Z8F6421PM020SC Datasheet, PDF (214/299 Pages) Zilog, Inc. – High Performance 8-Bit Microcontrollers Z8 Encore-R 64K Series

Z8 Encore!^® 64K Series
Product Specification
194
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 can interface the 64K 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 37 and 38.
Caution:
For operation of the On-Chip Debugger, all power pins (V_DD and AV_DD)
must be supplied with power, and all ground pins (V_SS and AV_SS) must be
properly grounded.
The DBG pin is open-drain and must always be connected to V_DD through
an external pull-up resistor to ensure proper operation.
RS-232 TX
RS-232
Transceiver
V_DD
Diode
10K Ohm
DBG Pin
RS-232 RX
Figure 37. Interfacing the On-Chip Debugger’s DBG Pin with an RS-232 Interface (1)
PS019915-1005
On-Chip Debugger