AT89C5132 Atmel Corporation, AT89C5132 Datasheet - Page 37

• Manufacturer Part Number: AT89C5132
• Manufacturer: Atmel Corporation

Specifications of AT89C5132

• Flash (kbytes): 64 Kbytes
• Max. Operating Frequency: 20 MHz
• Cpu: 8051-12C
• Max I/o Pins: 44
• Usb Transceiver: 1
• Usb Speed: Full Speed
• Usb Interface: Device
• Spi: 1
• Uart: 1
• Adc Channels: 2
• Adc Resolution (bits): 10
• Adc Speed (ksps): 22.7
• Sram (kbytes): 2.25
• Self Program Memory: API
• Operating Voltage (vcc): 2.7 to 3.6
• Timers: 2
• Isp: UART/USB
• Watchdog: Yes

10.2
10.2.1
10.2.2
10.2.3
4173E–USB–09/07
External Interrupts
INT1:0 Inputs
KIN3:0 Inputs
Input Sampling
External interrupts INT0 and INT1 (INTn, n = 0 or 1) pins may each be programmed to be level-
triggered or edge-triggered, dependent upon bits IT0 and IT1 (ITn, n = 0 or 1) in TCON register
as shown in Figure 10-2. If ITn = 0, INTn is triggered by a low level at the pin. If ITn = 1, INTn is
negative-edge triggered. External interrupts are enabled with bits EX0 and EX1 (EXn, n = 0 or 1)
in IEN0. Events on INTn set the interrupt request flag IEn in TCON register. If the interrupt is
edge-triggered, the request flag is cleared by hardware when vectoring to the interrupt service
routine. If the interrupt is level-triggered, the interrupt service routine must clear the request flag
and the interrupt must be deasserted before the end of the interrupt service routine.
INT0 and INT1 inputs provide both the capability to exit from Power-down mode on low level sig-
nals as detailed in Section “Exiting Power-down Mode”, page 47.
Figure 10-2. INT1:0 Input Circuitry
External interrupts KIN0 to KIN3 provide the capability to connect a matrix keyboard. For
detailed information on these inputs, refer to Section “Keyboard Interface”, page 152.
External interrupt pins (INT1:0 and KIN3:0) are sampled once per peripheral cycle (6 peripheral
clock periods) (see Figure 10-3). A level-triggered interrupt pin held low or high for more than 6
peripheral clock periods (12 oscillator in standard mode or 6 oscillator clock periods in X2 mode)
guarantees detection. Edge-triggered external interrupts must hold the request pin low for at
least 6 peripheral clock periods.
Figure 10-3. Minimum Pulse Timings
INT0/1
Level-Triggered Interrupt
Edge-Triggered Interrupt
TCON.0/2
IT0/1
0
1
1 cycle
> 1 peripheral cycle
> 1 peripheral cycle
TCON.1/3
1 cycle
1 cycle
IE0/1
IEN0.0/2
EX0/1
AT89C5132
INT0/1
Interrupt
Request
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