Freescale Semiconductor Microcontrollers Tpu and Tpd Timing Textboxes, Target has RESET Button, MON08 Cable Connection Communications Type

HC08 ICS P&E Multilink/Cyclone Pro Connections

Connection Procedure

385

Microcontrollers Debugger Manual

Tpu and Tpd Timing Textboxes

Tpu and Tpd set the power-up and power-down delay (respectively) that is observed when

power-cycling a target for entry into Monitor Mode. These settings are only valid for

devices with automatically controlled power.

Whenever power is automatically or manually switched off, the software waits for an

amount of time equal to the Tpd delay time before proceeding to the connection protocol.

This is because a board or power supply may have capacitance which holds the power up

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 M68HC08

processor. This is to allow time not only for power to be fully available, but to allow all

reset drivers to release the RESET line.

In using Class III boards, the software occasionally needs to get control of the target. For a

more detailed description of device classes, see Device Class Description. On systems

which are Class III boards with the monitor mode circuitry built-in (including 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 prompts the user to power cycle the

target system to achieve a reset.

This selection box is valid only for Class II hardware configurations using the MON08

cable. It allows the user to specify the sequence that the software uses to power up the ICS

system. For a more detailed description of device classes, see Device Class Description.

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.