P89LPC931A1FDH,512 NXP Semiconductors, P89LPC931A1FDH,512 Datasheet - Page 36

• Manufacturer Part Number: P89LPC931A1FDH,512
• Description: IC 80C51 MCU FLASH 8K 28-TSSOP
• Manufacturer: NXP Semiconductors
• Series: LPC900r

Specifications of P89LPC931A1FDH,512

• Program Memory Type: FLASH
• Program Memory Size: 8KB (8K x 8)
• Package / Case: 28-TSSOP
• Core Processor: 8051
• Core Size: 8-Bit
• Speed: 18MHz
• Connectivity: I²C, SPI, UART/USART
• Peripherals: Brown-out Detect/Reset, POR, PWM, WDT
• Number Of I /o: 26
• Ram Size: 256 x 8
• Voltage - Supply (vcc/vdd): 2.4 V ~ 3.6 V
• Oscillator Type: Internal
• Operating Temperature: -40°C ~ 85°C
• Processor Series: P89LPC
• Core: 80C51
• Data Bus Width: 8 bit
• Data Ram Size: 256 B
• Interface Type: I2C, SPI, UART
• Maximum Clock Frequency: 18 MHz
• Number Of Programmable I/os: 23
• Number Of Timers: 3
• Operating Supply Voltage: 2.4 V to 3.6 V
• Maximum Operating Temperature: + 85 C
• Mounting Style: SMD/SMT
• 3rd Party Development Tools: PK51, CA51, A51, ULINK2
• Minimum Operating Temperature: - 40 C
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• For Use With: 568-1758 - BOARD EVAL FOR LPC93X MCU FAMILY
• Eeprom Size: -
• Data Converters: -
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant
• Other names: 935288634512

NXP Semiconductors
P89LPC9301_931A1
Product data sheet
7.26 KBI
7.27 Watchdog timer
The Keypad Interrupt function (KBI) is intended primarily to allow a single interrupt to be
generated when Port 0 is equal to or not equal to a certain pattern. This function can be
used for bus address recognition or keypad recognition. The user can configure the port
via SFRs for different tasks.
The Keypad Interrupt Mask Register (KBMASK) is used to define which input pins
connected to Port 0 can trigger the interrupt. The Keypad Pattern Register (KBPATN) is
used to define a pattern that is compared to the value of Port 0. The Keypad Interrupt Flag
(KBIF) in the Keypad Interrupt Control Register (KBCON) is set when the condition is
matched while the Keypad Interrupt function is active. An interrupt will be generated if
enabled. The PATN_SEL bit in the Keypad Interrupt Control Register (KBCON) is used to
define equal or not-equal for the comparison.
In order to use the Keypad Interrupt as an original KBI function like in P87LPC76x series,
the user needs to set KBPATN = 0FFH and PATN_SEL = 1 (not equal), then any key
connected to Port 0 which is enabled by the KBMASK register will cause the hardware to
set KBIF and generate an interrupt if it has been enabled. The interrupt may be used to
wake-up the CPU from Idle or Power-down modes. This feature is particularly useful in
handheld, battery-powered systems that need to carefully manage power consumption
yet also need to be convenient to use.
In order to set the flag and cause an interrupt, the pattern on Port 0 must be held longer
than six CCLKs.
The watchdog timer causes a system reset when it underflows as a result of a failure to
feed the timer prior to the timer reaching its terminal count. It consists of a programmable
12-bit prescaler, and an 8-bit down counter. The down counter is decremented by a tap
taken from the prescaler. The clock source for the prescaler can be the PCLK, the nominal
400 kHz watchdog oscillator or low speed crystal oscillator. The watchdog timer can only
be reset by a power-on reset. When the watchdog feature is disabled, it can be used as
an interval timer and may generate an interrupt.
Watchdog mode. Feeding the watchdog requires a two-byte sequence. If PCLK is
selected as the watchdog clock and the CPU is powered down, the watchdog is disabled.
The watchdog timer has a time-out period that ranges from a few s to a few seconds.
Please refer to the P89LPC9301/931A1 User manual for more details.
All information provided in this document is subject to legal disclaimers.
Rev. 2 — 29 November 2010
8-bit microcontroller with accelerated two-clock 80C51 core
P89LPC9301/931A1
Figure 14
shows the watchdog timer in
© NXP B.V. 2010. All rights reserved.
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