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87C31X2 Schematic ( PDF Datasheet ) - NXP Semiconductors

Teilenummer 87C31X2
Beschreibung 80C51 8-bit microcontroller family 4K/8K/16K/32K ROM/OTP 128B/256B RAM low voltage 2.7 to 5.5 V/ low power/ high speed 30/33 MHz
Hersteller NXP Semiconductors
Logo NXP Semiconductors Logo 




Gesamt 57 Seiten
87C31X2 Datasheet, Funktion
INTEGRATED CIRCUITS
80C31X2/32X2
80C51X2/52X2/54X2/58X2
87C51X2/52X2/54X2/58X2
80C51 8-bit microcontroller family
4K/8K/16K/32K ROM/OTP
128B/256B RAM
low voltage (2.7 to 5.5 V), low power, high speed (30/33 MHz)
Preliminary data
2001 Sep 24
Philips
Semiconductors






87C31X2 Datasheet, Funktion
Philips Semiconductors
80C51 8-bit microcontroller family
4K/8K/16K/32K ROM/OTP, low voltage (2.7 to 5.5 V),
low power, high speed (30/33 MHz)
BLOCK DIAGRAM 1
Preliminary data
80C3xX2; 80C5xX2;
87C5xX2
Accelerated 80C51 CPU
(12-clk mode, 6-clk mode)
Crystal or
Resonator
0K / 4K / 8K / 16K /
32K Byte
CODE ROM / EPROM
128 / 256 Byte
Data RAM
Port 3
Configurable I/Os
Port 2
Configurable I/Os
Port 1
Configurable I/Os
Port 0
Configurable I/Os
Oscillator
Full-duplex enhanced
UART
Timer 0
Timer 1
Timer 2
su01579
2001 Sep 24
6

6 Page









87C31X2 pdf, datenblatt
Philips Semiconductors
80C51 8-bit microcontroller family
4K/8K/16K/32K ROM/OTP, low voltage (2.7 to 5.5 V),
low power, high speed (30/33 MHz)
Preliminary data
80C3xX2; 80C5xX2;
87C5xX2
Clock Control Register (CKCON)
This device provides control of the 6-clock/12-clock mode by an
SFR bit (bit X2 in register CKCON). When this bit is set to 0,
12-clock mode is activated. By setting this bit to 1, the system is
switching to 6-clock mode. Having this option implemented as SFR
bit, it can be accessed anytime and changed to either value. An
important thing to have in mind is that changing X2 from 0 to 1 will
result in executing user code at twice the speed, since all system
time intervals will be divided by 2. Changing from 6-clock to 12-clock
mode will slow down running code by a factor of 2.
Programmable Clock-Out
A 50% duty cycle clock can be programmed to be output on P1.0.
This pin, besides being a regular I/O pin, has two alternate
functions. It can be programmed:
1. to input the external clock for Timer/Counter 2, or
2. to output a 50% duty cycle clock ranging from 61 Hz to 4 MHz at
a 16 MHz operating frequency.
To configure the Timer/Counter 2 as a clock generator, bit C/T2 (in
T2CON) must be cleared and bit T20E in T2MOD must be set. Bit
TR2 (T2CON.2) also must be set to start the timer.
The Clock-Out frequency depends on the oscillator frequency and
the reload value of Timer 2 capture registers (RCAP2H, RCAP2L)
as shown in this equation:
Oscillator Frequency
4 (65536 * RCAP2H, RCAP2L)
Where:
(RCAP2H,RCAP2L) = the content of RCAP2H and RCAP2L
taken as a 16-bit unsigned integer.
In the Clock-Out mode Timer 2 roll-overs will not generate an
interrupt. This is similar to when it is used as a baud-rate generator.
It is possible to use Timer 2 as a baud-rate generator and a clock
generator simultaneously. Note, however, that the baud-rate and the
Clock-Out frequency will be the same.
TIMER 0 AND TIMER 1 OPERATION
Timer 0 and Timer 1
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.
Mode 0
Putting either Timer into Mode 0 makes it look like an 8048 Timer,
which is an 8-bit Counter with a divide-by-32 prescaler. Figure 2
shows the Mode 0 operation.
In this mode, the Timer register is configured as a 13-bit register. As
the count rolls over from all 1s to all 0s, it sets the Timer interrupt
flag TFn. The counted input is enabled to the Timer when TRn = 1
and either GATE = 0 or INTn = 1. (Setting GATE = 1 allows the
Timer to be controlled by external input INTn, to facilitate pulse width
measurements). TRn is a control bit in the Special Function Register
TCON (Figure 3).
The 13-bit register consists of all 8 bits of THn and the lower 5 bits
of TLn. The upper 3 bits of TLn are indeterminate and should be
ignored. Setting the run flag (TRn) does not clear the registers.
Mode 0 operation is the same for Timer 0 as for Timer 1. There are
two different GATE bits, one for Timer 1 (TMOD.7) and one for Timer
0 (TMOD.3).
Mode 1
Mode 1 is the same as Mode 0, except that the Timer register is
being run with all 16 bits.
Mode 2
Mode 2 configures the Timer register as an 8-bit Counter (TLn) with
automatic reload, as shown in Figure 4. Overflow from TLn not only
sets TFn, but also reloads TLn with the contents of THn, which is
preset by software. The reload leaves THn unchanged.
Mode 2 operation is the same for Timer 0 as for Timer 1.
Mode 3
Timer 1 in Mode 3 simply holds its count. The effect is the same as
setting TR1 = 0.
Timer 0 in Mode 3 establishes TL0 and TH0 as two separate
counters. The logic for Mode 3 on Timer 0 is shown in Figure 5. TL0
uses the Timer 0 control bits: C/T, GATE, TR0, and TF0 as well as
pin INT0. TH0 is locked into a timer function (counting machine
cycles) and takes over the use of TR1 and TF1 from Timer 1. Thus,
TH0 now controls the “Timer 1” interrupt.
Mode 3 is provided for applications requiring an extra 8-bit timer on
the counter. With Timer 0 in Mode 3, an 80C51 can look like it has
three Timer/Counters. When Timer 0 is in Mode 3, Timer 1 can be
turned on and off by switching it out of and into its own Mode 3, or
can still be used by the serial port as a baud rate generator, or in
fact, in any application not requiring an interrupt.
2001 Sep 24
12

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