z8f0813 ZiLOG Semiconductor, z8f0813 Datasheet - Page 166

• Manufacturer Part Number: z8f0813
• Description: High-performance 8-bit Microcontrollers
• Manufacturer: ZiLOG Semiconductor

PS024314-0308
OCD Unlock Sequence (8-Pin Devices Only)
Breakpoints
Runtime Counter
Because of pin-sharing on the 8-pin device, an unlock sequence must be performed to
access the DBG pin. If this sequence is not completed during a system reset, then the PA0/
DBG pin functions only as a GPIO pin.
The following sequence unlocks the DBG pin:
1. Hold PA2/RESET Low.
2. Wait 5 ms for the internal reset sequence to complete.
3. Send the following bytes serially to the debug pin:
4. Release PA2/RESET. The PA0/DBG pin is now identical in function to that of the
Execution breakpoints are generated using the
eZ8 CPU decodes a
OCD enters DEBUG mode and idles the eZ8 CPU. If breakpoints are not enabled, the
OCD ignores the BRK signal and the
Breakpoints in Flash Memory
The
byte in Flash memory. To implement a breakpoint, write
address, overwriting the current instruction. To remove a breakpoint, the corresponding
page of Flash memory must be erased and reprogrammed with the original data.
The OCD contains a 16-bit Runtime Counter. It counts system clock cycles between
breakpoints. The counter starts counting when the OCD leaves DEBUG mode and stops
counting when it enters DEBUG mode again or when it reaches the maximum count of
FFFFH
DBG
DBG
DBG
DBG
DBG
DBG pin on the 20- or 28-pin device. To enter DEBUG mode, re-autobaud and write
80H
BRK
.
←
←
←
←
←
to the OCD control register (see
instruction is opcode
80H (autobaud)
EBH
5AH
70H
CDH (32-bit unlock key)
BRK
instruction, it signals the OCD. If breakpoints are enabled, the
00H
, which corresponds to the fully programmed state of a
BRK
On-Chip Debugger Commands
instruction operates as an
BRK
instruction (opcode
Z8 Encore! XP
00H
to the required break
Product Specification
NOP
00H
®
On-Chip Debugger
instruction.
on page 157).
F0823 Series
). When the
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