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| PIC32MX440F256H-80I Datasheet, PDF (295/646 Pages) Microchip Technology – 64/100-Pin General Purpose and USB 32-Bit Flash Microcontrollers | |||
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PIC32MX3XX/4XX
TABLE 11-5: EXAMPLE OF SOF THRESHOLD CALCULATION: LOW SPEED VIA HUB
Packet
Fields
Bits
FS Bits
PRE
SYNC, PID
16
16
Hub setup
IN
Turnaround(1)
DATA
Turnaround
SYNC, PID, ADDR, ENDP, CRC5, EOP
SYNC, PID, DATA(2), CRC16, EOP
4
4
35
280
8
8
99
792
2
2
PRE
SYNC, PID
16
16
HANDSHAKE
Inter-packet
SYNC, PID, EOP
19
152
2
2
Total
1272
Note 1: Inter-packet delay of 2. An additional 5.5 bit times of latency is added to represent a worst-case propaga-
tion delay through 5 hubs.
2: Packets limited to 8-bytes maximum in Low-Speed mode.
Note:
Refer to Section 5.11.3 âCalculating Bus
Transaction Timesâ in the USB 2.0 spec-
ification for details on calculating bus
transaction time.
© 2008 Microchip Technology Inc.
Preliminary
DS61143E-page 293
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