Z80230 查看數據表（PDF） - Zilog

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Z80230

Zilog SCC Serial Communication Controller

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Application Note

The Z180™ Interfaced with the SCC at MHZ

Table 8. Parameter Equations Worst Case (Without Delay Signals - No Wait State)

SCC

Parameters

TsA(RD)

TdA(DR)

TdRDf(DR)

TwRDI

TsA(WR)

TsDW(WR)

TwWRI

Z180

Equation

tcyc-tAD+tRDD1

3tcyc+tCHW+tcf-tAD-tDRS

2tcyc+tCHW+tcf-tRDD1-tDRS

2tcyc+tCHW+tcf-tDRS+tRDD2

tcyc-tAD+tWRD1

tWDS

tWRP

Value

30 min

245 min

160 min

185 min

30 min

15 min

210 min

Units

7

ns

ns

ns

ns

ns

ns

ns

Z180

Parameters

tDRS

Table 9. Parameter Equations

SCC

Equation

Address

3tcyc+tCHW-tAD-TdA(DR)

RD

2tcyc+tCHW-tRDD1-TdRD(DR)

Value

241 min

184 min

Units

ns

ns

I/O Read Cycle

These tables show that a delay of the falling edge of /RD

satisfies the SCC TsA(RD) timing requirement of 50 ns

min. The Z180 calculated value is 30 ns min for the worst

case. Also, Z180 timing specification tAH (Address Hold

time) is 10 ns min. The SCC timing parameters ThA(RD)

{Address to /RD High Hold} and ThCE(RD) {/CE to /RD

High Hold} are minimum at 0 ns. The rising edge of /RD is

early to guarantee these parameters when considering

address decoders and gate propagation delays.

I/O Write Cycle

Delay the falling edge of /WR to satisfy the SCC TsA(/WR)

timing requirement of 50 ns min. The Z180 calculates 30

ns min worst case. Further, the Z180 timing specifications

tAH (Address Hold time) and tWDH (/WR high to data hold

time) are both 10 ns min. The SCC timing parameters

ThA(WR) {Address to /WR High Hold}, ThCE(WR) {/CE to

/WR High Hold} and TdWR(W) {Write data to /WR High

hold} are a minimum of 0 ns. The rising edge of /WR is

early to guarantee these parameter requirements.

This circuit depicts logic for the I/O interface and the

Interrupt Acknowledge Interface for 10 MHz clock of

operation. Figure 13 is the I/O read/write timing chart

(discussions of timing considerations on the Interrupt

Acknowledge cycle and the circuit using EPLD occur

later).

UM010901-0601

6-39

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