PS20230 Datasheet, PDF (19/26 Pages) List of Unclassifed Manufacturers – COFDM demodulator with USB interface for PC-TV

PS20230
8 USB implementation
The PS20230 provides 3 USB endpoints:
• Endpoint 0 is the default control endpoint. This is used for all control operations of the PS20230. The
format of the data is completely user-defined (except for standard USB commands).
• Endpoint 1 is an Interrupt IN endpoint. This can be used by the 8051 to report events (such as infra-
red key-presses) to the host PC. The format of the data is completely user-defined.
• Endpoint 2 is either an Isochronous IN endpoint or a Bulk IN endpoint.. This is used to transfer MPEG
transport stream data to the PC. This is a hardware interface – once set up, the transfers will occur
independently of the 8051.
In isochronous transfer mode the PS20230 has the ability to insert a header before each MPEG transport
stream transfer. The length of the header can be from 1 to 4 bytes but will usually be set to 2 for compliance
with the Device Class Definition for Video Devices with MPEG2-TS Payload.
The PS20230 can support up to 3 USB configurations (1 to 3), each of which can have up to 3
interfaces (0 to 2). There can be up to 15 alternate settings (0 to 14) for each interface.
All control operations use endpoint 0.
8.1 Suspend mode
USB devices must support a suspend mode in which the current drawn from the bus must be less than
500 µA. For remote-wakeup enabled devices this limit is raised to 2.5 mA, but only when the remote-
wakeup feature has been enabled by the PC. The PC requests device suspend mode by stopping USB
activity for more than 3 ms.
8.2 Infra-Red detector
The infra-red detector should be connected to pin IRDI. A rising edge on IRDI will set interrupt INT2, a
falling edge will set INT0_N. These interrupts, together with the 8051 timers, can be used to measure the
pulse widths on the infra-red symbols. The 8051 can decode the pulse sequence into a keypad code which
can be sent over interrupt endpoint 1 to the PC.
If the device is configured as remote-wakeup capable remote-wakeup using pin IRDI should work
automatically without requiring software intervention.
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