL Corporation

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