2/24/2008 9T6WP
Preliminary Hardware Data Module
BCM7405
06/29/07
Functional Description
Bro a d c o m Co rp o r a ti o n
Document
7405-1HDM00-R
Peripherals Page 1-75
Figure 1-21: Digital Front End of UHF Receiver
The data decoder extracts the data packet from the binary FSK datastream generated from DFE. Data decoding is
performed by the Consumer IR (CIR) decoder in the IR Receiver Controller. The CIR decoder can be programmed to decode
some forms of pulse position modulation, pulse width modulation, or bi-phase encoded data. The CIR decoder works by,
first, detecting a user-specified preamble waveform, and, if a match is found, followed by decoding of the data symbol
sequence. User can specify the preamble by programming the Consumer IR Decoder Configuration registers, which are
indirectly accessed through the CIR decoder Address and Data registers. When a valid data packet is received by the
enabled decoder, an interrupt is asserted to the processor if enabled in KBD_CMD[kbd_irqen]. If the interrupt is not enabled,
the interrupting condition may be polled in KBD_STATUS[irq]. The received data packet can be found in KBD_DATA0-4
registers. Details of the register definitions can be found in the KBD_ section of the IR Receiver Controller documentation.
UART
The triple UART provides independent serial interfaces that may be used to control peripherals such as a telephone modem
or an analog descrambler.
General Description
Each UART provides a full-duplex serial interface that can be used to communicate with a device that has a serial interface
(modem, computer, and so on). The UART functions as a serial-to-parallel and parallel-to-serial converter. The UART
handles standard asynchronous NRZ encoded format with seven or eight bits/characters, one stop bit/character, and even,
odd, or no parity. Each UART channel has its own baud rate generator, interrupt logic, 32-character transmit data FIFO, and
32-character receive data FIFO.
shows a UART functional diagram.
N
Filter
Frequency
Discriminator
Adaptive
Slicer
Anti-Aliasing
Filter
N
Filter
10 .7MHz
Digitally Sampled
IF Signal(from AFE)
Carrier offset
To Data
Decoder
Anti-Aliasing
Filter