Firmware for USB 2.0

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Firmware for USB 2.0

• Ryan AugustinNetchip Technology, Inc
• ryan_at_netchip.com

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Agenda

• USB 2.0 device-side programming
• New USB 2.0 features a programmers glossary
• Choosing a chip from a programmers perspective
• Performance fast transfers, race conditions
• Development aids
• Standard tools (USB analyzer)
• Manufacturers Tools and support
• Your Rev 1 board Tips, hints, steps to success

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USB 2.0 Glossary, Features For the Chip
Programmer

• Glossary
• CHIRP - Device/host Whos 2.0, whos 1.1?
• PING - Better way to NAK OUT packets
• Micro-frame - 8 micro-frames per frame
• ? -
• USB 2.0 features for chip programmers
• 480 Mbit/s - 40 times faster than USB 1.1
• Bulk/Int 512 - Bulk and Interrupt MaxPkt now 512
• ISO 1024 - ISO MaxPkt now 1024 (up to 3 per
  micro frame)

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USB 2.0 Max Packet Size
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Choosing a Chip Programmers Perspective

• Get involved choosing the chip
• Understand the hardware designers restrictions
• Understand your task
• Can the chip help you and the HW designer?
• Pitfalls e.g. The endianism problem
• Can the chip maker help?
• Development kits
• Support policy

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Choosing a Chip Transfers and Hardware

• Programmed I/O (Firmware transfer loop)
• Transfer Rate One pass of a for loop
• End conditions
• Packet level How much overhead?
• Transfer level ZLPs and dribble bytes
• Write samples (Surprise!)
• DMA
• End conditions
• Deep FIFOs
• The buzz
• Double depth (2 x 512 byte) minimum
• FIFO allotment

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Transfer Firmware Programmed I/O

• IN and OUT transfer firmware
• Interrupt handlers
• Arbitrary length transfers (zero to a zillion1)
• Fast! (any type Iso, Bulk, Interrupt, Control)
• Critical considerations
• End of Transfer handling Short Packets and ZLPs
• Handling asynchronous nature of the USB
• Dribble bytes (on 16 and 32 bit CPUs)

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Transfer Firmware IN Transfer

• Usb_Interrupt() For arbitrary length IN transfer
• Read IntStat Which endpoint interrupted?
• Write EpStat Re-arm endpoint interrupt
• Read EpStat Check for Short Packet
• (Short packet? Finish and return)
• Read EpCount Get available FIFO space
• Copy for loop
• Return from Interrupt
• Deep FIFOs

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Transfer Firmware OUT Transfer

• Usb_Interrupt() For arbitrary length OUT
  transfer
• Read IntStat Which endpoint interrupted?
• Write EpStat Re-arm endpoint interrupt
• Read EpCount Get FIFO count (in bytes)
• Read EpStat Check for Short Packet
• (Short Packet? Re-read EpCount)
• Copy for loop (32-bit)
• Return from Interrupt
• Short Packet (ZLP) detection
• NAK OUTs after Short Packet

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Transfer Firmware Summary

• Write critical transfer code to find weak spots
• ZLPs
• Dribble bytes
• Race conditions
• See for yourself Get a development kit

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Development Kits

• Development Kit for a USB 2.0 device
• PCI card with NET2290
• Plugged into Windows PC

USB 2.0 Device
NET2290
USB 2.0 Host
USB Cable
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Development Kits Highlights

• Goals of the kit
• Show the chip in action
• Provide a good HW platform for learning firmware
• Provide Ready to port sample source code
• Allows development without hardware
• Develop your firmware without hardware
• Develop host drivers and apps without hardware
• Prove concepts without hardware
• Includes host-side and device-side tools

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Development Kits Device-Side Software Tools

• USB device-side monitor application
• Interactive and intuitive
• Comprehensive command set
• Full control of
• Chip register content
• Transfer content (fill, copy, compare, )
• Transfer size
• EP0 Standard, Vendor Specific Read and Write
• Multiple commands
• Can you repeat that?

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Development Kits Host-Side Software Tools

• USB Host-Side Monitor Application
• Interactive and intuitive
• Comprehensive command set
• Full control over transfers
• Transfer content (fill, copy, compare, )
• Transfer size
• EP0 Standard, Vendor Specific Read and Write
• Multiple commands
• Can you repeat that?
• Loopback tests

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Your New USB 2.0 Device Rev 1 Prototype Board

• Relaxed board dimensions
• Header pins
• Diagnostic serial port
• Room for emulator pod (if applicable)
• Board layout and USB signal quality

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Your New USB 2.0 Device Development Environment

• A good development environment is priceless
• Tools
• USB bus analyzer
• USB host-side program
• printf()
• History()
• Minimal run-time penalty
• Simple It stores a text key and few parameters
• Example History(TxPk, ExpectLen, GotLen, pBuf)
• Call History() anywhere in your code
• Make a HISTORY() macro (add or remove at compile
  time)
• Examine History memory after problem occurs

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Your New USB 2.0 Device History() Module

• typedef struct _HISTORY_BUF char Text Arg1
  Arg2 Arg3 HISTORY_BUF
• define HISTORY_ENTRIES 1000 // Number of
  historical events
• static HISTORY_BUF HistoBufHISTORY_ENTRIES //
  History is recorded here
• static HistoryCount 0 // Current
  historical event
• void History(char Text, Arg1, Arg2, Arg3)
• memcpy(HistoBufHistoryCount.Text, Text,
  4) // Text key (E.g. TxCo
• HistoBufHistoryCount.Arg1 Arg1
• HistoBufHistoryCount.Arg2 Arg2
• HistoBufHistoryCount.Arg3 Arg3
• HistoryCount // Prepare for next event
• if (HistoryCount gt HISTORY_ENTRIES)
• HistoryCount 0 // History rewrites itself
• memset(HistoBufHistoryCount, 0,
  sizeof(HISTORY_BUF)) // Easy to spot
  terminator

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Your New USB 2.0 Device Bringing up the Board

• Take small steps!
• Prove register access
• Prove interrupt subsystem
• Vendor Specific enumeration
• Basic IN and OUT transfers
• Loopback transfers
• Special transfers
• Special enumeration

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Your New USB 2.0 Device Enumeration

• Everything has to work at the same time
• You cant single step (except PDK)
• Things that can cause enumeration failures
• Set Address request (gotcha!)
• Signal quality
• Descriptor content
• and plenty more!
• Use Vendor Specific enumeration first

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Your New USB 2.0 Device - Bringing up the
Board

• Take small steps!
• Prove register access
• Prove interrupt subsystem
• Vendor Specific enumeration
• Basic IN and OUT transfers
• Loopback transfers
• Special transfers (Control, ISO, Interrupt)
• Special enumeration (for class devices)
• Debugger Gotcha

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NET2290 A Few Special Features

• Built-in Standard Request handlers
• Automatic Enumeration
• Class devices must handle Get Configuration
• Self configuring FIFOs
• Ready signal on FIFO access
• and more!

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Question and Answers
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www.netchip.com
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Thank You! From Ryan Augustin and

• NetChip Technology, Inc.
• www.netchip.com