User manual

Atmel SAM D21 Xplained Pro [USER GUIDE]

42220A-MCU-02/2014

cutting the strap and adding a resistor across the strap. More information about oscillator allowance and safety

factor can be found in appnote AVR4100

Table 4-4. External 32.768kHz Crystals

Pin on SAM D21 Function

PA00 XIN32

PA01 XOUT32

4.2.2 Mechanical Buttons

SAM D21 Xplained Pro contains two mechanical buttons. One button is the RESET button connected to the

SAM D21 reset line and the other is a generic user configurable button. When a button is pressed it will drive

the I/O line to GND.

Table 4-5. Mechanical Buttons

Pin on SAM D21 Silkscreen text

RESETN RESET

PA15 SW0

4.2.3 LED

There is one yellow LED available on the SAM D21 Xplained Pro board that can be turned on and off. The LED

can be activated by driving the connected I/O line to GND.

Table 4-6. LED Connections

Pin on SAM D21 LED

PB30 Yellow LED0

4.2.4 USB

The SAM D21 Xplained Pro has a micro USB receptable for use with the SAM D21 USB module. To be able to

detect when a USB cable is connected, a GPIO is used to detect the VBUS voltage on the connector. The USB

ID line is used to detect if a host mode cable is connected and will automatically switch on the power to the

USB connector. The I/O connected to USB ID can be used to read the status of the line or manually override

the voltage output. For other modes on the USB ID lines, refer to the USB organization specifications.

Table 4-7. USB Connections

Pin on SAM D21 USB

PA14 VBUS Detection

PA03 USB ID

PA24 USB D-

PA25 USB D+

4.2.5 Serial Flash

The SAM D21 Xplained Pro has an onboard 8Mbit serial flash for non-voltatile storage of data.

Table 4-8. Serial Flash Connections

Pin on SAM D21 Function Serial Flash Shared functionality

PA13 GPIO #CS EXT3 PIN8 (default

disconnected)

PB22 SERCOM5 PAD[2] SPI MOSI SI EXT3 and EDBG

PB16 SERCOM5 PAD[0] SPI MISO SO EXT3 and EDBG

PB23 SERCOM5 PAD[3] SPI SCK SCK EXT3 and EDBG

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