P89LV51RD2BA PHILIPS [NXP Semiconductors], P89LV51RD2BA Datasheet - Page 27

• Manufacturer Part Number: P89LV51RD2BA
• Description: 8-bit 80C51 3 V low power 64 kB Flash microcontroller with 1 kB RAM
• Manufacturer: PHILIPS [NXP Semiconductors]

Philips Semiconductors
9397 750 14342
Product data
7.3 Timers/counters 0 and 1
Table 13:
The two 16-bit Timer/Counter registers: Timer 0 and Timer 1 can be configured to
operate either as timers or event counters (see
In the ‘Timer’ function, the register is incremented every machine cycle. Thus, one
can think of it as counting machine cycles. Since a machine cycle consists of six
oscillator periods, the count rate is
In the ‘Counter’ function, the register is incremented in response to a 1-to-0 transition
at its corresponding external input pin, T0 or T1. In this function, the external input is
sampled once every machine cycle.
When the samples show a high in one cycle and a low in the next cycle, the count is
incremented. The new count value appears in the register in the machine cycle
following the one in which the transition was detected. Since it takes two machine
cycles (12 oscillator periods) for 1-to-0 transition to be recognized, the maximum
count rate is
of the external input signal, but to ensure that a given level is sampled at least once
before it changes, it should be held for at least one full machine cycle. In addition to
the ‘Timer’ or ‘Counter’ selection, Timer 0 and Timer 1 have four operating modes
from which to select.
The ‘Timer’ or ‘Counter’ function is selected by control bits C/T in the Special
Function Register TMOD. These two Timer/Counters have four operating modes,
which are selected by bit-pairs (M1, M0) in TMOD. Modes 0, 1, and 2 are the same
for both Timers/Counters. Mode 3 is different. The four operating modes are
described in the following text.
IAP function
Read Security Bit, Double Clock,
SoftICE
Read Security Bit, Double Clock,
SoftICE
Erase sector
IAP function calls
1
12
of the oscillator frequency. There are no restrictions on the duty cycle
Rev. 04 — 02 December 2004
…continued
IAP call parameters
Input parameters:
ACC = 07h
Return parameter(s):
ACC = 000 S/N-match 0 SB 0 DBL_CLK
Input parameters:
ACC = 07h
Return parameter(s):
ACC = 00 SoftICE S/N-match 0 SB 0 DBL_CLK
Input parameters:
R1 = 08h
DPH = sector address high byte
DPL = sector address low byte
Return parameter(s):
ACC = 00 = pass
ACC = !00 = fail
1
6
P89LV51RB2/RC2/RD2
of the oscillator frequency.
8-bit microcontrollers with 80C51 core
Table 14
© Koninklijke Philips Electronics N.V. 2004. All rights reserved.
and
Table
15).
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