MC68HC908GZ16 Datasheet, PDF (284/314 Pages) Motorola, Inc – Microcontrollers

Development Support
The monitor ROM firmware echoes each received byte back to the PTA0 pin for error checking. An 11-bit
delay at the end of each command allows the host to send a break character to cancel the command. A
delay of two bit times occurs before each echo and before READ, IREAD, or READSP data is returned.
The data returned by a read command appears after the echo of the last byte of the command.
NOTE
Wait one bit time after each echo before sending the next byte.
FROM HOST
READ
READ
ADDRESS ADDRESS ADDRESS ADDRESS
HIGH
HIGH
LOW
LOW
4
1
4
1
4
1
3, 2
ECHO
Notes:
1 = Echo delay, approximately 2 bit times
2 = Data return delay, approximately 2 bit times
3 = Cancel command delay, 11 bit times
4 = Wait 1 bit time before sending next byte.
Figure 20-13. Read Transaction
FROM HOST
DATA
4
RETURN
WRITE
WRITE
ADDRESS ADDRESS ADDRESS ADDRESS
HIGH
HIGH
LOW
LOW
DATA
DATA
3
1
3
1
3
1
3
1
2, 3
ECHO
Notes:
1 = Echo delay, approximately 2 bit times
2 = Cancel command delay, 11 bit times
3 = Wait 1 bit time before sending next byte.
Figure 20-14. Write Transaction
A brief description of each monitor mode command is given in Table 20-3 through Table 20-8.
Table 20-3. READ (Read Memory) Command
Description
Operand
Data Returned
Opcode
Read byte from memory
2-byte address in high-byte:low-byte order
Returns contents of specified address
$4A
Command Sequence
SENT TO MONITOR
READ
READ
ADDRESS ADDRESS ADDRESS ADDRESS
HIGH
HIGH
LOW
LOW
ECHO
DATA
RETURN
MC68HC908GZ16 • MC68HC908GZ8 Data Sheet, Rev. 1
284
Freescale Semiconductor