Z8F021ASH020SC datasheet(191/276 Pages) ZILOG

191 / 276 page

PS022815-0206

On-Chip Debugger

Z8 Encore! XP® 4K Series

Product Specification

172

2. Wait 5ms for the internal reset sequence to complete.

3. Send the following bytes serially to the debug pin:

DBG

← 80H (autobaud)

DBG

← EBH

DBG

← 5AH

DBG

← 70H

DBG

← CDH (32-bit unlock key)

4. Release PA2/RESET. The PA0/DBG pin is now identical in function to that of the

DBG pin on the 20-/28-pin device. To enter DEBUG mode, re-autobaud and write

80H to the OCD control register. (See On-Chip Debugger Commands on page 172.)

Breakpoints

Execution Breakpoints are generated using the BRK instruction (opcode 00H). When the

eZ8 CPU decodes a BRK instruction, it signals the On-Chip Debugger. If Breakpoints are

enabled, the OCD enters DEBUG mode and idles the eZ8 CPU. If Breakpoints are not

enabled, the OCD ignores the BRK signal and the BRK instruction operates as an NOP

instruction.

Breakpoints in Flash Memory

The BRK instruction is opcode 00H, which corresponds to the fully programmed state of a

byte in Flash memory. To implement a Breakpoint, write 00H to the required break

address, overwriting the current instruction. To remove a Breakpoint, the corresponding

page of Flash memory must be erased and reprogrammed with the original data.

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® 4K Series products. When this option is enabled, several of the OCD

Z8F021ASH020SC 数据表(PDF) 191 Page - Zilog, Inc.

Z8F021ASH020SC 数据表(HTML) 191 Page - Zilog, Inc.

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 ...More

数据表下载