Maxim-integrated Ultra-High-Speed Flash Microcontroller Manual do Utilizador descarregar pdf (Página 84)

6-17

Page Mode 1 Data Memory Timing–PAGES 1:0 = 10b (Four Cycles)

Figure 6-13 shows execution of the MOVX instruction from internal program memory with stretch value = 0 assigned (MD2:0 = 000b).

Note that the internal memory cycles consist of one system clock while the external memory cycles consist of four system clocks (page

hit) or eight system clocks (page miss).

Figure 6-14 illustrates the same MOVX instruction with a default stretch value (MD2:0 = 001b). The stretch cycle (four system clocks)

is distributed as follows: one system clock added for address setup, two system clocks being added to the RD or WR pulse duration,

and one system clock added for address/data hold. For subsequent stretch values of 2 or 3, the full stretch cycle is added to the dura-

tion of the RD or WR pulse.

Ultra-High-Speed Flash

Microcontroller User’s Guide

SYSCLK

ALE

PSEN

PORT2

PORT0

WR/RD

MOVX MSB MOVX LSB

DATA

MOVX INST INSTRUCTIONS

MOVX DATA ACCESS

(PAGE MISS)

SYSCLK

ALE

PSEN

PORT2

PORT0

WR/RD

MOVX INST INSTINST

MOVX DATA ACCESS

(PAGE MISS + 1 STRETCH CYCLE)

MOVX MSB MOVX LSB

MOVX DATA

= STRETCH CYCLE

Figure 6-14. Four-Cycle Page Mode 1: MOVX (Three Cycles)

Figure 6-13. Four-Cycle Page Mode 1: MOVX (Two Cycles)

Maxim Integrated

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Maxim-integrated Ultra-High-Speed Flash Microcontroller Manual do Utilizador Página 84