80C54 Ver la hoja de datos (PDF) - Atmel Corporation
Número de pieza
componentes Descripción
Fabricante
80C54 Datasheet PDF : 62 Pages
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AT/TS8xC54/8X2
Table 5-1. Pin Description for 40/44 pin packages
MNEMONIC
PIN NUMBER
DIL LCC VQFP 1.4
TYPE
Name And Function
MNEMONIC
PIN NUMBER
TYPE NAME AND FUNCTION
ALE/PROG
30
33
27
O (I) Address Latch Enable/Program Pulse: Output pulse for latching the low byte of the
address during an access to external memory. In normal operation, ALE is emitted at a
constant rate of 1/6 (1/3 in X2 mode) the oscillator frequency, and can be used for
external timing or clocking. Note that one ALE pulse is skipped during each access to
external data memory. This pin is also the program pulse input (PROG) during EPROM
programming. ALE can be disabled by setting SFR’s AUXR.0 bit. With this bit set, ALE
will be inactive during internal fetches.
PSEN
29
32
26
O Program Store ENable: The read strobe to external program memory. When
executing code from the external program memory, PSEN is activated twice each
machine cycle, except that two PSEN activations are skipped during each access to
external data memory. PSEN is not activated during fetches from internal program
memory.
EA/VPP
31
35
29
I
External Access Enable/Programming Supply Voltage: EA must be externally held
low to enable the device to fetch code from external program memory locations 0000H
and 3FFFH (54X2) or 7FFFH (58X2). If EA is held high, the device executes from
internal program memory unless the program counter contains an address greater
than 3FFFH (54X2) or 7FFFH (58X2). This pin also receives the 12.75V programming
supply voltage (VPP) during EPROM programming. If security level 1 is programmed,
EA will be internally latched on Reset.
XTAL1
19
21
15
I
Crystal 1: Input to the inverting oscillator amplifier and input to the internal clock
generator circuits.
XTAL2
18
20
14
O Crystal 2: Output from the inverting oscillator amplifier
7
4431E–8051–04/06
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