Freescale Semiconductor Microcontrollers - Manual (Page 347)

MON08 Interface Connection
Device Class Description
347 Microcontrollers Debugger Manual
mode check and access the Flash on the processor. A simple reset is not enough; to pass
the security check, you must first force the processor to encounter a POR (power-on reset)
which requires that the processor's voltage dip below 0.1v. Once security is passed,
resetting the device or re-entering the software is easier. Class 3 selection also applies to
use of the ICS board with the two-pin blank part programming connector.
Class 4 Device
Custom Board (no ICS) with MON08 serial port circuitry and additional auto-reset circuit
built in. In this configuration, the ICS board is not used at all. The user must provide a
serial port connection from the PC and all hardware configuration necessary to force the
processor into MON08 mode upon reset. In addition, the user must include an extra circuit
which allows the reset line of the processor to be driven low from the DTR line of the
serial port connector (Pin 4 on a DB9). The following diagram shows the additional
connection needed to reset from a DB9 serial connector.
Figure 12.15 Reset Connection
In this configuration, because the software does not directly control power to the
processor, the user is prompted to turn the processor's power supply on and off. Turning
off the power supply is necessary to pass the initial security mode check and access the
Flash on the processor. A simple reset is not enough; to pass the security check, you must
first force the processor to encounter a POR (power-on reset) which requires the
processor's voltage to dip below 0.1v. Once security is passed, resetting the device is
facilitated by the above circuitry.