Atmel AT91SAM7L-STK - Manual (Page 20)

Board Description
4-6 AT91SAM7L-STK Rev. B Starter Kit User Guide
6414A–ATARM–12-Sep-08
Figure 4-4. Clock Circuit of the AT91SAM7L-STK
4.7 Reset and Wake Up Circuitry
There is one RESET button for external reset control of the AT91SAM7L128 and one WAKEUP button
for waking the system up from off mode. The first time the board is powered, it will go directly into OFF
mode. The WAKEUP button must be pushed to bring the chip out of OFF mode. After pushing the
RESET button, the chip will go back into OFF mode.
4.7.1 Debug Considerations
Before launching a debug session, the user must ensure the core is running. The low power modes, Off
mode and Backup mode, will prevent debugging the project.
Recovery Procedure:
1. The Flash must be erased: connect ERASE Jumper J6, pins 39-40.
2. Press RESET button (NRSTB pin): OFF mode is entered.
3. Exit OFF mode by pressing WAKE UP button (FWUP pin)
4. The chip enters Active mode and Flash is erased.
5. Remove ERASE Jumper J6, pins 39-40.
6. Press RESET button (NRSTB pin)
7. Exit OFF mode by pressing WAKE UP button (FWUP pin)
Note: Step 1 to 5 may be skipped if no application using a low power mode is running out of Flash.
4.8 Power Supply and Management
The AT91SAM7L-STK board is supplied with two AAA batteries, to be set in the battery holder (J1).
Therefore the board is 3.0 Vcc powered. There are also two pads (J2 and J3) for external power supply.
Users can manually solder two power wires to these pads in order to power the board from an external
power supply, to be set within the AT91SAM7L128 acceptable voltage range: 1.8V to 3.6V.
Warning: If an external power source is used, the batteries must be removed.
J9 is used for power current measurement for the whole board.