Z8F082ASH020SC datasheet(167/244 Pages) ZILOG

167 / 244 page

PS024705-0405

P R E L I M I N A R Y

On-Chip Debugger

Z8 Encore! XP® F08xA Series

Product Specification

149

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® F08xA Series

products 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 22

and 23 . The recommended method is the buffered implementation depicted in Figure 23 .

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 22.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

Z8F082ASH020SC Datasheet(PDF) 167 Page - Zilog, Inc.