AT80C51RD2 Atmel Corporation, AT80C51RD2 Datasheet - Page 52
AT80C51RD2
Manufacturer Part Number
AT80C51RD2
Description
Manufacturer
Atmel Corporation
Specifications of AT80C51RD2
Max. Operating Frequency
60 MHz
Cpu
8051-12C
Max I/o Pins
32
Spi
1
Uart
1
Sram (kbytes)
1.25
Operating Voltage (vcc)
2.7 to 5.5
Timers
4
Watchdog
Yes
Available stocks
Company
Part Number
Manufacturer
Quantity
Price
Company:
Part Number:
AT80C51RD2-RLRUM
Manufacturer:
NXP
Quantity:
8 243
Company:
Part Number:
AT80C51RD2-SLRUM
Manufacturer:
Atmel
Quantity:
967
Company:
Part Number:
AT80C51RD2-SLSUM
Manufacturer:
Atmel
Quantity:
1 445
Company:
Part Number:
AT80C51RD2-UM
Manufacturer:
FAIRCHIL
Quantity:
550
13. Keyboard Interface
13.0.1
13.0.2
52
AT80C51RD2
Interrupt
Power Reduction Mode
The AT80C51RD2 implement a keyboard interface allowing the connection of a 8 x n matrix key-
board. It is based on 8 inputs with programmable interrupt capability on both high or low level.
These inputs are available as alternate function of P1 and allow to exit from idle and power-
down modes.
The keyboard interfaces with the C51 core through 3 special function registers: KBLS, the Key-
board Level Selection register (Table 13-3), KBE, The Keyboard Interrupt Enable register
(Table 13-2), and KBF, the Keyboard Flag register (Table 13-1).
The keyboard inputs are considered as 8 independent interrupt sources sharing the same inter-
rupt vector. An interrupt enable bit (KBD in IE1) allows global enable or disable of the keyboard
interrupt (see Figure 13-1). As detailed in Figure 13-2 each keyboard input has the capability to
detect a programmable level according to KBLS.x bit value. Level detection is then reported in
interrupt flags KBF.x that can be masked by software using KBE.x bits.
This structure allow keyboard arrangement from 1 x n to 8 x n matrix and allows usage of P1
inputs for other purpose.
Figure 13-1. Keyboard Interface Block Diagram
Figure 13-2. Keyboard Input Circuitry
P1 inputs allow exit from idle and power-down modes as detailed in Section “Power-down
Mode”, page 56.
P1:x
P1.0
P1.1
P1.2
P1.3
P1.4
P1.5
P1.6
P1.7
V
CC
Internal Pull-up
Input Circuitry
Input Circuitry
Input Circuitry
Input Circuitry
Input Circuitry
Input Circuitry
Input Circuitry
Input Circuitry
KBLS.x
0
1
KBF.x
KBE.x
KBD
IE1
Keyboard Interface
Interrupt Request
KBDIT
4113D–8051–01/09