Z8F021ASH020SC datasheet(187/276 Pages) ZILOG

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PS022815-0206

On-Chip Debugger

Z8 Encore! XP® 4K Series

Product Specification

168

Operation

OCD Interface

The on-chip debugger uses the DBG pin for communication with an external host. This

one-pin interface is a bi-directional, open-drain interface that transmits and receives data.

Data transmission is half-duplex, in that transmit and receive cannot occur simultaneously.

The serial data on the DBG pin is sent using the standard asynchronous data format

defined in RS-232. This pin creates an interface from the Z8 Encore! XP® 4K Series prod-

ucts to the serial port of a host PC using minimal external hardware.Two different methods

for connecting the DBG pin to an RS-232 interface are depicted in Figures 24 and 25 . The

recommended method is the buffered implementation depicted in Figure 25. The DBG pin

must always be connected to VDD through an external pull-up resistor.

For operation of the on-chip debugger, all power pins (VDD and AVDD)

must be supplied with power, and all ground pins (VSS and AVSS) must be

properly grounded.

The DBG pin is open-drain and must always be connected to VDD through

an external pull-up resistor to insure proper operation.

Figure 24.Interfacing the On-Chip Debugger’s DBG Pin with an RS-232 Interface (1)

Caution:

RS-232 TX

RS-232 RX

RS-232

Transceiver

VDD

DBG Pin

10KOhm

Schottky

Diode

Z8F021ASH020SC 数据表(PDF) 187 Page - Zilog, Inc.