Z8 Encore! XP® 4K Series
Product Specification
177
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Step Instruction (10H)—The Step Instruction command steps one assembly instruction
at the current Program Counter (PC) location. If the device is not in DEBUG mode or the
Flash Read Protect Option bit is enabled, the OCD ignores this command.
DBG ← 10H
Stuff Instruction (11H)—The Stuff Instruction command steps one assembly instruction
and allows specification of the first byte of the instruction. The remaining 0-4 bytes of the
instruction are read from Program Memory. This command is useful for stepping over in-
structions where the first byte of the instruction has been overwritten by a Breakpoint. If
the device is not in DEBUG mode or the Flash Read Protect Option bit is enabled, the
OCD ignores this command.
DBG ← 11H
DBG ← opcode[7:0]
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Execute Instruction (12H)—The Execute Instruction command allows sending an en-
tire instruction to be executed to the eZ8 CPU. This command can also step over Break-
points. The number of bytes to send for the instruction depends on the opcode. If the device
is not 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
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® 4K 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 109. 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
PS022815-0206
On-Chip Debugger
ZILOG [ ZILOG, INC. ]
