User`s guide

CY7C66013
C
CY7C66113
C
Document #: 38-08024 Rev. *B Page 37 of 61
which (if any) of the downstream ports need to be enumerated. The following is a brief summary of the typical enumeration
process of the CY7C66x13C by the USB host. For a detailed description of the enumeration process, refer to the USB specifi-
cation.
In this description, “Firmware” refers to embedded firmware in the CY7C66x13C controller.
1. The host computer sends a SETUP packet followed by a DATA packet to USB address 0 requesting the Device descriptor.
2. Firmware decodes the request and retrieves its Device descriptor from the program memory tables.
3. The host computer performs a control read sequence and Firmware responds by sending the Device descriptor over the USB
bus, via the on-chip FIFOs.
4. After receiving the descriptor, the host sends a SETUP packet followed by a DATA packet to address 0 assigning a new USB
address to the device.
5. Firmware stores the new address in its USB Device Address Register (for example, as Address B) after the no-data control
sequence completes.
6. The host sends a request for the Device descriptor using the new USB address.
7. Firmware decodes the request and retrieves the Device descriptor from program memory tables.
8. The host performs a control read sequence and Firmware responds by sending its Device descriptor over the USB bus.
9. The host generates control reads from the device to request the Configuration and Report descriptors.
10.Once the device receives a Set Configuration request, its functions may now be used.
11.Following enumeration as a hub, Firmware can optionally indicate to the host that a compound device exists (for example, the
keyboard in a keyboard/hub device).
12.The host carries out the enumeration process with this additional function as though it were attached downstream from the hub.
13.When the host assigns an address to this device, it is stored as the other USB address (for example, Address A).
18.0 USB Hub
A USB hub is required to support:
• Connectivity behavior: service connect/disconnect detection
• Bus fault detection and recovery
• Full-/low-speed device support.
These features are mapped onto a hub repeater and a hub controller. The hub controller is supported by the processor integrated
into the CY7C66013C and CY7C66113C microcontrollers. The hardware in the hub repeater detects whether a USB device is
connected to a downstream port and the interface speed of the downstream device. The connection to a downstream port is
through a differential signal pair (D+ and D–). Each downstream port provided by the hub requires external R
UDN
resistors from
each signal line to ground, so that when a downstream port has no device connected, the hub reads a LOW (zero) on both D+
and D–. This condition is used to identify the “no connect” state.
The hub must have a resistor R
UUP
connected between its upstream D+ line and V
REG
to indicate it is a full speed USB device.
The hub generates an EOP at EOF1, in accordance with the USB 1.1 Specification, Section 11.2.2.
18.1 Connecting/Disconnecting a USB Device
A low-speed (1.5 Mbps) USB device has a pull-up resistor on the D– pin. At connect time, the bias resistors set the signal levels
on the D+ and D– lines. When a low-speed device is connected to a hub port, the hub sees a LOW on D+ and a HIGH on D–.
This causes the hub repeater to set a connect bit in the Hub Ports Connect Status register for the downstream port. Then the hub
repeater generates a Hub Interrupt to notify the microcontroller that there has been a change in the Hub downstream status.
A full-speed (12 Mbps) USB device has a pull-up resistor from the D+ pin, so the hub sees a HIGH on D+ and a LOW on D–. In
this case, the hub repeater sets a connect bit in the Hub Ports Connect Status register, clears a bit in the Hub Ports Speed register
(for full-speed), and generates a Hub Interrupt to notify the microcontroller of the change in Hub status. The firmware sets the
speed of this port in the Hub Ports Speed Register (see Figure 18-2)
Connects are recorded by the time a non-SE0 state lasts for more than 2.5 µs on a downstream port.
When a USB device is disconnected from the Hub, the downstream signal pair eventually floats to a single-ended zero state. The
hub repeater recognizes a disconnect once the SE0 state on a downstream port lasts from 2.0 to 2.5 µs. On a disconnect, the
corresponding bit in the Hub Ports Connect Status register is cleared, and the Hub Interrupt is generated.