1646

© 2012 Microchip Technology Incorporated. All Rights Reserved. 1646 USB7 Slide 1

1646 USB7

USB Embedded Host and On-The-Go (OTG)


Objectives

To know what host enabled options are available

To understand how they are different and when they should be selected over another

Get hands-on experience on several of the available USB host class drivers

To know where to go next to get more information, tools, training, etc., to get a design going


Agenda

What’s Available? OTG vs Embedded Host vs Dual Role

Host and OTG stack architecture overview

Mass Storage Host Lab 1

Human Interface Device Lab 2

Communication Device Class Lab 3

OTG in more detail


WHAT’S AVAILABLE


Embedded Host

Always a host, never a USB device

Standard A connector

Must always supply power

Example: Data Logger


On-The-Go (OTG)

Mobile, simple hosts

Want to be host sometimes but device sometimes

Power consumption

Micro A/B connector

Example: Smart Phones or Tablets


Dual Role (multi-connector devices)

2 connectors – must only have one accessible at any point of time

Wants to be either embedded host or USB device, but doesn’t need to dynamically switch

Some electrical considerations

Example: Data Logger with field update via PC


HOST AND OTG STACK OVERVIEW


High Level Software Architecture

Host

Class

Drivers

User Code

Hardware



Host

User Code

US

BH

ostInitia

lize()

US

BH

ostT

asks()

US

B_

HO

ST

_A

PP

_E

VE

NT

_H

AN

DL

ER

()

US

B_H

OS

T_A

PP

_D

AT

A_E

VE

NT

_H

AN

DLE

R()


USBHostTasks()

Keeps the USB host state machine going

Needs to be called periodically

Needed for transfers to complete

Affects throughput

Needed for notifications of events

Attach, detach, etc.


USB_HOST_APP_EVENT_HANDLER()

Notification of most events occurring on the bus

Device attach

Device detach

Transfer complete

Errors

Is called from USBHostTasks()


USB_HOST_APP_DATA_EVENT_HANDLER()

Notification of time critical events on the bus

Timer interrupts


Host/Client Driver Interface

Host

Class

Drivers

usb_config.c

usb_config.h

<D

river>

Even

t()

<D

river>

Da

taE

ven

t()

Tra

nsm

it F

un

ction

s:

US

BH

ostW

rite

()

US

BH

ostR

ea

d()

US

BH

ostIsR

ead

Co

mple

te()

Etc

.


usb_config.c/usb_config.h

Used for stack configuration

Used for host, device, and OTG configuration

Contains build options and data tables required for USB stack operation


Targeted Peripheral List (TPL)

List of supported devices for that embedded host and OTG Devices not on that list will not be

able to enumerate

Specified by Vendor ID(VID) and Product ID(PID)

pair

Or Class, Subclass, and Protocol set


TPL – Implementation Located in usb_config.c USB_TPL usbTPL[NUM_TPL_ENTRIES] =

{

/*[1] Device identification information

[2] Initial USB configuration to use

[3] Client driver table entry

[4] Flags (HNP supported, client driver entry, SetConfiguration() commands allowed)

---------------------------------------------------------------------

[1] [2][3] [4]

---------------------------------------------------------------------*/

{ INIT_CL_SC_P( 8ul, 6ul, 0x50ul ), 0, 0, {TPL_CLASS_DRV} } // SCSI - most MSD drives

{ INIT_VID_PID( 0x18D1ul, 0x2D00ul ), 0, 1, {0} }, // This specific device (Android)

}

CLIENT_DRIVER_TABLE usbClientDrvTable[NUM_CLIENT_DRIVER_ENTRIES] =

{

{

USBHostMSDEventHandler,

NULL,

0

},

{

AndroidAppEventHandler,

AndroidAppDataEventHandler,

ANDROID_INIT_FLAG_BYPASS_PROTOCOL

}

};


MASS STORAGE DEVICE CLASS (MSD) HOST


What is MSD?

Used to talk to memory devices

Thumb drives

USB hard drives


MSD Host Driver Architecture

MSD SCSI Transport

MSD

USB Host

File System Layer (FAT/FAT32)

FS

fopen()

FS

fclo

se()

FS

fread()

FS

fwrite

()

US

BH

ostM

SD

SC

SIM

edia

Dete

ct(

)

FS

Init()

US

BH

ostM

SD

Tasks()



MSD

MSD SCSI Transport

USB Host


Se

cto

rRe

ad()

Se

cto

rWrite

()

Me

dia

Initia

lize

()

USBHostMSDSCSI…

Me

dia

De

tect(

)



MSD

MSD SCSI Transport

USB Host


Tra

nsfe

r()

Tra

nsfe

rIsC

om

ple

te()

Initia

lize

()

USBHostMSD…



MSD

MSD SCSI Transport

USB Host


Rea

d()

Tra

nsfe

rIsC

om

ple

te()

Write

()

USBHost…


Microchip Disk Drive (MDD) Overview

MSD

MSD SCSI Transport

USB Host


MDD/FAT library used to talk to drives Supports FAT12/FAT16/FAT32

Supports long file names and several character encodings

Currently only supports a single drive only one type

only one at a time

Uses POSIX style interface FSfopen()

FSfclose()

FSfread(), FSfwrite()


The FSInit Function

Initializes data structures

Loads device information from the MBR and Boot Sector

Initializes Media

Prototype:

int FSInit (void);

Returns: TRUE if initialization is successful FALSE otherwise


The FSfopen Function

Loads file information or creates a new file

Prototype:

FSFILE * FSfopen (const char * fileName, const char * mode);

Arguments fileName: The name of the file to open Mode: FS_READ, FS_WRITE, FS_APPEND, or –PLUS modes

Returns: A pointer to the initialized file object on success NULL on failure

Can also be used to open directories

Example

FSFILE * pointer;

pointer = FSfopen (“FILE.TXT”, “w+”); // Or use WRITEPLUS macro

if (pointer == NULL)

// Error


The FSfwrite Function

This function will write ‘n’ items of ‘size’ bytes from the structure pointed to by ‘ptr’ to the file pointed to by ‘stream’

Prototype:

size_t FSfwrite (const void * ptr, size_t size, size_t n, FSFILE * stream);

Arguments: ptr: A pointer to the data to be written size: The size of the objects to write n: The number of objects to write stream: The file the data will be written to

Returns: The number of objects written


The FSfclose Function

Updates information in the root and FAT

Frees the memory used by the FSFILE object

Prototype:

int FSfclose (FSFILE * fo);

Argument: A pointer to the file to close

Returns: 0 if the file was closed successfully EOF (-1) otherwise

Example

FSFILE * pointer;

pointer = FSfopen (“FILE.TXT”, “w”);

if ( FSfclose (pointer) != 0)

// Error


LAB 1 Mass Storage Host (MSD)


Lab 1 Objectives

Write file to drive

Lab manual can be found at

C:\Masters\1646 USB7\manual.pdf

Open MPLAB® X IDE,

Select “File->Open Project”

Select the “c:\Masters\1646 USB7\lab1_msd\MPLAB.X” file.

Solutions are both in the lab manual and in the “C:\Masters\1646 USB7” folder


Lab 1 Summary

How to write a file on a USB thumb drive


HUMAN INTERFACE DEVICE CLASS (HID) HOST


What is the Human Interface Device Class (HID)?

Typically used for input devices

Keyboards, mice, barcode scanners, touch digitizers, game controllers, etc.

Sometimes used for other custom devices that don’t need large amounts of throughput


Reports

HID Devices transfer what are known as reports

Standardizes the data values for each type of input event

Allows designer to select which features are implemented or not


Reports

Report ID

L

X shift

Y shift

R

Report ID

L

X shift

Y shift

R

Report ID

R

X shift

Y shift

L

A B C D E F G H

I J K M N O

Q

P

T S

Right Click Occurred


HID Host Driver Architecture

HID Host

USB Host

Report Parser

HID Keyboard Driver HID Mouse Driver

USB_HOST_APP_EVENT_HANDLER (

EVENT_HOST_HID_KEYBOARD_ATTACHED,

EVENT_HOST_HID_KEYBOARD_DETACHED,

EVENT_HOST_HID_KEYBOARD_KEY_PRESSED,

EVENT_HOST_HID_KEYBOARD_KEY_RELEASED

)


EVENT_HOST_HID_KEYBOARD_ATTACHED

Signals when a new keyboard is attached

*data is the handle of the attached keyboard Useful for getting information about the attached

keyboard

Used to identify which keyboard is sending a given message


EVENT_HOST_HID_KEYBOARD_DETACHED

Signals when a keyboard is detached

*data is the handle of the detached keyboard


EVENT_HOST_HID_KEYBOARD_KEY_PRESSED EVENT_HOST_HID_KEYBOARD_KEY_RELEASED

*data is a EVENT_HOST_HID_KEYBOARD_KEY_EVENT_DATA* typedef struct

{

USB_HID_KEYBOARD_KEYS key;

void* keyboard;

} EVENT_HOST_HID_KEYBOARD_KEY_EVENT_DATA;

Provides the HID key pressed and the handle for the associated keyboard.


LAB 2 Human Interface Device Class (HID)


Lab 2 Objectives

Create code to talk to a HID class device

Get the information from a USB keyboard when a key is pressed


Lab 2 Summary

Read information from a USB keyboard


COMMUNICATION DEVICE CLASS (CDC) HOST


What is the Communication Device Class (CDC)

Used for communication devices

USB modems

Some cell phones

Cable modems

USB Wi-Fi® dongles

USB to Serial cables


CDC Host API

CDC Host

USB Host

US

BH

ost_

CD

C_

AC

M_

Write

()

US

BH

ost_

CD

C_

AC

M_

Re

ad

()

US

BH

ost_

CD

C_

AC

M_

Write

Sta

tus()

US

BH

ost_

CD

C_

AC

M_

Po

rtS

tatu

sG

et(

)

US

BH

ost_

CD

C_

AC

M_

Re

ad

Sta

tus()

US

BH

ost_

CD

C_

AC

M_

Po

rtD

ete

ct(

)


USBHost_CDC_ACM_PortDetect()

Detects new CDC ports available and returns handles to those ports for access by the application

Prototype:

void* USBHost_CDC_ACM_PortDetect(void);

Arguments None

Returns: void* - handle to the detected CDC port. NULL if no port detected

void* device = NULL;

while(1)

{

USBTasks();

if(device == NULL)

{

device = USBHost_CDC_ACM_PortDetect();

continue;

}

Example


USBHost_CDC_ACM_PortStatusGet()

Determines the status of a specified CDC device

Prototype:

USB_CDC_ACM_DEVICE_STATUS

USBHost_CDC_ACM_PortStatusGet(void* handle);

Arguments void* handle – the handle of the device that you are checking the

status of.

Returns: USB_HOST_CDC_ACM_STATUS__UNKNOWN_DEVICE USB_HOST_CDC_ASCM_STATUS__DEVICE_READY


USBHost_CDC_ACM_PortStatusGet()

void* device = NULL;

while(1)

{

USBTasks();

if(device == NULL)

{

device = USBHost_CDC_ACM_PortDetect();

continue;

}

switch(USBHost_CDC_ACM_PortStatusGet(device))

{

case USB_HOST_CDC_ACM_STATUS__DEVICE_READY:

break;

case USB_HOST_CDC_ACM_STATUS__UNKNOWN_DEVICE:

device = NULL;

continue;

default:

continue;

}

//… do something meaningful with the CDC device here…

Example


USBHost_CDC_ACM_Write()

Writes data to a CDC device

Prototype:

USB_CDC_ACM_RETURN_CODE USBHost_CDC_ACM_Write(

void* handle,

BYTE* data,

DWORD size);

Arguments void* handle – handle of the device to write to BYTE* data – the data that needs to be written DWORD size – the amount of data to send

Returns: USB_CDC_ACM_RETURN_CODE

USB_SUCCESS USB_BUSY USB_UNKNOWN_DEVICE USB_<various error codes>


USBHost_CDC_ACM_WriteStatus()

Writes data to a CDC device

Prototype:

USB_CDC_ACM_RETURN_CODE USBHost_CDC_ACM_WriteStatus(

void* handle,

DWORD *size);

Arguments void* handle – handle of the device to check DWORD *size – pointer to a DWORD where the actual amount of

data written will be stored

Returns: USB_CDC_ACM_RETURN_CODE

USB_SUCCESS USB_BUSY USB_UNKNOWN_DEVICE USB_<various error codes>


USBHost_CDC_ACM_WriteStatus()

BYTE TxData[2];

DWORD size;

//... Do all of the device detection...

if(USBHost_CDC_ACM_WriteStatus(device, &size) != USB_BUSY)

{

TxData[0] = 'H';

TxData[1] = 'i';

USBHost_CDC_ACM_Write(device, TxData, 2);

}

Example


USBHost_CDC_ACM_Read() USBHost_CDC_ACM_ReadStatus()

Identical to Write() and WriteStatus() expect that they read instead…

Note: The ReadStatus() function return USB_SUCCESS when either: The request amount of data is received A transfer is completed (i.e. - you requested 100 bytes but the

transfer was only 2 bytes)


CDC Events

USB_EVENT_CDC_ACM_DEVICE_ATTACH data = handle of the device attached

USB_EVENT_CDC_ACM_DEVICE_DETACH data = handle of the device that detached

USB_EVENT_CDC_ACM_READ_COMPLETE data = handle of the device that completed read. Use

ReadStatus() to get the amount of data

USB_EVENT_CDC_ACM_WRITE_COMPLETE

data = handle of the device that completed write. Use WriteStatus() to get the amount of data


LAB 3 Communication Device Class (CDC)


Lab 3 Objectives

Establish communication with a serial device using a USB to Serial converter cable

Test sending and receiving data


Lab 3 Summary

Created a connection to a USB to UART conversion cable


PIC24, dsPIC® DSC,

or PIC32MX

with the USB OTG

module

Full size A

Receptacle

Embedded Host Example Circuit

VBUS

D+

D-

GND

5v

PPTC

A/D

D+

D-

VUSB

2KΩ

2KΩ

150μF

.1μF

3.3v


Certification Considerations Embedded Host

Checklists Systems

No Silent Failures Hub error message

Device not supported message

Power Over-current notification

Resettable overcurrent protection

Drop voltage

TPL


OTG IN DETAIL



OTG Controls Host Device

Function

Drivers

Class

Drivers

User Code

Hardware


Device Types

A – Device

Device plugged into the A side of a cable. Starts out as the host

B – Device

Device plugged into the B side of a cable. Starts out as a peripheral


New 5th Pin

Old connectors had 4 pins on the receptacle that were used: VBUS, GND, D+, and D-

OTG connectors have 5 pins on the receptacle that are used: VBUS, GND, D+, D-, and ID ID pin is used to determine which side of

the cable is the A (host) side ID should be pulled high through a

resistor Built into PIC24F and PIC32MX devices

with USB OTG


Mechanical

Micro A/B Receptacle

Pin 1: VBus

Pin 2: D-

Pin 3: D+

Pin 4: ID

Pin 5: GND

Pin 1


Mechanical

Micro B Receptacle

Pin 1: VBus

Pin 2: D-

Pin 3: D+

Pin 4: ID

Pin 5: GND

Pin 1


Mechanical

Micro A Plug

Pin 1: VBus

Pin 2: D-

Pin 3: D+

Pin 4: GND (ID)

Pin 5: GND

Pin 1


Mechanical

Micro B Plug

Pin 1: VBus

Pin 2: D-

Pin 3: D+

Pin 4: Floating (ID)

Pin 5: GND

Pin 1


OTG Cable Example

Micro

A Plug Micro

A/B

Host Peripheral

Micro

B Plug Micro

A/B


OTG Cable Example

Micro

A Plug Micro

A/B

Host Peripheral

Micro

B Plug Micro

B


OTG Cable Example

Micro

A/B

Peripheral DOESN’T FIT!!

Micro

B

Micro

A Plug

Micro

B Plug


Mechanical

Cables

Allowable Types

Micro-A plug to Micro-B plug

Micro-A plug to Standard-A receptacle

Micro-B plug to Standard-A plug

Captive cable with Micro-A plug

Length

2 meters or less (different from USB-v2.0 limit of 5 meters)


OTG Descriptor

Returned in the GetDescriptor(Configuration) request

Required only if B-Device supports any OTG specific features

Tells the host (A-Device) what the B-Device is capable of


OTG Descriptor

Offset Field Size Value Description

0 bLength 1 Number Size of Descriptor (3 for v1.3 or earlier, 5 for v2.0)

1 bDescriptorType 1 Constant OTG type = 9

2 bmAttributes 1 Bitmap Attribute Fields

D7-D3: reserved

D2: ADP supported

D1: HNP supported

D0: SRP supported

3 bcdOTG 2 OTG Binary coded decimal revision number that the device is compliant to (0200H for example)


Host Negotiation Protocol (HNP)

Allows two connected OTG devices to exchange roles

A-device still provides the power

Roles stay swapped until bus goes idle


Session Request Protocol (SRP)

OTG allows host to power down bus when not in use

SRP provides a way for a device to signal to a power down host that it wants to talk


Attach Detection Protocol (ADP)

OTG allows host to power down bus when not in use

Determine if a device has detached while the bus is powered down


OTG Acceptance

OTG acceptance is currently very low

Nearly impossible to find cables

Certified connectors are easier, but not a wide range of selection

Nearly impossible to find real products


Certification Considerations OTG

Checklists OTG Peripheral Systems

SRP

HNP

TPL

Power restrictions Unconfigured power


OTG Example Circuit

PIC24F or PIC32MX

USB device

Micro A/B

Receptacle

VBUS

D+

D-

GND

VBUS

D+

D-

VUSB

ID

GPIO

GPIO

USBID

Vdd .1 μF

MCP1253

PGOOD

SELECT

3.3v

VOUT

VIN nSHDN

GND

10 μF

3.3v

4.7 μF

C+

C-

1 μF


OTG vs. Embedded Host

OTG Embedded Host OTG Protocols (SRP, HNP, ADP)

Some are required Optional (or not possible)

Mechanical Micro A/B receptacle

2m max cable

A receptacle

5m max cable

Electrical 1.0μF < CDRD_VBUS < 6.5μF

8mA min to connected peripheral device (if A-device)

CHST_VBUS > 120μF

100mA min to connected peripheral


GETTING STARTED Where to go for more information


Software Examples Available

Embedded Host Data logging to a thumb drive

MCHPUSB host – temperature, pot reader

HID Host – talking to a keyboard

HID Host – talking to a mouse

Printer Host (PCL5 and PostScript)

CDC Host – hosting a serial to USB converter

Simple USB Charger

Simple demo writing to a thumb drive

Bootloading from a thumb drive


Software Examples Available

OTG

MCHPUSB OTG (We currently support only v1.3 of the OTG specification)

All software available, free download from:

www.microchip.com/usb


Demo Tools Available

Development Kit Explorer 16 (DV164033)

PIC24FJ64GB004 USB PIM (MA240019) PIC24FJ256GB110 USB PIM (MA240014) PIC32MX USB PIM (MA320002)

USB PICtail™ Plus Daughter Card (AC164131)


Demo Tools Available

Starter Kits

PIC24F Starter Kit (DM240011)

PIC32MX USB Starter Board (DM320003)


Microchip Regional Training Centers (RTCs)

Worldwide network of training facilities

Product, Tools and Applications-orientated classes (Ethernet, USB, Motor Control, etc..)

Flexible ☼ Most classes are half or one day duration

☼ Easily modified to fit a specific customer need

Cost Effective ☼ Most classes are $49 or $99 (US)

☼ Significant discounts on development tools used in the class

☼ Many centers reduce travel expenses


RTC Training Curriculum

New to Microchip MPLAB® Tool

Basics TLS0103

New to PIC18

New to PIC24

New to USB

PIC18 Arch.

MCU2101

PIC18 Peri.

MCU2121

16-bit Arch.

MCU3101

16-bit Peri.

MCU3121

Intro USB

COM3101

USB Device Ap.

USB Emb. Host

USB Device

COM3201

USB Host

COM3202


Summary

Today we covered: What host options are available

How they are different

Got hands on experience Writing to a thumb drive

Getting information from a keyboard

Using a CDC serial converter

Available development resources


The End

Questions?

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Enjoy the rest of your classes!


Trademarks

The Microchip name and logo, the Microchip logo, dsPIC, KeeLoq, KeeLoq logo, MPLAB, PIC,

PICmicro, PICSTART, PIC32 logo, rfPIC and UNI/O are registered trademarks of Microchip

Technology Incorporated in the U.S.A. and other countries.

FilterLab, Hampshire, HI-TECH C, Linear Active Thermistor, MXDEV, MXLAB, SEEVAL and

The Embedded Control Solutions Company are registered trademarks of Microchip Technology

Incorporated in the U.S.A.

Analog-for-the-Digital Age, Application Maestro, chipKIT, chipKIT logo, CodeGuard, dsPICDEM,

dsPICDEM.net, dsPICworks, dsSPEAK, ECAN, ECONOMONITOR, FanSense, HI-TIDE,

In-Circuit Serial Programming, ICSP, Mindi, MiWi, MPASM, MPLAB Certified logo, MPLIB,

MPLINK, mTouch, Omniscient Code Generation, PICC, PICC-18, PICDEM, PICDEM.net,

PICkit, PICtail, REAL ICE, rfLAB, Select Mode, Total Endurance, TSHARC, UniWinDriver,

WiperLock and ZENA are trademarks of Microchip Technology Incorporated in the U.S.A. and

other countries.

SQTP is a service mark of Microchip Technology Incorporated in the U.S.A.

All other trademarks mentioned herein are property of their respective companies.

© 2012, Microchip Technology Incorporated, All Rights Reserved.


OTG Appendix

Below is additional material for those interested to know more about how OTG works.