P89LPC921FDH ,8-bit microcontrollers with two-clock 80C51 core 2 kB/4 kB/8 kB 3 V low-power Flash with 256-byte data RAMP89LPC920/921/9228-bit microcontrollers with two-clock 80C51 core2 kB/4 kB/8 kB 3 V low-power Flash ..
P89LPC922FDH ,8-bit microcontrollers with two-clock 80C51 core 2 kB/4 kB/8 kB 3 V low-power Flash with 256-byte data RAMP89LPC920/921/9228-bit microcontrollers with two-clock 80C51 core2 kB/4 kB/8 kB 3 V low-power Flash ..
P89LPC922FN ,8-bit microcontrollers with two-clock 80C51 core 2 kB/4 kB/8 kB 3 V low-power Flash with 256-byte data RAMfeatures■ 2 kB/4 kB/8 kB Flash code memory with 1 kB erasable sectors, 64-byte erasablepage size, a ..
P89LPC922FN ,8-bit microcontrollers with two-clock 80C51 core 2 kB/4 kB/8 kB 3 V low-power Flash with 256-byte data RAMP89LPC920/921/922/92218-bit microcontrollers with two-clock 80C51 core2 kB/4 kB/8 kB 3 V low-power ..
P89LPC924FDH ,8-bit microcontrollers with accelerated two-clock 80C51 core 4 kB/8 kB 3 V low-power Flash with 8-bit A/D converterapplicationsdemanding high-integration, low cost solutions over a wide range of performancerequirem ..
P89LPC924FDH ,8-bit microcontrollers with accelerated two-clock 80C51 core 4 kB/8 kB 3 V low-power Flash with 8-bit A/D converterapplicationsdemanding high-integration, low cost solutions over a wide range of performancerequirem ..
PCB80C562-16WP , Single-chip 8-bit microcontroller
PCB80C562-16WP , Single-chip 8-bit microcontroller
PCD-124D1MH , 15 Amp Low Profile Power PC Board Relay
PCD-148D1MH , 15 Amp Low Profile Power PC Board Relay
PCD3310T ,Pulse and DTMF diallers with redial
PCD3310T ,Pulse and DTMF diallers with redial
P89LPC920FDH-P89LPC921FDH-P89LPC922FDH-P89LPC922FN
8-bit microcontrollers with two-clock 80C51 core 2 kB/4 kB/8 kB 3 V low-power Flash with 256-byte data RAM
P89LPC920/921/9228-bit microcontrollers with two-clock 80C51 core kB/4 kB/8 kB 3 V low-power Flash with 256-byte data RAM
Rev. 06 — 21 November 2003 Product data General descriptionThe P89LPC920/921/922 are single-chip microcontrollers designed for applications
demanding high-integration, low cost solutions over a wide range of performance
requirements. The P89LPC920/921/922 is based on a high performance processor
architecture that executes instructions in two to four clocks, six times the rate of
standard 80C51 devices. Many system-level functions have been incorporated into
the P89LPC920/921/922 in order to reduce component count, board space, and
system cost.
Features
2.1 Principal features2 kB/4 kB/8 kB Flash code memory with 1 kB erasable sectors, 64-byte erasable
page size, and single byte erase. 256-byte RAM data memory. Two 16-bit counter/timers. Each timer may be configured to toggle a port output
upon timer overflow or to become a PWM output. Real-Time clock that can also be used as a system timer. Two analog comparators with selectable inputs and reference source. Enhanced UART with fractional baud rate generator, break detect, framing error
detection, automatic address detection and versatile interrupt capabilities. 400 kHz byte-wide I2 C-bus communication port. Configurable on-chip oscillator with frequency range and RC oscillator options
(selected by user programmed Flash configuration bits). The RC oscillator option
allows operation without external oscillator components. Oscillator options
support frequencies from20 kHzto the maximum operating frequencyof12 MHz.
The RC oscillator option is selectable and fine tunable. 2.4Vto 3.6V VDD operating range. I/O pins are5V tolerant (maybe pulledupor
driven to 5.5 V). 15 I/O pins minimum. Up to 18 I/O pins while using on-chip oscillator and reset
options.
2.2 Additional features 20-pin TSSOP and DIP packages. A high performance 80C51 CPU provides instruction cycle times of 167 ns to
333 ns for all instructions except multiply and divide when executing at 12 MHz.
Thisis6 times the performanceof the standard 80C51 runningat the same clock
frequency. A lower clock frequency for the same performance results in power
savings and reduced EMI.
Philips Semiconductors P89LPC920/921/922
8-bit microcontrollers with two-clock 80C51 core In-Application Programming of the Flash code memory. This allows changing the
code in a running application. Serial Flash programming allows simple in-circuit production coding. Flash
security bits prevent reading of sensitive application programs. Watchdog timer with separate on-chip oscillator, requiring no external
components. The watchdog prescaler is selectable from 8 values. Low voltage reset (Brownout detect) allows a graceful system shutdown when
power fails. May optionally be configured as an interrupt. Idle and two different Power-down reduced power modes. Improved wake-up from
Power-down mode (a low interrupt input starts execution). Typical Power-down
current is 1 μA (total Power-down with voltage comparators disabled). Active-LOW reset. On-chip power-on reset allows operation without external reset
components. A reset counter and reset glitch suppression circuitry prevent
spurious and incomplete resets. A software reset function is also available. Oscillator Fail Detect. The watchdog timer has a separate fully on-chip oscillator
allowing it to perform an oscillator fail detect function. Programmable port output configuration options: quasi-bidirectional, open drain, push-pull, input-only. Port ‘input pattern match’ detect. Port0 may generatean interrupt when the value
of the pins match or do not match a programmable pattern. LED drive capability (20 mA) on all port pins. A maximum limit is specified for the
entire chip. Controlled slew rate port outputs to reduce EMI. Outputs have approximately ns minimum ramp times. Only power and ground connections are required to operate the
P89LPC920/921/922 when internal reset option is selected. Four interrupt priority levels. Eight keypad interrupt inputs, plus two additional external interrupt inputs. Second data pointer. Schmitt trigger port inputs. Emulation support.
Philips Semiconductors P89LPC920/921/922
8-bit microcontrollers with two-clock 80C51 core Ordering information
3.1 Ordering options
Table 1: Ordering informationP89LPC920FDH TSSOP20 plastic thin shrink small outline package; leads; body width 4.4 mm
SOT360-1
P89LPC921FDH TSSOP20 plastic thin shrink small outline package; leads; body width 4.4 mm
SOT360-1
P89LPC922FDH TSSOP20 plastic thin shrink small outline package; leads; body width 4.4 mm
SOT360-1
P89LPC922FN DIP20 plastic dual in-line package; 20 leads (300 mil) SOT146-1
Table 2: Part optionsP89LPC920FDH 2kB −40 °Cto+85°C 0to12 MHz
P89LPC921FDH 4kB −40 °Cto+85°C 0to12 MHz
P89LPC922FDH 8kB −40 °Cto+85°C 0to12 MHz
P89LPC922FN 8kB −40 °Cto+85°C 0to12 MHz
Philips Semiconductors P89LPC920/921/922
8-bit microcontrollers with two-clock 80C51 core Block diagram
Philips Semiconductors P89LPC920/921/922
8-bit microcontrollers with two-clock 80C51 core Pinning information
5.1 Pinning
Philips Semiconductors P89LPC920/921/922
8-bit microcontrollers with two-clock 80C51 core
5.2 Pin description
Table 3: Pin descriptionP0.0 - P0.7 1, 20, 19,
18, 17,16,
14, 13
I/O
Port0: Port 0 is an 8-bit I/O port with a user-configurable output type. During reset
Port 0 latches are configured in the input only mode with the internal pull-up disabled.
The operationof Port0 pinsas inputs and outputs depends upon the port configuration
selected. Each port pin is configured independently. Refer to Section 8.12.1 “Port
configurations” and Table 8 “DC electrical characteristics” for details.
The Keypad Interrupt feature operates with Port 0 pins.
All pins have Schmitt triggered inputs.
Port 0 also provides various special functions as described below: I/O
P0.0 — Port 0 bit0.
CMP2 — Comparator 2 output.
KBI0 — Keyboard input 0. I/O
P0.1 — Port 0 bit1.
CIN2B — Comparator 2 positive input B.
KBI1 — Keyboard input 1. I/O
P0.2 — Port 0 bit2.
CIN2A — Comparator 2 positive input A.
KBI2 — Keyboard input 2. I/O
P0.3 — Port 0 bit3.
CIN1B — Comparator 1 positive input B.
KBI3 — Keyboard input 3. I/O
P0.4 — Port 0 bit4.
CIN1A — Comparator 1 positive input A.
KBI4 — Keyboard input 4. I/O
P0.5 — Port 0 bit5.
CMPREF — Comparator reference (negative) input.
KBI5 — Keyboard input 5. I/O
P0.6 — Port 0 bit6.
CMP1 — Comparator 1 output.
KBI6 — Keyboard input 6. I/O
P0.7 — Port 0 bit7.
I/O
T1 — Timer/counter 1 external count input or overflow output.
KBI7 — Keyboard input 7.
Philips Semiconductors P89LPC920/921/922
8-bit microcontrollers with two-clock 80C51 coreP1.0 - P1.7 12, 11,10,
9, 8, 4, 3,
I/O,I[1]
Port 1: Port 1 is an 8-bit I/O port with a user-configurable output type, except for three
pins as noted below. During reset Port 1 latches are configured in the input only mode
withthe internal pull-up disabled. The operationof the configurable Port1 pinsas inputs
and outputs depends upon the port configuration selected. Each of the configurable
port pins are programmed independently. Refer to Section 8.12.1 “Port configurations”
and Table 8 “DC electrical characteristics” for details. P1.2 - P1.3 are open drain when
used as outputs. P1.5 is input only.
All pins have Schmitt triggered inputs.
Port 1 also provides various special functions as described below: I/O
P1.0 — Port 1 bit0.
TXD — Transmitter output for the serial port. I/O
P1.1 — Port 1 bit1.
RXD — Receiver input for the serial port. I/O
P1.2 — Port 1 bit 2 (open-drain when used as output).
I/O
T0 — Timer/counter0 external count inputor overflow output (open-drain when usedas
output).
I/O
SCL —I2 C serial clock input/output. I/O
P1.3 — Port 1 bit 3 (open-drain when used as output).
INT0 — External interrupt 0 input.
I/O
SDA —I2 C serial data input/output. I/O
P1.4 — Port 1 bit4.
INT1 — External interrupt 1 input.
P1.5 — Port 1 bit 5 (input only).
RST — External Reset input (if selected via FLASH configuration). A LOW on this pin
resets the microcontroller, causing I/O ports and peripherals to take on their default
states, and the processor begins execution at address0. I/O
P1.6 — Port 1 bit6. I/O
P1.7 — Port 1 bit7.
Table 3: Pin description…continued
Philips Semiconductors P89LPC920/921/922
8-bit microcontrollers with two-clock 80C51 core[1] Input/Output for P1.0-P1.4, P1.6, P1.7. Input for P1.5.
Logic symbolP3.0 - P3.1 7, 6 I/O
Port 3: Port 3 is an 2-bit I/O port with a user-configurable output type. During reset
Port 3 latches are configured in the input only mode with the internal pull-up disabled.
The operationof Port3 pinsas inputs and outputs depends upon the port configuration
selected. Each port pin is configured independently. Refer to Section 8.12.1 “Port
configurations” and Table 8 “DC electrical characteristics” for details.
All pins have Schmitt triggered inputs.
Port 3 also provides various special functions as described below: I/O
P3.0 — Port 3 bit0.
XTAL2 — Output from the oscillator amplifier (when a crystal oscillator option is
selected via the FLASH configuration.
CLKOUT — CPU clock divided by 2 when enabled via SFR bit (ENCLK - TRIM.6). It
can be used if the CPU clock is the internal RC oscillator, watchdog oscillator or
external clock input, except when XTAL1/XTAL2 are used to generate clock source for
the real time clock/system timer. I/O
P3.1 — Port 3 bit1.
XTAL1 — Input to the oscillator circuit and internal clock generator circuits (when
selected via the FLASH configuration). It can be a port pin if internal RC oscillator or
watchdog oscillatoris usedasthe CPU clock source,
andif XTAL1/XTAL2 arenot used
to generate the clock for the real time clock/system timer.
VSS 5I
Ground: 0 V reference.
VDD 15 I
Power Supply: This is the power supply voltage for normal operation as well as Idleand Power Down modes.
Table 3: Pin description…continued
Philips Semiconductors P89LPC920/921/922
8-bit microcontrollers with two-clock 80C51 core Special function registers
Remark: Special Function Registers (SFRs) accesses are restricted in the following
ways:
User must
not attempt to access any SFR locations not defined. Accesses to any defined SFR locations must be strictly for the functions for the
SFRs.
SFR bits labeled ‘-’, ‘0’ or ‘1’ can
only be written and read as follows:‘-’ Unless otherwise specified,
mustbe written with ‘0’, but can return any value
when read (evenifit was written with ‘0’).Itisa reservedbit and maybe usedin
future derivatives.
‘0’
must be written with ‘0’, and will return a ‘0’ when read.‘1’
must be written with ‘1’, and will return a ‘1’ when read.
xxxxxxxxxxxxxxxxxxxxx xxxxxxxxxxxxxxxxxxxxxxxxxx xxxxxxx x x x xxxxxxxxxxxxxxxxxxxxxxxxxxxxxx xxxxxxxxxxxxxxxxxxx xx xxxxxxx xxxxxxxxxxxxxxxxxxxxxxxxxxx xxxxxxxxxxxxxxxxxxx xxxxxx xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx xxxxxxxxxxxx x xxxxxxxxxxxxxxxxxxxxxx xxxxxxxxxxxxxxxxxxxxxxxxxxxxxx xxxxx xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx xxxxxxxxxxxxxxxxxxxx xxx
Philips Semiconductors P89LPC920/921/922
8-bit microcontrollers with two-clock 80C51 core
le 4:
Special function register
xxxxxxxxxxxxxxxxxxxxx xxxxxxxxxxxxxxxxxxxxxxxxxx xxxxxxx x x x xxxxxxxxxxxxxxxxxxxxxxxxxxxxxx xxxxxxxxxxxxxxxxxxx xx xxxxxxx xxxxxxxxxxxxxxxxxxxxxxxxxxx xxxxxxxxxxxxxxxxxxx xxxxxx xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx xxxxxxxxxxxx x xxxxxxxxxxxxxxxxxxxxxx xxxxxxxxxxxxxxxxxxxxxxxxxxxxxx xxxxx xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx xxxxxxxxxxxxxxxxxxxx xxx
Philips Semiconductors P89LPC920/921/922
8-bit microcontrollers with two-clock 80C51 core
le 4:
Special function register
…contin
ued
xxxxxxxxxxxxxxxxxxxxx xxxxxxxxxxxxxxxxxxxxxxxxxx xxxxxxx x x x xxxxxxxxxxxxxxxxxxxxxxxxxxxxxx xxxxxxxxxxxxxxxxxxx xx xxxxxxx xxxxxxxxxxxxxxxxxxxxxxxxxxx xxxxxxxxxxxxxxxxxxx xxxxxx xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx xxxxxxxxxxxx x xxxxxxxxxxxxxxxxxxxxxx xxxxxxxxxxxxxxxxxxxxxxxxxxxxxx xxxxx xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx xxxxxxxxxxxxxxxxxxxx xxx
Philips Semiconductors P89LPC920/921/922
8-bit microcontrollers with two-clock 80C51 core
le 4:
Special function register
…contin
ued
xxxxxxxxxxxxxxxxxxxxx xxxxxxxxxxxxxxxxxxxxxxxxxx xxxxxxx x x x xxxxxxxxxxxxxxxxxxxxxxxxxxxxxx xxxxxxxxxxxxxxxxxxx xx xxxxxxx xxxxxxxxxxxxxxxxxxxxxxxxxxx xxxxxxxxxxxxxxxxxxx xxxxxx xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx xxxxxxxxxxxx x xxxxxxxxxxxxxxxxxxxxxx xxxxxxxxxxxxxxxxxxxxxxxxxxxxxx xxxxx xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx xxxxxxxxxxxxxxxxxxxx xxx
Philips Semiconductors P89LPC920/921/922
8-bit microcontrollers with two-clock 80C51 core
All por
ts are in input only (high impedance) state after po
er-up
BRGR1 and BRGR0 m
ust only be wr
itten if BRGEN in BRGCON SFR is ‘0’. If an
y are wr
itten while BRGEN
1, the result is unpredic
tab
The RSTSRC register reflects the cause of the P89LPC920/921/922 reset. Upon a po
er-up reset, all reset source flags are clear
ed e
xcept POF and BOF; the po
er-on reset
alue is xx110000.
After
reset,
the
alue
111001x1,
i.e
PRE2-PRE0
are
all
‘1’,
WDR
and
WDCLK
WDT
bit
‘1’
after
atchdog
reset
and
‘0’
after
er-on
reset.
Other
resets
will
not aff
ect WDT
On po
er-on reset, the TRIM SFR is initializ
ed with a f
actor
y preprog
rammed v
alue
. Other resets will not cause initializatio
n of the TRIM register
The only reset source that aff
ects these SFRs is po
er-on reset.
le 4:
Special function register
…contin
ued
Philips Semiconductors P89LPC920/921/922
8-bit microcontrollers with two-clock 80C51 core Functional description
Remark: Please refer to the P89LPC920/921/922 User’s Manual for a more detailed
functional description.
8.1 Enhanced CPU
The P89LPC920/921/922 uses an enhanced 80C51 CPU which runs at 6 times the
speedof standard 80C51 devices.A machine cycle consistsof two CPU clock cycles,
and most instructions execute in one or two machine cycles.
8.2 Clocks
8.2.1 Clock definitions
The P89LPC920/921/922 device has several internal clocks as defined below:
OSCCLK — Input to the DIVM clock divider. OSCCLK is selected from one of four
clock sources (see Figure5) and can alsobe optionally dividedtoa slower frequency
(see Section 8.7 “CPU Clock (CCLK) modification: DIVM register”).
Note: fOSC is defined as the OSCCLK frequency.
CCLK — CPU clock; output of the clock divider. There are two CCLK cycles per
machine cycle, and most instructions are executedin oneto two machine cycles (two
or four CCLK cycles).
RCCLK — The internal 7.373 MHz RC oscillator output.
PCLK — Clock for the various peripheral devices and is CCLK/2
8.2.2 CPU clock (OSCCLK)
The P89LPC920/921/922 provides several user-selectable oscillator options in
generating the CPU clock. This allows optimization for a range of needs from high
precision to lowest possible cost. These options are configured when the FLASH is
programmed and includean on-chip watchdog oscillator,an on-chip RC oscillator,an
oscillator using an external crystal, or an external clock source. The crystal oscillator
can be optimized for low, medium, or high frequency crystals covering a range from kHz to 12 MHz.
8.2.3 Low speed oscillator option
This option supports an external crystal in the range of 20 kHz to 100 kHz. Ceramic
resonators are also supported in this configuration.
8.2.4 Medium speed oscillator option
This option supports an external crystal in the range of 100 kHz to 4 MHz. Ceramic
resonators are also supported in this configuration.
8.2.5 High speed oscillator option
This option supports an external crystal in the range of 4 MHz to 12 MHz. Ceramic
resonators are also supported in this configuration.
Philips Semiconductors P89LPC920/921/922
8-bit microcontrollers with two-clock 80C51 core
8.2.6 Clock output
The P89LPC920/921/922 supports a user-selectable clock output function on the
XTAL2/CLKOUT pin when crystal oscillatoris not being used. This condition occursif
another clock source has been selected (on-chip RC oscillator, watchdog oscillator,
external clock input on X1) and if the Real-Time clock is not using the crystal
oscillator as its clock source. This allows external devices to synchronize to the
P89LPC920/921/922. This output is enabled by the ENCLK bit in the TRIM register.
The frequency of this clock output is1 ⁄2 that of the CCLK. If the clock output is not
needed in Idle mode, it may be turned off prior to entering Idle, saving additional
power.
8.3 On-chip RC oscillator option
The P89LPC920/921/922 has a 6-bit TRIM register that can be used to tune the
frequency of the RC oscillator. During reset, the TRIM value is initialized to a factory
pre-programmed value to adjust the oscillator frequency to 7.373 MHz, ±1% at room
temperature. End-user applications can writeto the Trim registerto adjust the on-chip
RC oscillator to other frequencies.
8.4 Watchdog oscillator option
The watchdog has a separate oscillator which has a frequency of 400 kHz. This
oscillator can be used to save power when a high clock frequency is not needed.
8.5 External clock input option
In this configuration, the processor clock is derived from an external source driving
the XTAL1/P3.1 pin. The rate may be from 0 Hz up to 12 MHz. The XTAL2/P3.0 pin
may be used as a standard port pin or a clock output.
Philips Semiconductors P89LPC920/921/922
8-bit microcontrollers with two-clock 80C51 core
8.6 CPU Clock (CCLK) wake-up delay
The P89LPC920/921/922 has an internal wake-up timer that delays the clock until it
stabilizes depending to the clock source used. If the clock source is any of the three
crystal selections (low, medium and high frequencies) the delay is 992 OSCCLK
cycles plus 60to 100 μs. If the clock source is either the internal RC oscillator,
watchdog oscillator, or external clock, the delay is 224 OSCCLK cycles plusto 100 μs.
8.7 CPU Clock (CCLK) modification: DIVM register
The OSCCLK frequency can be divided down up to 510 times by configuring a
dividing register, DIVM, to generate CCLK. This feature makes it possible to
temporarily run the CPUata lower rate, reducing power consumption.By dividing the
clock, the CPU can retain the ability to respond to events that would not exit Idle
modeby executingits normal programata lower rate. This can also allow bypassing
the oscillator start-up time in cases where Power-down mode would otherwise be
used. The value of DIVM may be changed by the program at any time without
interrupting code execution.
8.8 Low power select
The P89LPC920/921/922 is designed to run at 12 MHz (CCLK) maximum. However,
if CCLK is 8 MHz or slower, the CLKLP SFR bit (AUXR1.7) can be set to ‘1’ to lower
the power consumption further. On any reset, CLKLP is ‘0’ allowing highest
performance access. Thisbit can thenbe setin softwareif CCLKis runningat8 MHz
or slower.
8.9 Memory organization
The various P89LPC920/921/922 memory spaces are as follows: DATA
128 bytesof internal data memory space (00h:7Fh) accessed via director indirect
addressing, using instruction other than MOVX and MOVC.Allor partof the Stack
may be in this area. IDATA
Indirect Data. 256 bytes of internal data memory space (00h:FFh) accessed via
indirect addressing using instructions other than MOVX and MOVC. All or part of
the Stack maybein this area. This area includes the DATA area and the 128 bytes
immediately above it. SFR
Special Function Registers. Selected CPU registers and peripheral control and
status registers, accessible only via direct addressing. CODEkBof Code memory space, accessedas partof program execution and via the
MOVC instruction. The P89LPC920/921/922 has 2 kB/4 kB/8 kB of on-chip Code
memory.
Philips Semiconductors P89LPC920/921/922
8-bit microcontrollers with two-clock 80C51 core
8.10 Data RAM arrangement
The 256 bytes of on-chip RAM are organized as shown in Table5.
8.11 Interrupts
The P89LPC920/921/922 uses a four priority level interrupt structure. This allows
great flexibility in controlling the handling of the many interrupt sources. The
P89LPC920/921/922 supports 12 interrupt sources: external interrupts 0 and 1,
timers 0 and 1, serial port Tx, serial port Rx, combined serial port Rx/Tx, brownout
detect, watchdog/real-time clock, I2 C, keyboard, and comparators 1 and 2.
Each interrupt source canbe individually enabledor disabledby settingor clearinga
bit in the interrupt enable registers IEN0 or IEN1. The IEN0 register also contains a
global disable bit, EA, which disables all interrupts.
Each interrupt source canbe individually programmedto oneof four priority levelsby
setting or clearing bits in the interrupt priority registers IP0, IP0H, IP1, and IP1H. An
interrupt service routine in progress can be interrupted by a higher priority interrupt,
but notby another interruptof the sameor lower priority. The highest priority interrupt
service cannot be interrupted by any other interrupt source. If two requests of
different priority levels are pendingat the startofan instruction, the requestof higher
priority level is serviced.
If requests of the same priority level are pending at the start of an instruction, an
internal polling sequence determines which request is serviced. This is called the
arbitration ranking. Note that the arbitration ranking is only used to resolve pending
requests of the same priority level.
8.11.1 External interrupt inputs
The P89LPC920/921/922 has two external interrupt inputs as well as the Keypad
Interrupt function. The two interrupt inputs are identical to those present on the
standard 80C51 microcontrollers.
These external interrupts canbe programmedtobe level-triggeredor edge-triggered
by setting or clearing bit IT1 or IT0 in Register TCON.
In edge-triggered mode if successive samples of the INTn pin show a HIGH in one
cycle and a LOW in the next cycle, the interrupt request flag IEn in TCON is set,
causing an interrupt request.
If an external interrupt is enabled when the P89LPC920/921/922 is put into
Power-down or Idle mode, the interrupt will cause the processor to wake-up and
resume operation. Refer to Section 8.14 “Power reduction modes” for details.
Table 5: On-chip data memory usages
DATA Memory that can be addressed directly and indirectly 128
IDATA Memory that can be addressed indirectly 256
Philips Semiconductors P89LPC920/921/922
8-bit microcontrollers with two-clock 80C51 core
8.12 I/O ports
The P89LPC920/921/922 has three I/O ports: Port 0, Port 1, and Port 3. Ports 0 and
1 are 8-bit ports, and Port 3 is a 2-bit port. The exact number of I/O pins available
depend upon the clock and reset options chosen, as shown in Table6.
8.12.1 Port configurations
All but three I/O port pinson the P89LPC920/921/922 maybe configuredby software
to one of four types on a bit-by-bit basis. These are: quasi-bidirectional (standard
80C51 port outputs), push-pull, open drain, and input-only. Two configuration
registers for each port select the output type for each port pin.
P1.5 (RST) can only be an input and cannot be configured.
P1.2 (SCL/T0) and P1.3 (SDA/INT0) may onlybe configuredtobe either input-onlyor
open-drain.
Table 6: Number of I/O pins available
On-chip oscillator or watchdog oscillator No external reset (except during power-up) 18
External RST pin supported 17
External clock input No external reset (except during power-up) 17
External RST pin supported 16
Low/medium/high speed oscillator
(external crystal or resonator)
No external reset (except during power-up) 16
External RST pin supported 15
Philips Semiconductors P89LPC920/921/922
8-bit microcontrollers with two-clock 80C51 core
8.12.2 Quasi-bidirectional output configuration
Quasi-bidirectional output type can be used as both an input and output without the
need to reconfigure the port. This is possible because when the port outputs a logic
HIGH, it is weakly driven, allowing an external device to pull the pin LOW. When the
pin is driven LOW, it is driven strongly and able to sink a fairly large current. These
features are somewhat similar to an open-drain output except that there are three
pull-up transistors in the quasi-bidirectional output that serve different purposes.
The P89LPC920/921/922 is a 3 V device, but the pins are 5 V-tolerant. In
quasi-bidirectional mode, if a user applies 5 V on the pin, there will be a current
flowing from the pin to VDD, causing extra power consumption. Therefore, applying V in quasi-bidirectional mode is discouraged.
A quasi-bidirectional port pin has a Schmitt-triggered input that also has a glitch
suppression circuit.
8.12.3 Open-drain output configuration
The open-drain output configuration turns off all pull-ups and only drives the
pull-down transistor of the port driver when the port latch contains a logic ‘0’. To be
used as a logic output, a port configured in this manner must have an external
pull-up, typically a resistor tied to VDD.
An open-drain port pin has a Schmitt-triggered input that also has a glitch
suppression circuit.
8.12.4 Input-only configuration
The input-only port configuration hasno output drivers.Itisa Schmitt-triggered input
that also has a glitch suppression circuit.
8.12.5 Push-pull output configuration
The push-pull output configuration has the same pull-down structure as both the
open-drain and the quasi-bidirectional output modes, but provides a continuous
strong pull-up when the port latch contains a logic ‘1’. The push-pull mode may be
used when more source current is needed from a port output. A push-pull port pin
has a Schmitt-triggered input that also has a glitch suppression circuit.
8.12.6 Port 0 analog functions
The P89LPC920/921/922 incorporates two Analog Comparators. In order to give the
best analog function performance and to minimize power consumption, pins that are
being used for analog functions must have the digital outputs and digital inputs
disabled.
Digital outputs are disabled by putting the port output into the Input-Only (high
impedance) mode as described in Section 8.12.4.
Digital inputs on Port 0 may be disabled through the use of the PT0AD register,
bits 1:5. On any reset, PT0AD1:5 defaults to ‘0’s to enable digital functions.
Philips Semiconductors P89LPC920/921/922
8-bit microcontrollers with two-clock 80C51 core
8.12.7 Additional port features
After power-up, all pins are in Input-Only mode. Please note that this is different
from the LPC76x series of devices. After power-up, all I/O pins except P1.5, may be configured by software. Pin P1.5is input only. Pins P1.2 and P1.3 and are configurablefor either input-only
or open-drain.
Every output on the P89LPC920/921/922 has been designed to sink typical LED
drive current. However, there is a maximum total output current for all ports which
must not be exceeded. Please refer to Table 8 “DC electrical characteristics” for
detailed specifications.
All ports pins that can function as an output have slew rate controlled outputs to limit
noise generated by quickly switching output signals. The slew rate is factory-set to
approximately 10 ns rise and fall times.
8.13 Power monitoring functions
The P89LPC920/921/922 incorporates power monitoring functions designed to
prevent incorrect operation during initial power-up and power lossor reduction during
operation. This is accomplished with two hardware functions: Power-on Detect and
Brownout detect.
8.13.1 Brownout detection
The Brownout detect function determines if the power supply voltage drops below a
certain level. The default operation is for a Brownout detection to cause a processor
reset, however it may alternatively be configured to generate an interrupt.
Brownout detection may be enabled or disabled in software. Brownout detectionis enabled, the operating voltage rangefor VDDis 2.7Vto 3.6V,
and the brownout condition occurs when VDD falls below the brownout trip voltage,
VBO (see Table 8 “DC electrical characteristics”), and is negated when VDD rises
above VBO. If brownout detection is disabled, the operating voltage range for VDD is
2.4Vto 3.6 V. If the P89LPC920/921/922 device is to operate with a power supply
that can be below 2.7 V, BOE should be left in the unprogrammed state so that the
device can operate at 2.4 V, otherwise continuous brownout reset may prevent the
device from operating.
For correct activation of Brownout detect, the VDD rise and fall times must be
observed. Please see Table 8 “DC electrical characteristics” for specifications.
8.13.2 Power-on detection
The Power-on Detect hasa function similarto the Brownout detect, butis designedto
work as power comes up initially, before the power supply voltage reaches a level
where Brownout detect can work. The POF flag in the RSTSRC register is set to
indicate an initial power-up condition. The POF flag will remain set until cleared by
software.
Philips Semiconductors P89LPC920/921/922
8-bit microcontrollers with two-clock 80C51 core
8.14 Power reduction modes
The P89LPC920/921/922 supports three different power reduction modes. These
modes are Idle mode, Power-down mode, and total Power-down mode.
8.14.1 Idle mode
Idle mode leaves peripherals runningin orderto allow themto activate the processor
when an interrupt is generated. Any enabled interrupt source or reset may terminate
Idle mode.
8.14.2 Power-down mode
The Power-down mode stops the oscillator in order to minimize power consumption.
The P89LPC920/921/922 exits Power-down mode via any reset,or certain interrupts.
In Power-down mode, the power supply voltage may be reduced to the RAM
keep-alive voltage VRAM. This retains the RAM contents at the point where
Power-down mode was entered. SFR contents are not guaranteed after VDD has
been lowered to VRAM, therefore it is highly recommended to wake up the processor
via reset in this case. VDD must be raised to within the operating range before the
Power-down mode is exited.
Some chip functions continue to operate and draw power during Power-down mode,
increasing the total power used during Power-down. These include: Brownout detect,
Watchdog Timer, Comparators (note that Comparators can be powered-down
separately), and Real-Time Clock (RTC)/System Timer. The internal RC oscillator is
disabled unless both the RC oscillator has been selected as the system clock AND
the RTC is enabled.
8.14.3 Total Power-down mode
This is the same as Power-down mode except that the brownout detection circuitry
and the voltage comparators are also disabled to conserve additional power. The
internal RC oscillator is disabled unless both the RC oscillator has been selected as
the system clock and the RTCis enabled.If the internal RC oscillatoris usedto clock
the RTC during Power-down, there will be high power consumption. Please use an
external low frequency clock to achieve low power with the Real-Time Clock running
during Power-down.
8.15 Reset
The P1.5/RST pin can function as either an active-LOW reset input or as a digital
input, P1.5. The RPE (Reset Pin Enable) bit in UCFG1, when set to ‘1’, enables the
external reset input function on P1.5. When cleared, P1.5 may be used as an input
pin.
Remark: During a power-up sequence, the RPE selection is overridden and this pin
will always function as a reset input. An external circuit connected to this pin
should not hold this pin LOW duringa power-on sequenceas this will keep the
device in reset. After power-up this input will function either as an external reset
input or as a digital input as defined by the RPE bit. Only a power-up reset will
temporarily override the selection defined by RPE bit. Other sources of reset will not
override the RPE bit.
Philips Semiconductors P89LPC920/921/922
8-bit microcontrollers with two-clock 80C51 core
Remark: Duringa power cycle, VDD must fall below VPOR (see Table8 “DC electrical
characteristics”on page 35) before poweris reapplied,in orderto ensurea power-on
reset.
Reset can be triggered from the following sources: External reset pin (during power-up or if user configured via UCFG1); Power-on detect; Brownout detect; Watchdog Timer; Software reset; UART break character detect reset.
For every reset source, there is a flag in the Reset Register, RSTSRC. The user can
read this register to determine the most recent reset source. These flag bits can be
cleared in software by writing a ‘0’ to the corresponding bit. More than one flag bit
may be set: During a power-on reset, both POF and BOF are set but the other flag bits are
cleared. For any other reset, previously set flag bits that have not been cleared will remain
set.
8.15.1 Reset vector
Following reset, the P89LPC920/921/922 will fetch instructions from either address
0000h or the Boot address. The Boot address is formed by using the Boot Vector as
the high byte of the address and the low byte of the address= 00h.
The Boot address willbe usedifa UART break reset occurs,or the non-volatile Boot
Status bit (BOOTSTAT.0)= 1, or the device is forced into ISP mode during power-on
(see P89LPC920/921/922 User’s Manual). Otherwise, instructions will be fetched
from address 0000H.
8.16 Timers/counters 0 and 1
The P89LPC920/921/922 has two general purpose counter/timers which are upward
compatible with the standard 80C51 Timer 0 and Timer 1. Both can be configured to
operate either as timers or event counter. An option to automatically toggle the T0
and/or T1 pins upon timer overflow has been added.
In the ‘Timer’ function, the register is incremented every machine cycle. the ‘Counter’ function, the registeris incrementedin responsetoa 1-to-0 transition
at its corresponding external input pin, T0 or T1. In this function, the external input is
sampled once during every machine cycle.
Timer0 and Timer1 have five operating modes (modes0,1,2,3 and 6). Modes0,1,
2 and 6 are the same for both Timers/Counters. Mode 3 is different.
Philips Semiconductors P89LPC920/921/922
8-bit microcontrollers with two-clock 80C51 core
8.16.1 Mode0
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. In this mode, the Timer register is configured
as a 13-bit register. Mode 0 operation is the same for Timer 0 and Timer1.
8.16.2 Mode1
Mode 1 is the same as Mode 0, except that all 16 bits of the timer register are used.
8.16.3 Mode2
Mode 2 configures the Timer register as an 8-bit Counter with automatic reload.
Mode 2 operation is the same for Timer 0 and Timer1.
8.16.4 Mode3
When Timer 1 is in Mode 3 it is stopped. Timer 0 in Mode 3 forms two separate 8-bit
counters and is provided for applications that require an extra 8-bit timer. When
Timer 1 is in Mode 3 it can still be used by the serial port as a baud rate generator.
8.16.5 Mode6
In this mode, the corresponding timer can be changed to a PWM with a full period of
256 timer clocks.
8.16.6 Timer overflow toggle output
Timers 0 and 1 can be configured to automatically toggle a port output whenever a
timer overflow occurs. The same device pins that are used for the T0 and T1 count
inputs are also used for the timer toggle outputs. The port outputs will be a logic1
prior to the first timer overflow when this mode is turned on.
8.17 Real-Time clock/system timer
The P89LPC920/921/922 hasa simple Real-Time clock that allowsa userto continue
running an accurate timer while the rest of the device is powered-down. The
Real-Time clock can be a wake-up or an interrupt source. The Real-Time clock is a
23-bit down counter comprised of a 7-bit prescaler and a 16-bit loadable down
counter. When it reaches all ‘0’s, the counter will be reloaded again and the RTCF
flag willbe set. The clock sourcefor this counter canbe either the CPU clock (CCLK) the XTAL oscillator, provided that the XTAL oscillatoris not being usedas the CPU
clock.If the XTAL oscillatoris usedas the CPU clock, then the RTC will use CCLKas
its clock source. Only power-on reset will reset the Real-Time clock and its
associated SFRs to the default state.
8.18 UART
The P89LPC920/921/922 has an enhanced UART that is compatible with the
conventional 80C51 UART except that Timer 2 overflow cannot be used as a baud
rate source. The P89LPC920/921/922 does include an independent Baud Rate
Generator. The baud rate canbe selected from the oscillator (dividedbya constant),
Timer 1 overflow, or the independent Baud Rate Generator. In addition to the baud
rate generation, enhancements over the standard 80C51 UART include Framing
Error detection, automatic address recognition, selectable double buffering and
several interrupt options.The UART can be operated in 4 modes: shift register, 8-bit
UART, 9-bit UART, and CPU clock/32 or CPU clock/16.
