AM85C30 datasheet(157/194 Pages) AMD

157 / 194 page

SCC Application Notes

AMD

7–8

7.2.2

SCC Interface

Figure 7–2 shows the SCC to CPU interface required for this application. The 8-bit data

bus and control lines all come from the user’s CPU. The Am8530 control lines are

RD,

WR, A/B, D/C and CE. PCLK comes from the system clock, or an external crystal, up to

the maximum rate of the SCC. The IEI and the

INTACK pins should be pulled up. The

baud-rate generator clock is connected to the

RTxC pin.

7.2.3

SCC Initialization

Initialization of the SCC for polled asynchronous communication is divided into two parts;

part one programs the operating modes of the SCC and part two enables them (refer to

Table 7–4). Care must be taken when writing the software to meet the SCC’s Cycle and

Reset Recovery times. The Cycle Recovery time, 6 PCLK cycles, applies to the period

between any Read or Write cycles affecting the SCC. The Reset Recovery time is the

period after a hardware reset caused either by hardware or software; this recovery time

extends the Cycle Recovery time to 11 PCLK cycles.

Data

Control

System

VCC VCC

XTAL

OSC

2.4576 MHz

OSC

PCLK

RTxC

INTACK

IEI

D0 – D7

SCC

Pin 12 For Channel A

Pin 28 For Channel B

Figure 7–2. SCC Interface

AM85C30 데이터시트(PDF) 157 Page - Advanced Micro Devices