Introduction to USB/LPC23xx

Transcription

1 Introduction to USB/LPC23xx Amitkumar (Amit) Bhojraj Business Line Standard IC s Product Line Microcontrollers October 2007

2 Introduction to USB Agenda LPC23xx Block diagram MCB2300 demo 2

3 Introduction to USB- Contents Device endpoint Transfer types Bus Enumeration and Descriptors 3

4 Endpoint 4

5 Endpoint Explained (1) An endpoint is a buffer used to transmit or receive data Each endpoint has a direction and an address All USB transfers are targeted to/from a device endpoint Up to 32 (16 pairs) endpoints can reside within a device Although a host has buffers, it does not have endpoints 5

6 Endpoint Explained (2) Types of Endpoint OUT transactions are to the device IN transactions are from the device The direction is from the host s perspective HOST Control Endpoint A Control endpoint actually contains both an IN and OUT endpoint Endpoint 0 is always the Control endpoint OUT IN 6

7 Transfer Types 7

8 Transfer Types = USB Applications Control- Used in every USB application Interrupt- Mouse, Keyboard Isochronous- Audio, Video Bulk- Printers, scanners 8

9 Control Transfer (1) Non-periodic Enables the host to read information about the device (enumeration) All devices must support Control Transfers over the default pipe at Endpoint 0 Control transfers require both an IN and OUT Endpoint Talks to the device through Address 0 while enumeration Maximum Packet Size: 8,16,32,64 9

10 Control Transfer (2) SETUP STAGE DATA STAGE STATUS STAGE 10

11 Interrupt Transfer (1) Periodic Device never interrupts the host. Host polls the device Only way low speed devices can transfer data Also used by the host to send data to the device on a scheduled basis Maximum packet size: 1-64 Typical Devices- Mouse, Keyboard 11

12 Interrupt Transfer (2) DATA STAGE 12

13 Bulk Transfer (1) Non-periodic.Used for large amount of data Only full and high-speed devices Host controller ensures that bulk transfer are eventually completed but it does not guarantee bandwidth Fastest transfer type on an otherwise idle bus Maximum packet size: 8,16,32,64,512 Typical Devices- Printers, USB memory sticks 13

14 Bulk Transfer (2) DATA STAGE 14

15 Isochronous Transfer (1) Fixed number of bytes per frame. Bandwidth is guaranteed No error correction No ACK field Used for continuous communication of time-relevant information (streaming data) Full and high-speed devices only Maximum Packet size: Typical devices- Speakers, microphone, camera, video 15

16 Isochronous Transfer (2) DATA STAGE 16

17 USB Communication Blocks (1) Transfer Transfer Types Control Interrupt Bulk Isochronous Transaction Transaction Transaction Types OUT IN SOF (Start of Frame) SETUP Token Packet Data Packet Handshake Packet 17

18 USB Communication Blocks (2) 18

19 Bus Enumeration & Descriptors 19

20 What is enumeration? The process of identifying and configuring USB devices Host software responsibility During enumeration, devices move through four device states: Powered Default (address 0) Addressed Configured 20

21 Descriptors Data Structure with a defined format that enables a host to learn about a device and its capabilities. Device Descriptor Configuration Descriptor Interface Descriptor Interface Descriptor Endpoint Descriptor Endpoint Descriptor Endpoint Descriptor Endpoint Descriptor 21

22 USB Descriptors (example) DeviceDescriptor: DB 18, 1, ; Length, Type DB 10H, 1, ; USB Rev 1.1 (=0110H, low=10h, High=01H) DB 0, 0, 0, ; Class, Subclass and Protocol DB 16, ; EP0 size DW CC04H, 3209H, 0100H, ; Vendor ID (Philips = 04CC), Product ID (0932) ; and Version (0001) DB 1, 2, 3, ; Manufacturer, Product & Serial# Names ;(pointers to Strings IDs) DB 1, ; #Configs ConfigurationDescriptor: DB 9, 2, ; Length, Type DB LOW(ConfigLength), HIGH(ConfigLength), DB 1, 1, 0, ; #Interfaces, Configuration#, Config. Name DB b, ; Attributes = Self powered DB 0, ; self-powered, therefore uses no bus power EndpointDescriptor1_in: DB 7, 5, ; Length, Type DB b, ; Address = IN 2 DB b, ; Interrupt DB 10H, 0, ; Maximum packet size = 16 bytes DB 100, ; Poll every 100 msec (OS will round down to 32) 22

23 LPC

24 LPC2300 Family 24

25 LPC2378 (1) 25

26 LPC2378 (2) 26

27 Dual AHB Concurrent operations become possible: Ethernet packet reception and transfer to SRAM CPU Instruction Fetch USB packet reception and transfer to SRAM GP DMA Dedicating AHB Bus to Ethernet is required to guarantee 100 Mbits/sec Ethernet throughput without contention with other peripherals 27

28 Serial Communication Interfaces UART0 / 1 I 2 C Interface SPI Interface SSP Interface CAN USB I 2 S Interface Ethernet

29 USB 2.0 Fully Compliant with USB 2.0 Spec Supports 32 physical endpoints. Supports Control, Bulk, Interrupt and Isochronous endpoints Scalable realization of Endpoints at Run time Double buffering supported for Bulk and Isochronous Endpoints Supports DMA transfer on all non-control endpoints 29

30 Available USB Device Stacks for LPC2300/2400/214x (list does not claim to be complete ) Keil RL-USB: Micrium µc/usb Device Micro Digital smxusbd HCC Embedded USB (EUSB) Device Stack CMX-USB Express Logic USBX 30

31 Available USB Host Stacks for LPC2400/ LPC3180 (list does not claim to be complete ) Micrium µc/usb Host Micro Digital smxusbh HCC Embedded USB (EUSB) HostLite Stack Express Logic USBX OnChip Technology 31

32 MCB2300 Demo 32

33 33