MC9328MX21_10 Datasheet, PDF (61/100 Pages) Freescale Semiconductor, Inc – 266 MHz i.MX family of microprocessors

Specifications
3.18 USB On-The-Go
Four types of data transfer modes exist for the USB module: control transfers, bulk transfers, isochronous
transfers and interrupt transfers. From the perspective of the USB module, the interrupt transfer type is
identical to the bulk data transfer mode, and no additional hardware is supplied to support it. This section
covers the transfer modes and how they work from the ground up.
Data moves across the USB in packets. Groups of packets are combined to form data transfers. The same
packet transfer mechanism applies to bulk, interrupt, and control transfers. Isochronous data is also moved
in the form of packets, but because isochronous pipes are given a fixed portion of the USB bandwidth at
all times, there is no end-of-transfer.
USB_ON
(Output)
USB_OE
(Output)
1 ^t OEB_TXDP
USB_TXDP
(Output)
t_PERIOD ⁶
t _{TXDM_OEB} 4
3
t_{TXDP_OEB}
USB_TXDM
(Output)
USB_VP
(Input)
t_{OEB_TXDM}
2
t_{FEOPT 5}
USB_VM
(Input)
Figure 50. USB Timing Diagram for Data Transfer to USB Transceiver (TX)
Table 40. USB Timing Parameters for Data Transfer to USB Transceiver (TX)
Ref
No.
Parameter
1 t_{OEB_TXDP}; USBD_OE active to USBD_TXDP low
2 t_{OEB_TXDM}; USBD_OE active to USBD_TXDM high
3 t_{TXDP_OEB}; USBD_TXDP high to USBD_OE deactivated
4 t_{TXDM_OEB}; USBD_TXDM low to USBD_OE deactivated (includes SE0)
5 t_FEOPT; SE0 interval of EOP
6 t_PERIOD; Data transfer rate
3.0 V ± 0.3 V
Minimum
83.14
81.55
83.54
248.9
160
11.97
Maximum
83.47
81.98
83.8
249.13
175
12.03
Unit
ns
ns
ns
ns
ns
Mb/s
MC9328MX21 Technical Data, Rev. 3.4
Freescale Semiconductor
61