TS87C51RC2 ATMEL Corporation, TS87C51RC2 Datasheet - Page 8

• Manufacturer Part Number: TS87C51RC2
• Description: High Performance 8-bit Microcontroller 32 Kbytes Otp
• Manufacturer: ATMEL Corporation

TS80C51RA2/RD2
TS83C51RB2/RC2/RD2
TS87C51RB2/RC2/RD2
8
ALE/PROG
PSEN
EA/V
XTAL1
XTAL2
Mnemonic
PP
30
29
31
19
18
Pin Number
33
32
35
21
20
27
26
29
15
14
Type
O (I)
O
O
I
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.
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.
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 (RB) or 7FFFH (RC), or FFFFH (RD). If EA is
held high, the device executes from internal program memory unless the program
counter contains an address greater than 3FFFH (RB) or 7FFFH (RC) EA must
be held low for ROMless devices. This pin also receives the 12.75V programming
supply voltage (V
programmed, EA will be internally latched on Reset.
Crystal 1: Input to the inverting oscillator amplifier and input to the internal
clock generator circuits.
Crystal 2: Output from the inverting oscillator amplifier
PP
) during EPROM programming. If security level 1 is
Name And Function
Rev. C - 06 March, 2001