Monitor ROM (MON)
Security
MC68HC908MR16/MC68HC908MR32 — Rev. 4.0 Advance Information
MOTOROLA Monitor ROM (MON) 197
Figure 10-6. Monitor Mode Entry Timing
To determine whether the security code entered is correct, check to see
if bit 6 of RAM address $60 is set. If it is, then the correct security code
has been entered and FLASH can be accessed.
If the security sequence fails, the device can be reset (via power-pin
reset only) and brought up in monitor mode to attempt another entry.
After failing the security sequence, the FLASH mode can also be bulk
erased by executing an erase routine that was downloaded into internal
RAM. The bulk erase operation clears the secu rity code locations so th at
all eight security bytes become $FF.
BYTE 1
BYTE 1 ECHO
BYTE 2
BYTE 2 ECHO
BYTE 8
BYTE 8 ECHO
COMMAND
COMMAND ECHO
PA0
PA7
RST
VDD
4096 + 32 CGMXCLK CYCLES
24 BUS CYCLES
256 BUS CYCLES (MINIMUM)
131121
BREAK
NOTES:
2 = Data return delay, 2 bit times
3 = Wait 1 bit time before sending next byte.
3
FROM HOST
FROM MCU
1 = Echo delay, 2 bit times