User`s guide

CY7C65113C
Document #: 38-08002 Rev. *G Page 30 of 48
Figure 29. Hub Ports Suspend Register
Bit [0..3]: Port x Selective Suspend (where x = 1..4).
Set to 1 if Port x is Selectively Suspended; Set to 0 if Port
x Do not suspend.
Bit 7: Device Remote Wakeup.
When set to 1, Enable hardware upstream resume signal-
ing for connect/disconnect events during global resume.
When set to 0, Disable hardware upstream resume signal-
ing for connect/disconnect events during global resume.
Figure 30.
Hub Ports Resume Status Register
Bit [0..3] : Resume x (where x = 1..4).
When set to 1 Port x requesting to be resumed (set by
hardware); default state is 0.
Bit [4..7]: Reserved.
Set to 0.
Resume from a selectively suspended port, with the hub not in
suspend, typically involves the following actions:
1. Hardware detects the Resume, drives a K to the port, and
generates the hub interrupt. The corresponding bit in the Re-
sume Status Register (0x4E) reads ‘1’ in this case.
2. Firmware responds to hub interrupt, and reads register 0x4E
to determine the source of the Resume.
3. Firmware begins driving K on the port for 10 ms or more
through register 0x4B.
4. Firmware clears the Selective Suspend bit for the port (0x4D),
which clears the Resume bit (0x4E). This ends the
hardware-driven Resume, but the firmware-driven Resume
continues. To prevent traffic being fed by the hub repeater to
the port during or just after the Resume, firmware should
disable this port.
5. Firmware drives a timed SE0 on the port for two low-speed bit
times as appropriate. Firmware must disable interrupts during
this SE0 so the SE0 pulse isn’t inadvertently lengthened, and
appear as a bus reset to the downstream device.
6. Firmware drives a J on the port for one low-speed bit time,
then it idles the port.
7. Firmware re-enables the port.
Resume when the hub is suspended typically involves these
actions:
1. Hardware detects the Resume, drives a K on the upstream
(which is then reflected to all downstream enabled ports), and
generates the hub interrupt.
2. The part comes out of suspend and the clocks start.
3. Once the clocks are stable, firmware execution resumes. An
internal counter ensures that this takes at least 1 ms.
Firmware should check for Resume from any selectively
suspended ports. If found, the Selective Suspend bit for the
port should be cleared; no other action is necessary.
4. The Resume ends when the host stops sending K from
upstream. Firmware should check for changes to the Enable
and Connect Registers. If a port has become disabled but is
still connected, an SE0 has been detected on the port. The
port should be treated as having been reset, and should be
reported to the host as newly connected.
Firmware can choose to clear the Device Remote Wake-up bit (if
set) to implement firmware timed states for port changes. All
allowed port changes wake the part. Then, the part can use
internal timing to determine whether to take action or return to
suspend. If Device Remote Wake-up is set, automatic hardware
assertions take place on Resume events.
USB Upstream Port Status and Control
USB status and control is regulated by the USB Status and
Control Register, as shown in Figure . All bits in the register are
cleared during reset.
Hub Ports Suspend Address 0x4D
Bit # 76543210
Bit Name Device
Remote
Wakeup
Reserved Reserved Reserved Port 4
Selective
Suspend
Port 3
Selective
Suspend
Port 2
Selective
Suspend
Port 1
Selective
Suspend
Read/Write R/W R/W R/W R/W R/W R/W R/W R/W
Reset 00000000
Hub Ports Resume Address 0x4E
Bit # 76543210
Bit Name Reserved Reserved Reserved Reserved Resume 4 Resume 3 Resume 2 Resume 1
Read/Write - - - - R R R R
Reset 00000000