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Azure Sphere - Tips to max-out your Starter Kit hardware! (Part 1)

peterfenn

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Avnet Starter Kit use of MT3620 ISUs (serial interface blocks)

 

The three ISUs accessible on your Starter Kit are "preconfigured" in that the ISU signals pinned-out of the module were limited for the support of:

  • ISU0: UART0 (4 IOs)
  • ISU1: SPI1 (5 IOs)
  • ISU2: I2C2 (2 IOs)

 

It is possible however within these pinout limitations, to assign the ISU functions as follows:

  • ISU0: use for I2C or UART or SPI
  • ISU1: use for I2C or UART or SPI
  • ISU2: use for I2C only

 

The table below shows in blue text the functions these ISUs are "assigned" to on the Starter Kit, followed by the alternative interfaces that can be supported by these pins

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The serial interface capabilities of the ISUs are documented at:

https://docs.microsoft.com/en-us/azure-sphere/hardware/mt3620-product-status

 

Starter Kit use of GPIOs

 

The table below shows in blue text the functions that other GPIOs have been assigned to on the Starter Kit

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Starter Kit unpopulated Expansion Connectors

 

Additional expansion options are accessible via three unpopulated connector sites on your Starter Kit (see green-colored call-outs in the board view above)

 

 

J11 3-pin header

This pins-out the TXD outputs of the MT3620's two M4-dedicated UARTs, typically for M4 application debugging (via a USB to serial cable)
but can alternatively be assigned for user-defined GPIO functions

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A good example where an M4-dedicated UART is used for console output (debugging info) for an application, is provided in the UART_RTApp_MT3620_BareMetal sample application from Microsoft
https://github.com/Azure/azure-sphere-samples/tree/master/Samples/UART/UART_RTApp_MT3620_BareMetal

In other real-time samples, the application polls when data is sent via the UART. In this application however memory buffers are used for send and receive of data, and interrupts rather than polling are used.

(This approach makes the UART_RTApp sample a useful starting-point for non-blocking applications)

 

 

J13 UART/BLE Connector

An unpopulated 2x6 connector site is located under Click Socket #2. Designed to accommodate a 2x6 right-angle female socket,
the pinout is compatible with a subset of Pmod peripheral boards available from Digilent and other suppliers

Notes:

  • The four (ISU0) UART pins and GPIO2 are shared with both Click sockets
  • GPIO1 and GPIO17 are shared only with Click socket #2
  • The WAKEUP input pin allows an external device to wake-up the MT3620 SoC
  • All signalling on this connector is at 3.3V levels

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Right-angle Pmod connector (viewed from board edge)

 

 

J7  OLED Display Connector

The pinout and corner mechanical mounting hole were designed to accommodate one of many 3rd-party 128x64 I2C OLED graphic displays

Make sure to select an OLED display with GND and VCC in the correct order! (Some low-cost OLED displays reverse the sequence of the GND and VCC pins!)

This connector site can alternatively be used for easy attachment of an external sensor to the I2C bus

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OLED Display Connector (viewed from above the board edge)

 

For more Information...

 

For detailed information on your Starter Kit's hardware capabilities, refer to the following documents:

     http://avnet.me/mt3620-datasheet

 

Take a look at the Avnet Azure Sphere Starter-Kit: Advanced Tutorial for a comprehensive application example that adds an inexpensive OLED display and Click relay board, and offers rapid implementation via a pre-engineered application template for Azure IoT Central dashboard, remote control of LEDs, relays and OLED messages, plus email notifications, etc

 

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Part 2 of this Tips to max-out your Starter Kit hardware! series is available here:

http://avnet.me/azphere-kit-tips-2