4.5.1.
Operation at Other Voltages
The SAM L22 Xplained Pro board is operated at 3.3V by default, but it also has the possibility of running
at lower voltages from an external supply. The EDBG is designed to run from a 3.3V supply and won't
work on other voltages, therefore all connections from the EDBG and the on board 3.3V regulator to the
ATSAML22N18A should be removed.
To completely disconnect the EDBG and the on-board power supply from the ATSAML22N18A do the
following:
•
Remove the two jumpers from the on-board 3-pin current measurement headers (J101 and J102),
and connect the two center pins (pin 2) together with a wire or an ammeter as shown in
SAM L22 Xplained Pro Current Measurement Headers
•
Remove R400, R404, R405, R406, R407, R408, R414, R415, R416, R417, R418, R419, R420,
R425, R426, R427, R600, R601
•
Optionally cut J100 to remove power to the on-board current measurement headers (J101 and
J102) from the on-board regulator
Figure 4-6 SAM L22 Xplained Pro EDBG Disconnect
on page 33 shows all components that have to be
removed from the bottom side of the PCB for operation at other voltages. To locate the other components,
see the assembly drawing in the section above. When the components are removed, the kit can be
supplied with a desired voltage through the pins marked 3.3V (pin four) and GND (pin two) on the
Xplained Pro power header. To program and debug the ATSAML22N18A the 2x5 50mil Cortex debug
connector has to be used with an external debugger.
Info:
Operating the ATSAML22N18A on other voltages than 3.3V requires physical
modifications on the kit using a soldering iron and an external debugger for programming the
ATSAML22N18A. The on-board current measurement only works at 3.3V. The on-board LED is
selected for 3.3V operation, the light level at 1.8V operation is very low. To increase the emitted
light level the value of the series resistor can be lowered. The EDBG functionality can be
restored by re-soldering the removed components and soldering a 0Ω resistor over J100.
Caution:
The voltage supplied through the power header is applied directly to the
ATSAML22N18A and the extension headers, applying a voltage greater than 3.3V may damage
the board permanently.
Figure 4-6. SAM L22 Xplained Pro EDBG Disconnect
Atmel SAM L22 Xplained Pro [USER GUIDE]
Atmel-42474B-SAM-L22-Xplained-Pro_User Guide-12/2015
33
