AT43USB326-AU Atmel, AT43USB326-AU Datasheet - Page 67

• Manufacturer Part Number: AT43USB326-AU
• Description: IC USB KEYBOARD CTRLR 48LQFP
• Manufacturer: Atmel
• Series: AVR®r

Specifications of AT43USB326-AU

• Applications: Keyboard Controller
• Core Processor: AVR
• Program Memory Type: Mask ROM (16 kB)
• Controller Series: AT43USB
• Ram Size: 512 x 8
• Interface: USB
• Number Of I /o: 32
• Voltage - Supply: 4.4 V ~ 5.25 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 48-LQFP
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

Selective Suspend
and Resume
3313D–USB–04/06
The host can selectively suspend and resume a port through the Set Port Feature
(PORT_SUSPEND) and Clear Port Feature (PORT_SUSPEND).
A port enters the suspend state after the microcontroller interprets the suspend request and
sets the appropriate bits of the Hub Port Control Register, HPCON. From this point on he hub
repeater hardware is responsible for proper actions in placing Ports 2:3 in the suspend mode.
For Port 1, the embedded function port, the hardware will stop responding to any normal bus
traffic, but the microcontroller firmware must place all external circuitry associated with the
function in the low-power state.
A port exits from the suspend state when the hub receives a Clear Port Feature
(PORT_SUSPEND) or Set Port Feature (PORT_RESET). If the Clear Port Feature
(PORT_SUSPEND) is directed towards Ports 2:3, the USB hardware drives a “K” downstream
for at least 20 ms followed by a low speed EOP. It then places the port in the enabled state. A
Clear Port Feature (PORT_SUSPEND) to Port 1 (the embedded function) causes the firmware
to wait 20 ms, take the embedded function out of the suspended state and then enable the
port.
The ports can also exit from the suspended state through a remote wakeup if this feature is
enabled. For Ports 2:3, this means detection of a connect/disconnect or an upstream directed
J to K signaling. Remote wakeup for the embedded function is initiated through an external
interrupt at INT0.
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