Z8F082ASH020SC datasheet(171/244 Pages) ZILOG

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PS024705-0405

P R E L I M I N A R Y

On-Chip Debugger

Z8 Encore! XP® F08xA Series

Product Specification

153

Runtime Counter

The On-Chip Debugger contains a 16-bit Runtime Counter. It counts system clock cycles

between Breakpoints. The counter starts counting when the On-Chip Debugger leaves

DEBUG mode and stops counting when it enters DEBUG mode again or when it reaches

the maximum count of FFFFH.

On-Chip Debugger Commands

The host communicates to the On-Chip Debugger by sending OCD commands using the

DBG interface. During normal operation, only a subset of the OCD commands are avail-

able. In DEBUG mode, all OCD commands become available unless the user code and

control registers are protected by programming the Flash Read Protect Option bit (FRP).

The Flash Read Protect Option bit prevents the code in memory from being read out of the

Z8 Encore! XP® F08xA Series products. When this option is enabled, several of the OCD

commands are disabled. Table 99 on page 158 is a summary of the On-Chip Debugger

commands. Each OCD command is described in further detail in the bulleted list follow-

ing this table. Table 99 also indicates those commands that operate when the device is not

in DEBUG mode (normal operation) and those commands that are disabled by program-

ming the Flash Read Protect Option bit.

Debug Command

Command

Byte

Enabled when NOT

in DEBUG mode?

Disabled by

Flash Read Protect Option Bit

Read OCD Revision

00H

Yes

–

Reserved

01H

–

Read OCD Status Register

02H

Yes

–

Read Runtime Counter

03H

–

Write OCD Control Register

04H

Yes

Cannot clear DBGMODE bit

Read OCD Control Register

05H

Yes

–

Write Program Counter

06H

–

Disabled

Read Program Counter

07H

–

Disabled

Write Register

08H

–

Only writes of the Flash Memory Control

registers are allowed. Additionally, only

the Mass Erase command is allowed to

be written to the Flash Control register.

Read Register

09H

–

Disabled

Write Program Memory

0AH

–

Disabled

Read Program Memory

0BH

–

Disabled

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