08-11-2012, 11:39 AM
8-bit Microcontroller with 2K Bytes Flash
[attachment=38536]
Features
• Compatible with MCS-51™ Products
• 2K Bytes of Reprogrammable Flash Memory
– Endurance: 1,000 Write/Erase Cycles
• 2.7V to 6V Operating Range
• Fully Static Operation: 0 Hz to 24 MHz
• Two-level Program Memory Lock
• 128 x 8-bit Internal RAM
• 15 Programmable I/O Lines
• Two 16-bit Timer/Counters
• Six Interrupt Sources
• Programmable Serial UART Channel
• Direct LED Drive Outputs
• On-chip Analog Comparator
• Low-power Idle and Power-down Modes
Description
The AT89C2051 is a low-voltage, high-performance CMOS 8-bit microcomputer with
2K bytes of Flash programmable and erasable read only memory (PEROM). The
device is manufactured using Atmel’s high-density nonvolatile memory technology
and is compatible with the industry-standard MCS-51 instruction set. By combining a
versatile 8-bit CPU with Flash on a monolithic chip, the Atmel AT89C2051 is a powerful
microcomputer which provides a highly-flexible and cost-effective solution to many
embedded control applications.
The AT89C2051 provides the following standard features: 2K bytes of Flash, 128
bytes of RAM, 15 I/O lines, two 16-bit timer/counters, a five vector two-level interrupt
architecture, a full duplex serial port, a precision analog comparator, on-chip oscillator
and clock circuitry. In addition, the AT89C2051 is designed with static logic for operation
down to zero frequency and supports 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 contents but freezes the oscillator disabling all other chip functions until the next
hardware reset.
Oscillator Characteristics
XTAL1 and XTAL2 are the input and output, respectively,
of an inverting amplifier which can be configured for use as
an on-chip oscillator, as shown in Figure 1. Either a quartz
crystal or ceramic resonator may be used. To drive the
device from an external clock source, XTAL2 should be left
unconnected while XTAL1 is driven as shown in Figure 2.
There are no requirements on the duty cycle of the external
clock signal, since the input to the internal clocking circuitry
is through a divide-by-two flip-flop, but minimum and maximum
voltage high and low time specifications must be
observed.
Special Function Registers
A map of the on-chip memory area called the Special Function
Register (SFR) space is shown in the table below.
Note that not all of the addresses are occupied, and unoccupied
addresses may not be implemented on the chip.
Read accesses to these addresses will in general return
random data, and write accesses will have an indeterminate
effect.
User software should not write 1s to these unlisted locations,
since they may be used in future products to invoke
new features. In that case, the reset or inactive values of
the new bits will always be 0.
Restrictions on Certain Instructions
The AT89C2051 and is an economical and cost-effective
member of Atmel’s growing family of microcontrollers. It
contains 2K bytes of flash program memory. It is fully compatible
with the MCS-51 architecture, and can be
programmed using the MCS-51 instruction set. However,
there are a few considerations one must keep in mind
when utilizing certain instructions to program this device.
All the instructions related to jumping or branching should
be restricted such that the destination address falls within
the physical program memory space of the device, which is
2K for the AT89C2051. This should be the responsibility of
the software programmer. For example, LJMP 7E0H
would be a valid instruction for the AT89C2051 (with 2K of
memory), whereas LJMP 900H would not.
IDLE MODE
In idle mode, the CPU puts itself to sleep while all the onchip
peripherals remain active. The mode is invoked by
software. The content of the on-chip RAM and all the special
functions registers remain unchanged during this
mode. The idle mode can be terminated by any enabled
interrupt or by a hardware reset.
P1.0 and P1.1 should be set to “0” if no external pullups are
used, or set to “1” if external pullups are used.
It should be noted that when idle is terminated by a hardware
reset, the device normally resumes program
execution, from where it left off, up to two machine cycles
before the internal reset algorithm takes control. On-chip
hardware inhibits access to internal RAM in this event, but
access to the port pins is not inhibited. To eliminate the
possibility of an unexpected write to a port pin when Idle is
terminated by reset, the instruction following the one that
invokes Idle should not be one that writes to a port pin or to
external memory.
Power-down Mode
In the power down mode the oscillator is stopped, and the
instruction that invokes power down is the last instruction
executed. The on-chip RAM and Special Function Registers
retain their values until the power down mode is
terminated. The only exit from power down is a hardware
reset. Reset redefines the SFRs but does not change the
on-chip RAM. The reset should not be activated before VCC
is restored to its normal operating level and must be held
active long enough to allow the oscillator to restart and
stabilize.
[attachment=38536]
Features
• Compatible with MCS-51™ Products
• 2K Bytes of Reprogrammable Flash Memory
– Endurance: 1,000 Write/Erase Cycles
• 2.7V to 6V Operating Range
• Fully Static Operation: 0 Hz to 24 MHz
• Two-level Program Memory Lock
• 128 x 8-bit Internal RAM
• 15 Programmable I/O Lines
• Two 16-bit Timer/Counters
• Six Interrupt Sources
• Programmable Serial UART Channel
• Direct LED Drive Outputs
• On-chip Analog Comparator
• Low-power Idle and Power-down Modes
Description
The AT89C2051 is a low-voltage, high-performance CMOS 8-bit microcomputer with
2K bytes of Flash programmable and erasable read only memory (PEROM). The
device is manufactured using Atmel’s high-density nonvolatile memory technology
and is compatible with the industry-standard MCS-51 instruction set. By combining a
versatile 8-bit CPU with Flash on a monolithic chip, the Atmel AT89C2051 is a powerful
microcomputer which provides a highly-flexible and cost-effective solution to many
embedded control applications.
The AT89C2051 provides the following standard features: 2K bytes of Flash, 128
bytes of RAM, 15 I/O lines, two 16-bit timer/counters, a five vector two-level interrupt
architecture, a full duplex serial port, a precision analog comparator, on-chip oscillator
and clock circuitry. In addition, the AT89C2051 is designed with static logic for operation
down to zero frequency and supports 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 contents but freezes the oscillator disabling all other chip functions until the next
hardware reset.
Oscillator Characteristics
XTAL1 and XTAL2 are the input and output, respectively,
of an inverting amplifier which can be configured for use as
an on-chip oscillator, as shown in Figure 1. Either a quartz
crystal or ceramic resonator may be used. To drive the
device from an external clock source, XTAL2 should be left
unconnected while XTAL1 is driven as shown in Figure 2.
There are no requirements on the duty cycle of the external
clock signal, since the input to the internal clocking circuitry
is through a divide-by-two flip-flop, but minimum and maximum
voltage high and low time specifications must be
observed.
Special Function Registers
A map of the on-chip memory area called the Special Function
Register (SFR) space is shown in the table below.
Note that not all of the addresses are occupied, and unoccupied
addresses may not be implemented on the chip.
Read accesses to these addresses will in general return
random data, and write accesses will have an indeterminate
effect.
User software should not write 1s to these unlisted locations,
since they may be used in future products to invoke
new features. In that case, the reset or inactive values of
the new bits will always be 0.
Restrictions on Certain Instructions
The AT89C2051 and is an economical and cost-effective
member of Atmel’s growing family of microcontrollers. It
contains 2K bytes of flash program memory. It is fully compatible
with the MCS-51 architecture, and can be
programmed using the MCS-51 instruction set. However,
there are a few considerations one must keep in mind
when utilizing certain instructions to program this device.
All the instructions related to jumping or branching should
be restricted such that the destination address falls within
the physical program memory space of the device, which is
2K for the AT89C2051. This should be the responsibility of
the software programmer. For example, LJMP 7E0H
would be a valid instruction for the AT89C2051 (with 2K of
memory), whereas LJMP 900H would not.
IDLE MODE
In idle mode, the CPU puts itself to sleep while all the onchip
peripherals remain active. The mode is invoked by
software. The content of the on-chip RAM and all the special
functions registers remain unchanged during this
mode. The idle mode can be terminated by any enabled
interrupt or by a hardware reset.
P1.0 and P1.1 should be set to “0” if no external pullups are
used, or set to “1” if external pullups are used.
It should be noted that when idle is terminated by a hardware
reset, the device normally resumes program
execution, from where it left off, up to two machine cycles
before the internal reset algorithm takes control. On-chip
hardware inhibits access to internal RAM in this event, but
access to the port pins is not inhibited. To eliminate the
possibility of an unexpected write to a port pin when Idle is
terminated by reset, the instruction following the one that
invokes Idle should not be one that writes to a port pin or to
external memory.
Power-down Mode
In the power down mode the oscillator is stopped, and the
instruction that invokes power down is the last instruction
executed. The on-chip RAM and Special Function Registers
retain their values until the power down mode is
terminated. The only exit from power down is a hardware
reset. Reset redefines the SFRs but does not change the
on-chip RAM. The reset should not be activated before VCC
is restored to its normal operating level and must be held
active long enough to allow the oscillator to restart and
stabilize.