The expansion board shown in Figure 4, the IO1 Xplained Pro, is designed to help developers understand the most important peripheral blocks of the microcontroller. It includes an LED, a light sensor, a low-pass filter to allow testing of the PWM and ADC blocks, a 12-bit temperature sensor with 8 kB of EEPROM connected over an I2C bus, and a microSD card socket, connected over an SPI bus. A microSD card is included with the board. A couple of spare pins are also brought out.

Figure 4: Universal expansion board for testing and training.
Atmel I01 Xplained

If you wish to output something to a display, you can use the OLED1 Xplained Pro expansion board. The board is fitted with a 128-by-32 pixel OLED display with an SPI interface. The board also provides three LEDs and three buttons. This board is designed to be connected to header EXT3.

A special feature of the SAM D20, like certain other microcontrollers by the same manufacturer, is the PTC. Atmel offers a kit called the QT1 Xplained Pro comprising two expansion boards. Externally the two boards appear identical, but they use different touch detection technologies: ‘QTouch self capacitance’ and ‘QTouch mutual capacitance’. We will examine the exact differences between these technologies and their advantages and disadvantages in a later installment of this series. Each board includes a touch wheel, a slider and two buttons, as well as ten yellow LEDs and one RGB LED.

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