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Revision 2.2 (02-17-12)
2
SMSC USB251xB/xBi
DATASHEET
USB 2.0 Hi-Speed Hub Controller
Datasheet
Conventions
Within this manual, the following abbreviations and symbols are used to improve readability.
Example
BIT
FIELD.BIT
Description
Name of a single bit within a field
Name of a single bit (BIT) in FIELD
Range from x to y, inclusive
Groups of bits from m to n, inclusive
Pin Name
Binary number (value zzzz)
Hexadecimal number (value zzz)
Hexadecimal number (value zz)
Reserved memory location. Must write 0, read value indeterminate
Instruction code, or API function or parameter
Section or Document name
Don’t care
<> indicate a Parameter is optional or is only used under some conditions
Braces indicate Parameter(s) that repeat one or more times
Brackets indicate a nested Parameter. This Parameter is not real and actually decodes
The debug script reads out that a register is 1 after power-on. This section of code is generated by a for loop. The initial values of the other registers are normal and there is no problem with the t...
Embedded systems inevitably have to deal with chip registers, and register operations require bit operations.
I won’t talk about the basic operations such as clearing a bit and setting a bit, but let’...
I have used protel 99 and AD 17, and I have been drawing low-speed PCBs. Although I have been in the industry for many years, I have not studied PCB knowledge in depth. Recently, I want to learn orcad...
Let us briefly discuss what is LDO.Low Dropout RegulatorA low dropout or LDO regulator is a DC linear regulator that can control the output voltage even when the input voltage provided to it is almost...
Why does I2C need a pull-up resistor? Because it is an open-drain output.Why open drain output?
The I2C protocol supports multiple master devices and multiple slave devices on one bus. If push-pull ou...
An important wireless technology will make its debut, Ultra-Wideband (UWB) technology. Let's take a closer look.When you think of wireless technology, the first ones that come to mind are those that h...
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