Z8 Encore! XP® F08xA Series
Product Specification
158
On-Chip Debugger Control Register Definitions
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 BRKinstruction. It can also reset the
Z8 Encore! XP® F08xA Series device.
A reset and stop function can be achieved by writing 81Hto this register. A reset and go
function can be achieved by writing 41Hto this register. If the device is in DEBUG mode,
a run function can be implemented by writing 40H to this register.
.
Table 99. OCD Control Register (OCDCTL)
BITS
7
6
5
4
3
2
1
0
DBGMODE BRKEN DBGACK
Reserved
RST
FIELD
RESET
R/W
0
0
0
0
0
0
0
0
R/W
R/W
R/W
R
R
R
R
R/W
DBGMODE—Debug Mode
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® F08xA Series device is operating in NORMAL mode.
1 = The Z8 Encore! XP® F08xA Series device is in DEBUG mode.
BRKEN—Breakpoint Enable
This bit controls the behavior of the BRKinstruction (opcode 00H). By default, Break-
points are disabled and the BRKinstruction behaves similar to an NOP instruction. If this
bit is 1, when a BRKinstruction is decoded, the DBGMODEbit of the OCDCTL register is
automatically set to 1.
0 = Breakpoints are disabled.
1 = Breakpoints are enabled.
DBGACK—Debug Acknowledge
This bit enables the debug acknowledge feature. If this bit is set to 1, the OCD sends a
Debug Acknowledge character (FFH) to the host when a Breakpoint occurs.
0 = Debug Acknowledge is disabled.
1 = Debug Acknowledge is enabled.
Reserved—Must be 0.
RST—Reset
Setting this bit to 1 resets the Z8 Encore! XP® F08xA Series device. The device goes
PS024705-0405
P R E L I M I N A R Y
On-Chip Debugger
ZILOG [ ZILOG, INC. ]
