1. Introducing low-power buses for Windows 8
9/22/2018 2:03 PM
HW-251T
Introducing low-power buses for Windows 8
John Felkins
Program Manager
Microsoft Corporation
© 2010 Microsoft Corporation. All rights reserved. Microsoft, Windows, Windows Vista and other product names are or may be registered trademarks and/or trademarks in the U.S. and/or other countries.
The information herein is for informational purposes only and represents the current view of Microsoft Corporation as of the date of this presentation. Because Microsoft must respond to changing market conditions, it should not be interpreted to be a commitment on the part of Microsoft, and Microsoft cannot guarantee the accuracy of any information provided after the date of this presentation. MICROSOFT MAKES NO WARRANTIES, EXPRESS, IMPLIED OR STATUTORY, AS TO THE INFORMATION IN THIS PRESENTATION.

2. Agenda Why we need low-power buses
The new picture of system connectivity
Introducing each “new” bus
How to use low-power buses to integrate a sensor
You’ll leave with an example of how to
Write, integrate and test a simple sensor on I2C

3. Enable systems to reduce power consumption by using low-power peripheral buses.

4. Why Windows needs more buses

5. The inside today’s PC Standardized Buses PCI and USB
Fast, powerful, enumerable
Class drivers
Proprietary Buses
SMBus, LPC, etc
Proprietary uses
Proprietary drivers
Simple Buses
I2C, SPI, High speed UART, GPIO
Often require embedded controllers and special firmware

6. The bus connectivity challenge
Many system designs, many form factors
Peripherals may use several low power buses
Peripheral drivers should be portable, like they are on standardized buses
Enable power and cost savings

7. Our solution: You write your driver once, and we take care of the per-platform configurations.

8. One driver – two different tablets
demo
One driver – two different tablets

9. The New Picture of System Connectivity

10. Connectivity inside Windows 7 PCs
Graphics
System Chipset
PCI
Bluetooth
Camera
Touchscreen
USB
Embedded Controller
Sensors, buttons, lights, etc.
LPC/SMbus

11. Device connections with low-power buses
System Chipset
I2C 1
GPIO
I2C 2
UART
Accelerometer
Ambient Light Sensor
Touch Screen
Bluetooth Radio

12. Device enumeration in Windows 8
Accelerometer
Ambient Light Sensor
Touch Screen
Bluetooth Radio
I2C
I2C
UART
GPIO
IHV
SoC Vendor
ACPI
Microsoft
Firmware
Firmware

13. Connectivity with low-power buses
Accelerometer
Ambient Light Sensor
Touch Screen
Bluetooth Radio
Resource Hub
I2C
I2C
GPIO
UART
IHV
SoC Vendor
ACPI
Microsoft
Firmware
Firmware

14. Introducing each “new” bus

15. The “new” low power buses
GPIO
Used as interrupt or for general IO
Buttons, switches, lights, system wake, etc
Interrupts for SPB, serial, and other buses
SPB
I2C, SPI
Up to 3.4Mbps for I2C, 160Mbps for SPI
Wide variety of peripherals
Input
Radios
Sensors
Power management
Serial
High Speed UART
Up to 20Mbps
No COM ports
Typically used for Bluetooth, GPS, and other radios

16. The APIs for each bus GPIO I2C & SPI HSUART (Serial)
New READ PINS and WRITE PINS IOCTLs for IO Connections
Existing CONNECT and DISCONNECT interface for Interrupt Connections
I2C & SPI
Simple Peripheral Bus (SPB) Interface
Read, write, lock, unlock, sequence
HSUART (Serial)
Serial interface
No COM ports

17. How devices work on low power buses
The chipset vendor writes bus controller drivers for their platform
The peripheral driver writer drivers using the GPIO, SPB, Serial, and Interrupt APIs
The system builder connects the dots in ACPI
Windows helps with cross-driver dependencies, power, enumeration, reliability and more

18. Leading by example: how to integrate a sensor

19. SpbAccelerometer’s wiring diagram
System on Chip
I2C Controller
GPIO Controller
ADXL345 Accelerometer
I2C (addr 0x1d)
Interrupt

20. SpbAccelerometer’s driver stack
UMDF
Sensor Class Extension
SpbAccelerometer Driver
KMDF
Simple Peripheral Bus API
Windows Driver Interrupts
I2C Controller Driver (3rd Party)
GPIO Controller Driver (3rd party)
Sensor Hardware (I2C + GPIO)

21. Ingredients of SpbAccelerometer
User mode Sensor Driver
Implements the Sensor Class Extension to provide sensor data to Windows
Accesses SPB APIs to read/write data to the I2C bus
Uses a passive level GPIO user mode interrupt for detecting new motion data

22. ACPI description for SpbAccelerometer
Device(ACCL)  { Name (_HID, "SpbAccelerometer")  Name (_CID, "Sensor")  Name (_UID, 0)  Method(_CRS, 0x0, NotSerialized) { Name (RBUF, ResourceTemplate () { I2CSerialBus (AddressingMode7Bit, , 0x1D, ControllerInitiated, "\\_SB.I2C3", , ) GpioInt(ResourceConsumer, Level, ActiveHigh, Exclusive, 0, 0, "\\_SB.GPI1", ) {19} }) Return(RBUF) } }
I2C3, Address 0x1d, 400kHz
GPIO level interrupt on #19
© 2010 Microsoft Corporation. All rights reserved. Microsoft, Windows, Windows Vista and other product names are or may be registered trademarks and/or trademarks in the U.S. and/or other countries.
The information herein is for informational purposes only and represents the current view of Microsoft Corporation as of the date of this presentation. Because Microsoft must respond to changing market conditions, it should not be interpreted to be a commitment on the part of Microsoft, and Microsoft cannot guarantee the accuracy of any information provided after the date of this presentation. MICROSOFT MAKES NO WARRANTIES, EXPRESS, IMPLIED OR STATUTORY, AS TO THE INFORMATION IN THIS PRESENTATION.

23. What’s in the Windows Driver Kit (WDK)
SpbTestTool driver and app for I2C, SPI
SpbAccelerometer sample sensor driver on I2C
Bluetooth bus driver on UART
UART controller driver for PCs
SimDevice – a sample driver that consumes GPIO interrupt and IO resources

24. How to get started
Get I2C-capable hardware from one of our SoC partners
Install Windows and the WDK
Get the platform drivers (I2C, GPIO, SPI, HSUART, etc) from the platform provider
Attach your peripheral, and write the appropriate ACPI to describe the peripheral (this can programmed into firmware or into the registry)

25. How to get started
Use SpbTestTool (for SPI, I2C) to see if you can read/write data from your device
This validates the electrical connection and ACPI configuration for I2C/SPI
Follow one of our WDK samples to write your driver

26. Recap

27. Recap New low-power buses available for Windows 8
One driver, one part – let ACPI and Windows handle the plumbing
Everything you need to get started is in the Windows Driver Kit

28. Related sessions [HW-249T] Architecting and integrating sensor drivers
[HW-235T] Developing drivers in Visual Studio
[HW-255T] Integrating Bluetooth on low-power buses

29. Further reading and documentation
Developing, Testing, and Deploying Drivers
Windows Hardware Dev Center
Windows Dev Center
Contact info –

30. thank you Feedback and questions http://forums.dev.windows.com
Session feedback

31. 9/22/2018 2:03 PM
© 2011 Microsoft Corporation. All rights reserved. Microsoft, Windows, Windows Vista and other product names are or may be registered trademarks and/or trademarks in the U.S. and/or other countries.
The information herein is for informational purposes only and represents the current view of Microsoft Corporation as of the date of this presentation. Because Microsoft must respond to changing market conditions, it should not be interpreted to be a commitment on the part of Microsoft, and Microsoft cannot guarantee the accuracy of any information provided after the date of this presentation. MICROSOFT MAKES NO WARRANTIES, EXPRESS, IMPLIED OR STATUTORY, AS TO THE INFORMATION IN THIS PRESENTATION.
© 2011 Microsoft Corporation. All rights reserved. Microsoft, Windows, Windows Vista and other product names are or may be registered trademarks and/or trademarks in the U.S. and/or other countries.
The information herein is for informational purposes only and represents the current view of Microsoft Corporation as of the date of this presentation. Because Microsoft must respond to changing market conditions, it should not be interpreted to be a commitment on the part of Microsoft, and Microsoft cannot guarantee the accuracy of any information provided after the date of this presentation. MICROSOFT MAKES NO WARRANTIES, EXPRESS, IMPLIED OR STATUTORY, AS TO THE INFORMATION IN THIS PRESENTATION.