AT87F52-12AC ATMEL [ATMEL Corporation], AT87F52-12AC Datasheet - Page 3

• Manufacturer Part Number: AT87F52-12AC
• Description: 8-Bit Microcontroller with 8K Bytes QuickFlash
• Manufacturer: ATMEL [ATMEL Corporation]

The AT87F52 provides the following standard features: 8K
bytes of QuickFlash, 256 bytes of RAM, 32 I/O lines, three
16-bit timer/counters, a six-vector two-level interrupt archi-
tecture, a full duplex serial port, on-chip oscillator, and
clock circuitry. In addition, the AT87F52 is designed with
static logic for operation down to zero frequency and sup-
ports two software selectable power saving modes. The
Idle Mode stops the CPU while allowing the RAM,
timer/counters, serial port, and interrupt system to continue
functioning. The Power Down Mode saves the RAM con-
tents but freezes the oscillator, disabling all other chip func-
tions until the next hardware reset.
Pin Description
V
Supply voltage.
GND
Ground.
Port 0
Port 0 is an 8-bit open drain bidirectional I/O port. As an
output port, each pin can sink eight TTL inputs. When 1s
are written to port 0 pins, the pins can be used as high-
impedance inputs.
Port 0 can also be configured to be the multiplexed low-
order address/data bus during accesses to external pro-
gram and data memory. In this mode, P0 has internal pul-
lups.
Port 0 also receives the code bytes during QuickFlash pro-
gramming and outputs the code bytes during program veri-
fication. External pullups are required during program verifi-
cation.
Port 1
Port 1 is an 8-bit bidirectional I/O port with internal pullups.
The Port 1 output buffers can sink/source four TTL inputs.
When 1s are written to Port 1 pins, they are pulled high by
the internal pullups and can be used as inputs. As inputs,
Port 1 pins that are externally being pulled low will source
current (I
In addition, P1.0 and P1.1 can be configured to be the
timer/counter 2 external count input (P1.0/T2) and the
timer/counter 2 trigger input (P1.1/T2EX), respectively, as
shown in the following table.
Port 1 also receives the low-order address bytes during
QuickFlash programming and verification.
Port Pin
P1.0
P1.1
CC
IL
) because of the internal pullups.
Alternate Functions
T2 (external count input to Timer/Counter 2),
clock-out
T2EX (Timer/Counter 2 capture/reload trigger
and direction control)
Port 2
Port 2 is an 8-bit bidirectional I/O port with internal pullups.
The Port 2 output buffers can sink/source four TTL inputs.
When 1s are written to Port 2 pins, they are pulled high by
the internal pullups and can be used as inputs. As inputs,
Port 2 pins that are externally being pulled low will source
current (I
Port 2 emits the high-order address byte during fetches
from external program memory and during accesses to
external data memory that use 16-bit addresses (MOVX @
DPTR). In this application, Port 2 uses strong internal pul-
lups when emitting 1s. During accesses to external data
memory that use 8-bit addresses (MOVX @ RI), Port 2
emits the contents of the P2 Special Function Register.
Port 2 also receives the high-order address bits and some
control signals during QuickFlash programming and verifi-
cation.
Port 3
Port 3 is an 8-bit bidirectional I/O port with internal pullups.
The Port 3 output buffers can sink/source four TTL inputs.
When 1s are written to Port 3 pins, they are pulled high by
the internal pullups and can be used as inputs. As inputs,
Port 3 pins that are externally being pulled low will source
current (I
Port 3 also serves the functions of various special features
of the AT89C51, as shown in the following table.
Port 3 also receives some control signals for QuickFlash
programming and verification.
RST
Reset input. A high on this pin for two machine cycles while
the oscillator is running resets the device.
ALE/PROG
Address Latch Enable is an output pulse for latching the
low byte of the address during accesses to external mem-
ory. This pin is also the program pulse input (PROG) during
QuickFlash programming.
In normal operation, ALE is emitted at a constant rate of 1/6
the oscillator frequency and may be used for external tim-
ing or clocking purposes. Note, however, that one ALE
Port Pin
P3.0
P3.1
P3.2
P3.3
P3.4
P3.5
P3.6
P3.7
IL
IL
) because of the internal pullups.
) because of the pullups.
Alternate Functions
RXD (serial input port)
TXD (serial output port)
INT0 (external interrupt 0)
INT1 (external interrupt 1)
T0 (timer 0 external input)
T1 (timer 1 external input)
WR (external data memory write strobe)
RD (external data memory read strobe)
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