Z8F082ASJ020EG Datasheet, PDF (208/282 Pages) Zilog, Inc. – High-Performance 8-Bit Microcontrollers

Z8 Encore! XP^® F082A Series
Product Specification
191
in DEBUG Mode or the Flash Read Protect Option bit is enabled, this command reads and
discards one byte.
DBG ← 12H
DBG ← 1-5 byte opcode
On-Chip Debugger Control Register Definitions
This section describes the features of the On-Chip Debugger Control and Status registers.
OCD Control Register
The OCD Control Register controls the state of the On-Chip Debugger. This register is
used to enter or exit DEBUG Mode and to enable the BRK instruction. It can also reset the
Z8 Encore! XP F082A Series device.
A reset and stop function can be achieved by writing 81H to this register. A reset and go
function can be achieved by writing 41H to this register. If the device is in DEBUG Mode,
a run function can be implemented by writing 40H to this register.
Table 110. OCD Control Register (OCDCTL)
Bit
7
6
5
4
Field
DBGMODE BRKEN DBGACK
RESET
0
0
0
0
R/W
R/W
R/W
R/W
R
3
2
Reserved
0
0
R
R
1
0
RST
0
0
R
R/W
Bit
Description
[7]
DEBUG Mode
DBGMODE The device enters DEBUG Mode when this bit is 1. When in DEBUG Mode, the eZ8 CPU
stops fetching new instructions. Clearing this bit causes the eZ8 CPU to restart. This bit is
automatically set when a BRK instruction is decoded and Breakpoints are enabled. If the
Flash Read Protect Option Bit is enabled, this bit can only be cleared by resetting the
device. It cannot be written to 0.
0 = The Z8 Encore! XP F082A Series device is operating in NORMAL Mode.
1 = The Z8 Encore! XP F082A Series device is in DEBUG Mode.
[6]
BRKEN
Breakpoint Enable
This bit controls the behavior of the BRK instruction (opcode 00H). By default, Breakpoints
are disabled and the BRK instruction behaves similar to an NOP instruction. If this bit is 1,
when a BRK instruction is decoded, the DBGMODE bit of the OCDCTL Register is automati-
cally set to 1.
0 = Breakpoints are disabled.
1 = Breakpoints are enabled.
PS022827-1212
PRELIMINARY
On-Chip Debugger Control Register