Introduction

Late last year Avnet released the Avnet Azure Sphere Starter Kit Rev 2.  This blog will discuss the changes between the Rev 1 and Rev 2 boards, how to select the device in your build environment and what use cases are unlocked with the Rev 2 kit.

 

Where to Buy a Rev 2 board

The Avnet Azure Sphere Starter Kit Rev 2 can be purchased here.

 

Rev 2 Documentation

Complete Azure Sphere Starter Kit (Rev 1 and Rev 2) documentation can be found on our Element14 community web site here.

 

Physical Changes

These graphics identify all the different locations on the board for expansion connectors, buttons, LEDs, sensors and so on.  If you are familiar with the Rev 1 board you may notice the following physical changes . . .

 

  • The OLED Display (unpopulated) header was moved from the edge of the board to the center of the board and rotated 90 degrees
  • The M4 debug UART TX header was moved from the center of the board to the edge of the board
    • The M4 debug UART header now contains two GND signals, one for each M4 core
  • The (unpopulated) external power header only has a +5V connection, the +VBAT connection was removed from this location
  • A (unpopulated) CR2032 battery holder footprint was added to the bottom of the board to supply the +5VBAT power

 

A Rev 2 board with the OLED soldered to the new location in a 3D printed case

 

 

Block Diagram

 

 

How to identify which Revision you have

The Rev 2 board is marked as such.  Look for the silkscreened text under the Avnet Azure Sphere Module

 

 

Changes between Rev 1 and Rev 2

There were quite a few enhancements/features added between Rev1 and Rev 2.  For the nitty gritty details, please reference the Hardware User Guide, all the changes are documented there in great detail.  You can find the Hardware User Guide here. (Select the "Technical Documents" tab, then scroll down to the "Azure Sphere MT3620 Starter Kit - V2" section)

 

 

CategoryEnhancement or New Feature
Use case enhancements (Click sockets)
  • ISU0 (SPI/UART) is dedicated to Click socket #1
    • Supports using the ENC286J60 SPI interface via ISU0 and GPIO5
    • Supports the ETH Click board
  • ISU1 (UART/SPI) is dedicated to Click socket #2
  • ISU2 (I2C) is shared by both Click sockets and all I2C peripherals on the PCB
Use case enhancements (Pmod connector)
  • Default configuration supports type 4A UART (TX, RX, CTS, RTS)
  • Pmod connector can be reconfigured for type 2A SPI (set via zero-ohm resistors)
  • Avnet BLE Pmod add on board supported
Use case enhancements (Grove connector)
  • Default configuration supports Grove I2C interface
  • Grove connector can be reconfigured to support two wire UART interface (TX, RX) (set vis zero-ohm resistors)
Sphere module enhancements
  • Updated Avnet Azure Sphere Module Rev 2 is used on the board
    • Additional ISU2 pins available to support SPI and UART use cases
    • Pull up resistor change ensures that Power down mode can be entered
Power Supply robustness enhancements
  • MP5017 device replaces MP5018
    • Allows for additional margin for voltage drop across some USB cables/connectors
  • MPM3632 device replaces MPM3822
  • Additional improvements to ensure power input quality and protection
Wi-Fi LED GPIO reassignment
  • GPIO0 now drives LED4 (Wi-Fi LED)
  • Replaces GPIO5 that is required to support ethernet board configuration file on Click socket #1
VBAT changes
  • HW implementation now matches Microsoft's revised VBAT selection circuit
  • Option to add Lithium CR2032 coin-cell battery holder to bottom of board
OLED display moved to center of PCB
  • The optional OLED header was relocated to the center of the PCB
M4 UART headers moved to edge of PCB
  • Header pins for dedicated M4 core UART outputs are now easier to access at the edge of the PCB

 

 

Resistor Selectable Interface Changes

The Rev 2 board also allows for hardware configuration changes by relocating zero-ohm resistors.

 

Note: The zero-ohm resistors are 0402 sized SMD resistors (1mm x 0.5 mm), these will be difficult to change without proper equipment.

 

These optional configurations can extend the Starter Kit's uses cases by . . . .

  • Allowing the Azure Sphere applications to utilize 3 UARTS
  • Allowing the Azure Sphere applications to utilize two sperate SPI buses

 

Click Socket #2 Configuration Option

Click Socket #2 can be reconfigured from a UART configuration to a SPI configuration.  See the Hardware User Guide for details.

  • Depopulate R59 and R60
  • Populate R61 and R62

 

PMOD Configuration Option

The (unpopulated) PMOD connector can be reconfigured from a UART configuration to a SPI configuration.  See the Hardware User Guide for details.

  • Depopulate R39 and R50
  • Populate R41 and R52

 

Grove Connector

The Grove connector can be reconfigured from a I2C configuration to a  2-wire UART configuration.  See the Hardware User Guide for details.

  • NOTE: When the Grove connector is configured for UART operations, the ISU2 I2C interface will be inoperable.
    • This alternate configuration will disable ISU2 I2C functionality present on both click sockets, the Grove connector, the OLED header and the on-board sensors
  • Depopulate R57, R53 and R55
  • Populate R54 and R56

 

New use cases unlocked with the Rev 2 kit

What are some of the additional use cases that are unlocked when you use the Rev 2 kit?

  • Wired Ethernet using a ETH Click board in Click socket #1
  • Click boards that use type 4A UARTS are now supported in Click socket #2
  • Additional UARTs when optional hardware configurations are selected by relocating the zero-ohm resistors
    • The ability to use UART Grove devices
  • Access to a second SPI ISU configurations by relocating the zero-ohm resistors
    • Click Socket #1
    • PMOD connector

 

Selecting the Rev 2 kit in your Azure Sphere Development Environment

Avnet has worked with Microsoft to include Rev 2 hardware definition files in both the most recent Azure Sphere SDK and the Microsoft Azure Sphere Example Repo.

 

As with any Azure Sphere hardware platform, select the kit you're using for your application in the CMakeLists.txt file.

 

  • For the Avnet Azure Sphere Starter Kit Rev 1 select the TARGET_DIRECTORY: /HardwareDefinitions/avnet_mt3620_sk
  • For the Avnet Azure Sphere Starter Kit Rev 2 select the TARGET_DIRECTORY:  /HardwareDefinitions/avnet_mt3620_sk_rev2

 

Additional Azure Sphere Resources

 

Conclusion

We're very happy with the new functionality enabled by the Rev 2 kit.  Please post any comments or questions you have in the comments section below.

 

Thanks for reading!