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Member Since: September 20, 2012

Country: United States

  • That’s an interesting observation.

    I don’t see why the board would not function without the external oscillator.

    I’m curious to know why SFE chose to go with an external 32.768kHz crystal on this board. The SAMD21 has two 32.768kHz internal oscillators–both a 32.768kHz High Accuracy and a 32.768kHz Ultra Low Power (in additional to several other full-speed internal oscillators). Perhaps may more accuracy?

  • Thanks mate! Very helpful.

  • Google “burning arduino bootloader using arduino” or check out the Arduino site http://arduino.cc/en/Tutorial/ArduinoISP for using Arduino as an ISP to burn a bootloader.

  • Yes as well as for all other AVR’s. From section 6.2.1 of the 328 datasheet listed above “The device is shipped with internal RC oscillator at 8.0MHz and with the fuse CKDIV8 pro- grammed, resulting in 1.0MHz system clock.”

    The MCU will run at ~1.0MHz by default, however the CKDIV8 fuse bit can be cleared to run the MCU at 8.0 MHz using only the internal RC oscillator. Also note that Atmel specifies the internal oscillator to fall with +- 10% accuracy so if you need to generate a very accurate clock signal (usually for UART transmission), an external crystal may be required.

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