Z8F1680SH020SG Datasheet, PDF (333/412 Pages) Zilog, Inc. – High-Performance 8-Bit Microcontrollers

Z8 Encore! XP^® F1680 Series
Product Specification
308
DBG ← Size[7:0]
DBG → 1-65536 data bytes
Read Program Memory CRC (0EH). The Read Program Memory CRC command com-
putes and returns the CRC (cyclic redundancy check) of Program memory using the 16-bit
CRC-CCITT polynomial (x¹⁶ + x¹² + x⁵ + 1). The CRC is preset to all 1s. The least-signif-
icant bit of the data is shifted through the polynomial first. The CRC is inverted when it is
transmitted. 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 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
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 op code. If the device is not
in DEBUG mode or the Read Protect option bit is enabled, the OCD ignores this com-
mand.
DBG ← 12H
DBG ← 1-5 byte opcode
Write Line Control Register (18H). The Write Line Control Register command writes the
data that follows to the Line Control Register.
DBG ← 18H
DBG ← LCR[7:0]
Read Line Control Register (19H). The Read Line Control Register command returns
the current value in the Line Control Register.
DBG ← 19H
DBG → LCR[7:0]
PS025015-1212
PRELIMINARY
On-Chip Debugger