HD6417727BP160CV Datasheet, PDF (819/1098 Pages) Renesas Technology Corp – Renesas 32-Bit RISC Microcomputer SuperH™ RISC engine Family/ SH7700 Series

Section 24 USB HOST Module
Note: The prohibition on consecutive 0 bits applies to all bits of SYNC + PID + DATA +
CRC16 + EOP. EOP is counted as 2 bits.
Explanation of Terms
• SE0: USB data transfer uses a D+/D– differential signal. Consequently, D+/D– is normally a
reciprocal signal. However, in some special cases D+ and D– are both defined as low. This
state is referred to as SE0.
• Device not connected detection: Detection of a USB device not connected state when SE0
continues beyond the device not connected detection duration.
24.8 Usage Notes of Resume Operation of USB Host Controller (USBH)
1. Phenomenon
While the USB host is providing an output of a Resume *¹ signal, suppose that (a) PortPower
is turned off or that (b) OverCurrent is produced. In this case, the Resume signal should
ordinarily be stopped so that the idle *² state will be established. Actually, however, the result
is that an idle signal is output.
Notes: 1. In FullSpeed, D+ = Low and D- = High. In LowSpeed, D+ = High and D- = Low.
2. In FullSpeed, D+ = High and D- = Low. In LowSpeed, D+ = Low and D- = High.
2. Conditions when the above phenomenon occurs
While a Resume *¹ signal is being output, (a) PortPower is turned off or (b) OverCurrent is
produced.
3. Conditions when the above phenomenon does not occur
The above phenomenon will not occur if there is no Resume operation, that is, Suspend
operation has not been done.
4. Workaround by software
If the above phenomenon occurs, Resume is interrupted and then an idle signal is output.
However, turning on PortPower enables device recognition. The above phenomenon is
removed by the subsequent Port Reset for the device. Normal operation is thus recovered.
Note, however, the above phenomenon will not be removed by USB Reset, which is generated
by the HCFS1 and HCFS0 bits in the HcControl (USBHC) register. For this reason, if you are
using software that issues USB Reset by the HCFS1 and HCFS0 bits in the HcControl
(USBHC) register, modify the software so that it issues Port Reset by setting the PRS bit in the
HcRhPortStatus1 or HcRhPortStatus2 (USBHRPS1 or USBHRPS2) register. However, there
is no need to take corrective action if Port Reset has already been issued by the PRS bit before
the recognition of USB device connection.
Rev.6.00 Mar. 27, 2009 Page 761 of 1036
REJ09B0254-0600