Rainbow-electronics ATmega8515L Uživatelský manuál stáhnout pdf (Strana 28)

ATmega8515(L)

2512A–AVR–04/02

SRAM address spaceisconfigured as one sector, the wait states are configuredbythe

SRW11 andSRW10 bits.

• Bit 1 and Bit 6 MCUCR – SRW11, SRW10: Wait State Select Bits for Upper

Sector

The SRW11 andSRW10 bitscontrol thenumber ofwait statesfor theuppersector of

the ExternalMemory address space,see Table 3.

• Bit 3..2 – SRW01, SRW00: Wait State Select Bits for Lower Sector

The SRW01 andSRW00 bitscontrol thenumber ofwait statesfor the lowersector of

the ExternalMemory address space,see Table 3.

Note: 1. n = 0or 1 (lower/uppersector).

Forfurtherdetails of thetimingandwait states of the ExternalMemory Interface,see

Figure13 to Figure16how the setting of the SRWbits affects the timing.

Table 2. SectorLimitswithDifferent Settings ofSRL2..0

SRL2 SRL1 SRL0 Sector Limits

000

Lowersector=N/A

Uppersector=0x0260 - 0xFFFF

001

Lowersector=0x0260 - 0x1FFF

Uppersector=0x2000 - 0xFFFF

010

Lowersector=0x0260 - 0x3FFF

Uppersector=0x4000 - 0xFFFF

011

Lowersector=0x0260 - 0x5FFF

Uppersector=0x6000 - 0xFFFF

100

Lowersector=0x0260 - 0x7FFF

Uppersector=0x8000 - 0xFFFF

101

Lowersector=0x0260 - 0x9FFF

Uppersector=0xA000 - 0xFFFF

110

Lowersector=0x0260 - 0xBFFF

Uppersector=0xC000 - 0xFFFF

111

Lowersector=0x0260 - 0xDFFF

Uppersector=0xE000 - 0xFFFF

Table 3. Wait States

(1)

SRWn1 SRWn0 Wait States

00No wait states.

01Wait one cycle during read/write strobe.

10Wait two cyclesduring read/write strobe.

Wait two cyclesduring read/write andwait one cycle before driving out

new address.

1 2 ... 23 24 25 26 27 28 29 30 31 32 33 ... 222 223

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