CY7C66013C_11 Datasheet, PDF (37/61 Pages) Cypress Semiconductor – Full Speed USB (12 Mbps) Peripheral Controller with Integrated Hub

CY7C66013C, CY7C66113C
Hub Ports Resume
Bit #
7
Bit Name Reserved
Read/Write -
Reset
0
Table 43. Hub Ports Resume Status Register
6
Reserved
-
0
5
Reserved
-
0
4
Reserved
-
0
3
Resume 4
R
0
2
Resume 3
R
0
ADDRESS 0x4E
1
0
Resume 2 Resume 1
R
R
0
0
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 [7..4]: Reserved.
The Reserved bits [7..4] should always read as ‘0’.
Resume from a selectively suspended port, with the hub not in
suspend, typically involves these actions:
1. Hardware detects the Resume, drives a K to the port, and
generates the hub interrupt. The corresponding bit in the
Resume 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.
Note Firmware must disable interrupts during this SE0 so the
SE0 pulse is not inadvertently lengthened and appears 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. When 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 is detected on the port. The port is
treated as being reset, and is reported to the host as newly
connected.
Firmware chooses to clear the Device Remote Wakeup bit (if set)
to implement firmware timed states for port changes. All allowed
port changes wake the part. Then, the part uses internal timing
to determine whether to take action or return to suspend. If
Device Remote Wakeup is set, automatic hardware assertions
take place on Resume events.
Document Number: 38-08024 Rev. *G
Page 37 of 61
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