GL800USB データシートの表示（PDF） - Genesys Logic
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GL800USB Datasheet PDF : 23 Pages
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GL800USB - USB2.0 UTMI COMPLIANT TRANSCEIVER
4.2.8 Bit Unstuffer
The Bit Unstuffer is compliant to standard USB 1.X specification, and it can
operate at FS and HS data rates. The bit unstuffer is a state machine, which strips
a stuffed 0 bit from the data stream and detects bit stuff errors. In FS mode bit stuff
errors asserts the RXERR signal. In HS mode bit stuff errors are used to generate
the EOP signal so the RXERR signal is not asserted.
4.2.9 Rx Register
Rx Register is in charge of converting serial data received from the USB to parallel
data.
4.2.10 Receive State Machine
The behavior of the Receive State Machine is described at Chapter 6, Function
Description.
4.2.11 NRZI Encoder
The NRZI Encoder is compliant to standard USB 1.X specification, and it can
operate at FS and HS data rates.
4.2.12 Bit Stuffer
Bit Stuffer is used by insert a zero after every six consecutive ones in the data
stream before the data is NRZI encoded in order to ensure adequate signal
transitions. Bit stuffing is enabled beginning with the SYNC Pattern and through
the entire transmission. The data “one” that ends the SYNC Pattern is counted as
the first one in a sequence.
In FS mode bit stuffing by the transmitter is always enforced, without exception. If
required by the bit stuffing rules, a zero bit is inserted even after the last bit before
the TXVLD signal is negated.
After 8 bits are stuffed into the USB data stream TXRDY is negated for one byte
time to hold up the data stream on the Data bus.
4.2.13 Tx Register
Tx Register is in charge of reading parallel data from the parallel application bus
interface upon command and serializing for transmission over USB.
4.2.14 Transmit State Machine
The behavior of the Transmit State Machine is described at Chapter 6, Function
Description.
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