Rainbow-electronics ATmega128L Manual de usuario descargar pdf (Pagina 30)

ATmega128(L)

2467B–09/01

• Bit 6..4 - SRL2, SRL1, SRL0: Wait-state Sector Limit

It is possible to configure different wait-states for different external memory addresses.

The external memory address space can be divided in two sectors that have separate

wait-state bits. The SRL2, SRL1, and SRL0 bits select the split of the sectors, see

Table

and Figure 11. By default, the SRL2, SRL1, and SRL0 bits are set to zero and the

entire external memory address space is treated as one sector. When the entire SRAM

address space is configured as one sector, the wait-states are configured by the

SRW11 and SRW10 bits.

• Bit 1 and Bit 6 MCUCR - SRW11, SRW10: Wait-state Select Bits for Upper Sector

The SRW11 and SRW10 bits control the number of wait-states for the upper sector of

the external memory address space, see

Table 4.

• Bit 3..2 - SRW01, SRW00: Wait-state Select Bits for Lower Sector

The SRW01 and SRW00 bits control the number of wait-states for the lower sector of

the external memory address space, see

Table 4.

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

For further details of the timing and wait-states of the External Memory Interface, see

Figures 13 through Figures 16 for how the setting of the SRW bits affects the timing.

Table 3. Sector limits with different settings of SRL2..0

SRL2 SRL1 SRL0 Sector Limits

0 0 0 Lower sector = N/A

Upper sector = 0x1100-0xFFFF

0 0 1 Lower sector = 0x1100-0x1FFF

Upper sector = 0x2000-0xFFFF

0 1 0 Lower sector = 0x1100-0x3FFF

Upper sector = 0x4000-0xFFFF

0 1 1 Lower sector = 0x1100-0x5FFF

Upper sector = 0x6000-0xFFFF

1 0 0 Lower sector = 0x1100-0x7FFF

Upper sector = 0x8000-0xFFFF

1 0 1 Lower sector = 0x1100-0x9FFF

Upper sector = 0xA000-0xFFFF

1 1 0 Lower sector = 0x1100-0xBFFF

Upper sector = 0xC000-0xFFFF

1 1 1 Lower sector = 0x1100-0xDFFF

Upper sector = 0xE000-0xFFFF

Table 4. Wait States

(1)

SRWn1 SRWn0 Wait States

0 0 No wait-states

0 1 Wait one cycle during read/write strobe

1 0 Wait two cycles during read/write strobe

1 1 Wait two cycles during read/write and wait one cycle before driving out

new address

1 2 ... 25 26 27 28 29 30 31 32 33 34 35 ... 330 331

Comentarios a estos manuales

Sin comentarios

Rainbow-electronics ATmega128L Manual de usuario Pagina 30

Comentarios a estos manuales

Relacionado con productos y manuales para Sensores Rainbow-electronics ATmega128L