Freescale Semiconductor Microcontrollers - Manual (Page 336)

MON08 Interface Connection
Connection Procedure
336 Microcontrollers Debugger Manual
for a short time after the supply has been switched off, but the supply voltage must reach
less than 0.1v before it is turned back on if a Power-On reset is to occur.
Whenever power is automatically or manually switched on, the software waits for an
amount of time equal to the Tpu delay time before attempting to contact the 68HC08
processor. This is to allow time not only for power to be fully available, but to wait until
any reset driver has finally released the RESET line.
Target Has RESET Button
With a class III board, the software occasionally needs to get control of the target. On
systems which are Class III boards with the monitor mode circuitry built-in (including an
RS-232 driver), there is no means to reset the target to gain control. If the board has a reset
button, the software can use this to gain control of the target system. If this option is
checked, the software prompts the user to push the target reset button when a reset of the
target system is desired. If the option is unchecked, the software asks the user to power
cycle the target system to achieve a reset.
For a detailed description of the board or device classes, see Device Class Description .
MON08 Cable Connection Communications Type
This selection box is valid only for Class II hardware configurations using the MON08
cable. For a detailed description of the board or device classes, see
Device Class
Description . It allows the user to specify the sequence that the software uses to power up
the ICS system. When the software tries to create a power-on reset condition, two events
must occur:
1. Power of the target MCU must go below 0.1v. This means that the processor cannot be
receiving power from its power pins, nor can it have a significant voltage being driven
on port pins or the IRQ line, as these drive the MCU power back through these pins. It
is crucial, therefore, to have the ICS and the Target both powered down at some point
in time.
2. The processor MON08 configuration pins, including IRQ, must be properly driven
when the target processor resets to drive it into monitor mode. If these pins are not set
up properly before the processor powers up, the processor may start up in user mode.