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2. USB
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9. USB -
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USB (Universal Serial Bus ) PC, . 1.0 1996 . USB :
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(Upstream Port), . (Downstream Ports), .
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USB . USB , . - , . , . 7.1.
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* USB System SW - USB, .
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3.
USB . 5 . D+ D- . 0,3 ( ) 2,8 ( ). - 0,5...+3,8 . .
USB . D+ D-, . , . Diff0 Diff1 D+ D- 200 , VSE. , D+ D- , (SEO - Single-Ended Zero). :
* Data J State Data State - ( J ), Diff0 Diff1.
* Idle State - .
* Resume State - "" "" .
* Start of Packet (SOP) - ( Idle State ).
* End of Packet (EOP) - .* Disconnect - .* Connect - .* Reset - .
; DiffO Diff1 . Disconnect, Connect Reset ( 2,5 ) .
. USB 12 /, - 1,5 /. 90 5 , - 3 . . ; . , . , , , D+ D-, R2 (. . 7.2 7.3).
NRZI (Non Return to Zero Invert), . 7.4. SYNC, . VBus GND 5 . .
(. . 7.1 . 7.5).
1 | VBus | 3 | D+ |
2 | D- | 4 | GND |
"" (Upstream Connector). , (, , . .). (Downstream Port) . "" (Downstream Connector) , ( ). () , "".
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"" "" (. 7.5), . , . . USB .
USB (Bus-Powered Devices) (Self-Powered Devices). . , , , . , . . 7.6 USB. , .
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USB , . . , () .
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* (Bulk Data Transfers) . . 8, 16, 32 64 . , . .
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, . . Sync, KJKJKJKK (- NRZI), Idle. () SOP, PID. 4- PID[3:0], (. 7.2), 4 , .
PID | PID | PID[3:0] | |
Token | OUT | 0001 | - |
Token | IN | 1001 | - |
Token | SOF | 0101 | |
Token | SETUP | 1101 | - |
Data | DataODatal | 00111011 | PID |
Handshake | Ack | 0010 | |
Handshake | NAK | 1010 | . (). |
Handshake | STALL | 1110 | |
Special | PRE | 1100 |
- IN, SETUP OUT : 7- 4- . 127 USB ( ) 16 .
SOF 11- (Frame Number Field), () .
0 1023 . .
- , , PID. CRC (5 ) (11 ) .
- . . 7.7.
- . ( 1 ) (Frames), . SOF (Start Of Frame), , . EOF (End Of Frame), . . - 32- , SOF 11 . () EOF. , . (Bulk Transfers).
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