USB Flashcards
What is Host Controller Interface
Hardware/software interface between system software and host controller hardware
what is the max device that can be connected to the USB port
127
What are the advantages of a USB
Low cost Hot pluggable Single Host controller Cable power No System Requirements Error Detection and Recovery Power Conversation Four types of transfers
What are the four (4) pin connector types
- Vcc (Voltage connector)
- Data
- Data
- Ground
What is a Series A Connector
Provides the USB connection to the USB cable
What is a Series B Connector
Provides the cable connection to the USB device when using a detachable cable
What are the four (4) pin colour code for a USB
RED 1. Vcc (Voltage connector)
BLUE 2. - Data
GREEN 3. + Data
BLACK 4. Ground
True or False
Cable must be both shielded and twisted pair
True
What is the Max length of a USB cable
5m
What is the Max propagation delay
Less than 30ns in the range of 1 to 16 MHz
What is the Max speed of a USB 1
Up to 1.5 MB/s (low Speed)
What is the Max speed of a USB 1.1
Up to 12 MB/s (low Speed)
What is the Max speed of a USB 2
Up to 480 MB/s (High Speed)
What is the Max speed of a USB 3
Up to 4.8 GB/s (Super Speed)
True or False
Can Device be powered directly from the connected cable
True
what is the Max VDC Voltage
5.0 v
What is the current (flow of electrons) range of a USB
100ma to 500ma current
After how long does a USB enter into a suspend state when there is no bus activity
3 ms
How much power does a USB consume after a suspended state
50 ua
What are the four (4) Monitoring USB Activities
- USB Host Controller
- USB2 Enhanced host controller
- USB root Hub
- USB Devices
What are two data transfers
- the Function view
2. The System view
In the function view, what are the four (4) transfers
- Bulk
- Isochronous
- Interrupt
- Control
What does a BULK Transfer do?
Transfers large bulk of data with no restriction
What does a ISOCHRONOUS do?
Used by applications that require a content data rate
What does a INTERRUPT do?
USB that does not support hardware interrupts
What does a CONTROL do?
Used to transfer specific requests to USB devices. Normally used during devices configuration
What is Error Detection and Recovery
Error detection ensures data is delivered without error.
What are the two (2) USB Systems?
Software
Hardware
What are the three (3) systems of of USB Software
- USB Device Drivers
- USB Drivers
- Host Controllers Driver
What are the three (3) systems of of USB Hardware
- USB Host Controllers/Root Hub
- USB Hubs
- USB Devices
What does the USB Device Drivers do?
Provides interfaces and services for clients software drivers
What are the two hardware parts of the host?
USB Host Controller
Root Hub
What is the host controller?
Generate Transactions that have been scheduled by host software
What does a host controller do?
- reads data from the host memory buffer
- performs a parallel to serial conversion of the data
- Data is forwarded to the root hub to be sent over the bus
What is the order of process of the Host controller?
CPU —-> RAM —> UART (Universal Asynchronous Receive Transmit)
What are the four (4) connection points for USB devices
- Control power to USB ports
- Enables and disables ports
- Recognises devices attached to ports
- Sets reports status events associated with each port
What two (2) parts are from the Root hub?
- Hub Controller
2. Hub Repeater
