Z8F640x/Z8F480x/Z8F320x/Z8F240x/Z8F160x
Z8 Encore!®
152
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 Z8F640x family device 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 87 and 88.
Caution:
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 ensure proper operation.
VDD
RS-232
Transceiver
10K Ohm
DBG Pin
Diode
RS-232 TX
RS-232 RX
Figure 87. Interfacing the On-Chip Debugger’s DBG Pin with an RS-232 Interface (1)
PS017610-0404
On-Chip Debugger
ZILOG [ ZILOG, INC. ]
