80C32E_03 Datasheet, PDF (4/20 Pages) AIMTEC – Rad. Tolerant 8-bit ROMless Microcontroller

Mnemonic
ALE
PSEN
EA
XTAL1
XTAL2
Type Name and Function
O (I)
Address Latch Enable: 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 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.
Program Store ENable: The read strobe to external program memory.
When executing code from the external program memory, PSEN is
O 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.
I
External Access Enable: EA must be externally held low to enable the
device to fetch code from external program memory locations.
I
Crystal 1: Input to the inverting oscillator amplifier and input to the
internal clock generator circuits.
O Crystal 2: Output from the inverting oscillator amplifier
4 80C32E
4149M–AERO–06/03