# Using ATSAMD21 SERCOM for more SPI, I2C and Serial ports ## Overview ![](https://cdn-learn.adafruit.com/assets/assets/000/029/964/medium800/arduino_atsamd.jpg?1453590786) If you've been using AVR's for a bit, particularly the Arduino UNO's ATmega328, you have likely bumped into the limits of having a single SPI, Wire (i2c) and UART (Serial) port. You can update to the Arduino MEGA, that'll give you some more UARTs, but you're still stuck with a single SPI and I2C port. ![](https://cdn-learn.adafruit.com/assets/assets/000/029/965/medium800/arduino_ports.png?1453590862) When we first checked out the ATSAMD21 chip (the processor used in the Arduino Zero and Adafruit Feather M0), we were very happy to see that the chip has 6 "SERCOM"s, a.k.a SERial COMmunication modules. Each one of these modules can be used for I2C, SPI or Serial. That means you can have 3 UART's & 3 SPI's, or maybe 2 SPI's and 4 I2C's. Basically, you have a ton of options for adding more hardware support for the most common 3 chip-to-chip protocols. ![](https://cdn-learn.adafruit.com/assets/assets/000/029/967/medium800/arduino_ds.png?1453591349) Now, the default Arduino IDE setup for the Zero/ATSAMD21 still only comes with one UART, one SPI and one I2C device, in the 'classic' locations ![](https://cdn-learn.adafruit.com/assets/assets/000/029/968/medium800/arduino_2843-04.jpg?1453592073) ...but that still leaves you with 3 full SERCOM's to do whatever you like! - [Next Page](https://learn.adafruit.com/using-atsamd21-sercom-to-add-more-spi-i2c-serial-ports/muxing-it-up.md) ## Featured Products ### Arduino Zero - 32 bit Cortex M0 Arduino with Debug Interface [Arduino Zero - 32 bit Cortex M0 Arduino with Debug Interface](https://www.adafruit.com/product/2843) With the new **Arduino Zero** , the more creative individual will have the potential to create one’s most imaginative and new ideas for IoT devices, wearable technologies, high tech automation, wild robotics and other not yet thinkable adventures in the world of... No Longer Stocked [Buy Now](https://www.adafruit.com/product/2843) [Related Guides to the Product](https://learn.adafruit.com/products/2843/guides) ### Adafruit Feather M0 Basic Proto - ATSAMD21 Cortex M0 [Adafruit Feather M0 Basic Proto - ATSAMD21 Cortex M0](https://www.adafruit.com/product/2772) Feather is the new development board from Adafruit, and like its namesake it is thin, light, and lets you fly! We designed Feather to be a new standard for portable microcontroller cores. This is the  **Feather M0 Basic Proto** , it has a bunch of prototyping space... In Stock [Buy Now](https://www.adafruit.com/product/2772) [Related Guides to the Product](https://learn.adafruit.com/products/2772/guides) ### Adafruit Feather M0 Adalogger [Adafruit Feather M0 Adalogger](https://www.adafruit.com/product/2796) Feather is the new development board from Adafruit, and like its namesake it is thin, light, and lets you fly! We designed Feather to be a new standard for portable microcontroller cores. This is the  **Adafruit Feather M0 Adalogger**  - our take on an... In Stock [Buy Now](https://www.adafruit.com/product/2796) [Related Guides to the Product](https://learn.adafruit.com/products/2796/guides) ### Adafruit Feather M0 Bluefruit LE [Adafruit Feather M0 Bluefruit LE](https://www.adafruit.com/product/2995) Feather is the new development board from Adafruit, and like its namesake, it is thin, light, and lets you fly! We designed Feather to be a new standard for portable microcontroller cores. This is the  **Adafruit Feather M0 Bluefruit LE**  - our take on an... In Stock [Buy Now](https://www.adafruit.com/product/2995) [Related Guides to the Product](https://learn.adafruit.com/products/2995/guides) ### Adafruit Feather M0 WiFi - ATSAMD21 + ATWINC1500 [Adafruit Feather M0 WiFi - ATSAMD21 + ATWINC1500](https://www.adafruit.com/product/3010) Feather is the new development board from Adafruit, and like its namesake it is thin, light, and lets you fly! We designed Feather to be a new standard for portable microcontroller cores. This is the  **Adafruit Feather M0 WiFi w/ATWINC1500** - our take on an... In Stock [Buy Now](https://www.adafruit.com/product/3010) [Related Guides to the Product](https://learn.adafruit.com/products/3010/guides) ## Related Guides - [Adafruit Feather M0 Adalogger](https://learn.adafruit.com/adafruit-feather-m0-adalogger.md) - [Adafruit Feather M0 Bluefruit LE](https://learn.adafruit.com/adafruit-feather-m0-bluefruit-le.md) - [CircuitPython Hardware: LED Backpacks & FeatherWings](https://learn.adafruit.com/micropython-hardware-led-backpacks-and-featherwings.md) - [CircuitPython Basics: Analog Inputs & Outputs](https://learn.adafruit.com/circuitpython-basics-analog-inputs-and-outputs.md) - [Adafruit NeoPXL8 FeatherWing and Library](https://learn.adafruit.com/adafruit-neopxl8-featherwing-and-library.md) - [3D Printed IoT On Air Sign for Twitch](https://learn.adafruit.com/3d-printed-iot-on-air-sign-for-twitch.md) - [Coffee Detonator: The TNT Plunger Grinder](https://learn.adafruit.com/coffee-detonator.md) - [Festive Feather Holiday Lights](https://learn.adafruit.com/festive-feather-holiday-lights.md) - [CircuitPython Hardware: ILI9341 TFT & FeatherWing](https://learn.adafruit.com/micropython-hardware-ili9341-tft-and-featherwing.md) - [CircuitPython Hardware: SSD1306 OLED Display](https://learn.adafruit.com/micropython-hardware-ssd1306-oled-display.md) - [7 Segment Display Internet Clock](https://learn.adafruit.com/7-segment-display-internet-clock.md) - [Adafruit BMP388 and BMP390 - Precision Barometric Pressure and Altimeter](https://learn.adafruit.com/adafruit-bmp388-bmp390-bmp3xx.md) - [Debug Header for the Feather [M0]](https://learn.adafruit.com/make-a-simple-debugging-featherwing-for-the-m0.md) - [MicroPython Basics: How to Load MicroPython on a Board](https://learn.adafruit.com/micropython-basics-how-to-load-micropython-on-a-board.md) - [All the Internet of Things - Episode Four: Adafruit IO](https://learn.adafruit.com/all-the-internet-of-things-episode-four-adafruit-io.md) - [Using Servos With CircuitPython and Arduino](https://learn.adafruit.com/using-servos-with-circuitpython.md) - [Using Bluefruit BLE to Give Disabled Users Switch Control Access to IOS Devices](https://learn.adafruit.com/ios-switch-control-using-ble.md)