Z8F6421PM020SC Datasheet, PDF (222/299 Pages) Zilog, Inc. – High Performance 8-Bit Microcontrollers Z8 Encore-R 64K Series

Z8 Encore!^® 64K Series
Product Specification
202
the 16-bit CRC-CCITT polynomial. If the device is not in DEBUG mode, this
command returns FFFFH for the CRC value. Unlike most other OCD Read
commands, there is a delay from issuing of the command until the OCD returns the
data. The OCD reads the Program Memory, calculates the CRC value, and returns the
result. The delay is a function of the Program Memory size and is approximately equal
to the system clock period multiplied by the number of bytes in the Program Memory.
DBG ← 0EH
DBG → CRC[15:8]
DBG → CRC[7:0]
• 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 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 instructions where the first byte of the instruction has been
overwritten by a Breakpoint. If the device is not in DEBUG mode or the Read Protect
Option Bit is enabled, the OCD ignores this command.
DBG ← 11H
DBG ← opcode[7:0]
• Execute Instruction (12H)—The Execute Instruction command allows sending an
entire instruction to be executed to the eZ8 CPU. This command can also step over
Breakpoints. The number of bytes to send for the instruction depends on the opcode. If
the device is not in DEBUG mode or the Read Protect Option Bit is enabled, the OCD
ignores this command
DBG ← 12H
DBG ← 1-5 byte opcode
On-Chip Debugger Control Register Definitions
OCD Control Register
The OCD Control register (Table 101) controls the state of the On-Chip Debugger. This
register enters or exits DEBUG mode and enables the BRK instruction. It can also reset
the Z8F642x familyZ8R642x family device.
PS019915-1005
On-Chip Debugger