Block Guide — S12BDM V4

19

NOTE:

If enabled, ACK will occur when data is ready for transmission for all BDM READ commands and will occur after the write

is complete for all BDM WRITE commands.

The READ_BD and WRITE_BD commands allow access to the BDM register locations. These locations

are not normally in the system memory map but share addresses with the application in memory. To

distinguish between physical memory locations that share the same address, BDM memory resources are

enabled just for the READ_BD and WRITE_BD access cycle. This allows the BDM to access BDM

locations unobtrusively, even if the addresses conflict with the application memory map.

Table 4-1 Hardware Commands

Command

Opcode

(hex)

Data

Description

BACKGROUND

90

None

Enter background mode if firmware is enabled. If enabled,

an ACK will be issued when the part enters active background

mode.

ACK_ENABLE

D5

None

Enable Handshake. Issues an ACK pulse after the command

is executed.

ACK_DISABLE

D6

None

Disable Handshake. This command does not issue an

ACK pulse.

READ_BD_BYTE

E4

16-bit address

16-bit data out

Read from memory with standard BDM firmware lookup table

in map. Odd address data on low byte; even address data on

high byte.

READ_BD_WORD

EC

16-bit address

16-bit data out

Read from memory with standard BDM firmware lookup table

in map. Must be aligned access.

READ_BYTE

E0

16-bit address

16-bit data out

Read from memory with standard BDM firmware lookup table

out of map. Odd address data on low byte; even address data

on high byte.

READ_WORD

E8

16-bit address

16-bit data out

Read from memory with standard BDM firmware lookup table

out of map. Must be aligned access.

WRITE_BD_BYTE

C4

16-bit address

16-bit data in

Write to memory with standard BDM firmware lookup table in

map. Odd address data on low byte; even address data on

high byte.

WRITE_BD_WORD

CC

16-bit address

16-bit data in

Write to memory with standard BDM firmware lookup table in

map. Must be aligned access.

WRITE_BYTE

C0

16-bit address

16-bit data in

Write to memory with standard BDM firmware lookup table out

of map. Odd address data on low byte; even address data on

high byte.

WRITE_WORD

C8

16-bit address

16-bit data in

Write to memory with standard BDM firmware lookup table out

of map. Must be aligned access.