z16f2811 ZiLOG Semiconductor, z16f2811 Datasheet - Page 317

• Manufacturer Part Number: z16f2811
• Description: High Performance Microcontrollers
• Manufacturer: ZiLOG Semiconductor

PS022006-0207
DEBUG HALT Mode
Reading and Writing Memory
A clock change invalidates the baud reload value. Communication cannot continue until a
new autobaud reload value is set. As a result, the device automatically sends a serial break
to reset the communication link whenever a clock change occurs.
During debugging, it is appropriate to stop the CPU from executing instructions. This is
done by placing the device in DEBUG HALT mode. The operating characteristics of the
ZNEO Z16F Series devices in DEBUG HALT mode are:
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Entering DEBUG HALT mode
The device enters DEBUG HALT mode by any of the following operations:
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Exiting DEBUG HALT mode
The device exits DEBUG HALT mode by any of the following operations:
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Most debugging functions are accomplished by reading and writing control registers.
The OCD hardware has the capability of reading and writing memory when the CPU is
running.
When a read or write request from the OCD hardware occurs, the OCD steals the bus for
the number of cycles needed to complete the read or write operation. This bus stealing
occurs on a per byte basis, not a per command basis. Since the debugger operates serially,
it takes several clock cycles to transmit or receive a character.
If the debugger receives a command to read or write a block of memory, it will not steal
the bus for the entire read or write command. The debugger will only steal the bus for a
short period of time for each data byte. A debug write cycle will occur after a byte has
The ZNEO CPU fetch unit stops, idling the ZNEO CPU.
All enabled on-chip peripherals operate unless in STOP mode.
Constantly refreshes the WDT, if enabled.
Write the DBGHALT bit in the DBGCTL register to 1 using the OCD interface.
ZNEO CPU execution of
Hardware breakpoint match.
Clearing the
Power-on reset.
Voltage Brownout reset.
Asserting the RESET pin Low to initiate a Reset.
DBGHALT
bit in the DBGCTL register to 0.
P R E L I M I N A R Y
BRK
instruction (when enabled).
Product Specification
ZNEO
On-Chip Debugger
™
Z16F Series
303