Rainbow-electronics ATmega161L Manual de usuario descargar pdf (Pagina 137)

137

ATmega161(L)

1228C–AVR–08/02

Figure 85. External Memory Timing (SRWn1 = 1, SRWn0 = 0)

Figure 86. External Memory Timing (SRWn1 = 1, SRWn0 = 1)

(1)

Note: 1. The ALE pulse in the last period (T4 - T7) is only present if the next instruction

accesses the RAM (internal or external). The data and address will only change in T4

- T7 if ALE is present (the next instruction accesses the RAM).

ALE

Address [15..8]

AddressXX

Read

Data/Address [7..0]

Address

Data

Write

Data/Address [7..0]

Address Data

T1 T2 T3

Prev. addr.

Prev. data

System Clock Ø

ALE

Address [15..8]

AddressXX

Read

Data/Address [7..0]

Address

Data

Write

Data/Address [7..0]

Address

Data

T1 T2 T3

8 12

Prev. addr.

Prev. data

System Clock Ø

1 2 ... 132 133 134 135 136 137 138 139 140 141 142 ... 158 159

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Rainbow-electronics ATmega161L Manual de usuario Pagina 137