Rainbow-electronics ATmega8515L Manual do Utilizador descarregar pdf (Página 59)

ATmega8515(L)

2512A–AVR–04/02

signal transition on the pin will be delayedbetween ½ and 1½ system clock period

depending upon thetimeof assertion.

When reading back a softwareassignedpin value, a

nop

instruction must beinserted as

indicated in Figure 31. The

out

instruction sets the“SYNC LATCH” signal at the positive

edge of the clock. Inthiscase, the delay t

through the synchronizer is one system

clock period.

Figure 31. Synchronization when Reading a SoftwareAssigned Pin Value

out PORTx, r16 nop in r17, PINx

0xFF

0x00 0xFF

SYSTEM CLK

r16

INSTRUCTIONS

SYNC LATCH

PINxn

r17

1 2 ... 54 55 56 57 58 59 60 61 62 63 64 ... 222 223

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Rainbow-electronics ATmega8515L Manual do Utilizador Página 59