STLC5464 datasheet(71/83 Pages) STMICROELECTRONICS

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U,V,W,Z : These four bits define the different signals delivered by the MHDLC.

First Case : the external RAM circuit is DRAM (T = 1 or S = 1)

- U defines the time Tu comprised between beginning of cycle and falling edge of NRAS :

U = 1, Tu = 60ns - U = 0, Tu = 30ns

- V defines the time Tv comprised between falling edge of NRAS and falling edge of NCAS :

V = 1, Tv = 60ns - V = 0, Tv = 30ns

- W defines the time Tw comprised between falling edge of NCAS and rising edge of NCAS :

W = 1, Tw = 60ns - W = 0, Tw = 30ns

- Z defines the time Tz comprised between rising edge of NCAS and end of cycle :

Z = 1, Tz = 60ns - Z = 0, Tz = 30ns

The total cycle is Tu + Tv + Tw + Tz.

The different output signals are high impedance during 15ns before the end of each cycle.

Second Case : the external RAM circuit is SRAM (T = 0 or S = 0)

- U and V define a part of write cycle for SRAM : the time Tuv comprised between falling edge

and rising edge of NCE. The total of write cycle is : 15ns+Tuv + 15ns.

Tuv

30ns

60ns

90ns

120ns

- W and Z define a part of read cycle for SRAM : the time Twz comprised between falling edge

of NOE and rising edge of NOE. The total of read cycle is : Twz +30ns

Twz

30ns

60ns

90ns

120ns

N.B. The different output signals are high impedance during 15ns before the end of each cycle. On the outside of each (DRAM

or SRAM) cycle all the outputs are high impedance or not in accordance with MBL bit (see ”MBL : Memory Bus Low

impedance”).

Memory

bit15

bit8

bit7

bit 0

P4E1 P4E0 P3E1 P3E0 P2E1 P2E0 P1E1 P1E0

REF

After reset (E400)H

P1 E0/1 : PRIORITY 1 for entity defined by E0/1

P2 E0/1 : PRIORITY 2 for entity defined by E0/1

P3 E0/1 : PRIORITY 3 for entity defined by E0/1

P4 E0/1 : PRIORITY 4 for entity defined by E0/1

Entity definition :

Entity

Rx DMA Controller

Microprocessor

Tx DMA Controller

Interrupt Controller

VIII - INTERNAL REGISTERS (continued)

STLC5464

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