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October 11, 2000. 2. Firmware for USB 2.0. Ryan Augustin Netchip Technology, Incryan@netchip.com. October 11, 2000. 3. . Agenda. USB 2.0 device-side programmingNew USB 2.0 features: a programmer's glossaryChoosing a chip from a programmer's perspectivePerformance: fast transfers, race conditionsDevelopment aids:Standard tools (USB analyzer)Manufacturer's Tools and supportYour
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1. October 11, 2000 1
2. October 11, 2000 2 Firmware for USB 2.0 Ryan AugustinNetchip Technology, Inc
ryan@netchip.com
3. October 11, 2000 3 Agenda USB 2.0 device-side programming
New USB 2.0 features: a programmer’s glossary
Choosing a chip from a programmer’s perspective
Performance: fast transfers, race conditions
Development aids:
Standard tools (USB analyzer)
Manufacturer’s Tools and support
Your “Rev 1” board: Tips, hints, steps to success
4. October 11, 2000 4 USB 2.0 Glossary, Features – For the Chip Programmer Glossary
CHIRP - Device/host: Who’s 2.0, who’s 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)
5. October 11, 2000 5 USB 2.0 Max Packet Size
6. October 11, 2000 6 Choosing a Chip –Programmers Perspective Get involved choosing the chip
Understand the hardware designer’s 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
7. October 11, 2000 7 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
8. October 11, 2000 8 Transfer Firmware –Programmed I/O IN and OUT transfer firmware:
Interrupt handlers
Arbitrary length transfers (zero to a zillion+1)
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)
9. October 11, 2000 9 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
10. October 11, 2000 10 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
11. October 11, 2000 11 Transfer Firmware –Summary Write critical transfer code to find weak spots
ZLPs
Dribble bytes
Race conditions
See for yourself: Get a development kit
12. October 11, 2000 12 Development Kits
13. October 11, 2000 13 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
14. October 11, 2000 14 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?
15. October 11, 2000 15 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
16. October 11, 2000 16 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
17. October 11, 2000 17 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
18. October 11, 2000 18 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 HistoBuf[HISTORY_ENTRIES]; // History is recorded here
static HistoryCount = 0; // Current historical event
void History(char * Text, Arg1, Arg2, Arg3) {
memcpy(&HistoBuf[HistoryCount].Text, Text, 4); // Text key (E.g. “TxCo”
HistoBuf[HistoryCount].Arg1 = Arg1;
HistoBuf[HistoryCount].Arg2 = Arg2;
HistoBuf[HistoryCount].Arg3 = Arg3;
HistoryCount++; // Prepare for next event
if (HistoryCount >= HISTORY_ENTRIES) {
HistoryCount = 0; // History rewrites itself
}
memset(&HistoBuf[HistoryCount], 0, sizeof(HISTORY_BUF)); // “Easy to spot” terminator
}
19. October 11, 2000 19 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
20. October 11, 2000 20 Your New USB 2.0 Device –Enumeration Everything has to work at the same time
You can’t 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
21. October 11, 2000 21 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”
22. October 11, 2000 22 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!
23. October 11, 2000 23 Question and Answers
24. October 11, 2000 24 Thank You! From Ryan Augustin and… NetChip Technology, Inc.
www.netchip.com