Atmel C51 Arkusz Danych Pobierz pdf (Strona 12)

AT89C51RB2/RC2

4180E–8051–10/06

PSEN 29 32 26 O Program Strobe 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 31 35 29 I External Access Enable: EA

must be externally held low to enable the device to

fetch code from external program memory locations 0000H to FFFFH (RD). If

security level 1 is programmed, EA

will be internally latched on Reset.

Table 12. Pin Description for 40 - 44 Pin Packages (Continued)

Mnemonic

Pin Number

Type Name and FunctionDIL LCC VQFP44 1.4

1 2 ... 7 8 9 10 11 12 13 14 15 16 17 ... 126 127

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