BrightSign HD600 Hardware Guide - Manual (Page 13)

BrightSign HD600
This information applies to a product under development. Its characteristics and specifications are subject to change without notice. Roku assumes no
obligation regarding future manufacturing unless otherwise agreed to in writing.
www.rokulabs.com © Roku 2006
Video Encoder and Filter
The PNX1500 streams decoded video out of the VDO port using a double data rate clock. In other words,
12 bits of video data is clocked out of the PNX1500 on the rising edge of the VDO_CLK signal, and on
the dalling edge as well. This allows the PNX1500 to output 24 bits of data at a 74.25MHz rate, using
only a single 74.25MHz clock and 12 data lines. The SAA7105 video encoder takes the VDO data in and
sends the data straight to the video DACs in HD mode. In Composite or S-Video mode then the encoder
creates the proper signals in internal blocks for each type of video. The SAA7105 also has an internal
SYNC engine that is only used in HD mode to add video sync to the GREEN component signal. In VGA
mode, the sync signals from the PNX1500 and are passed through the SAA7105. The SAA7105 mode is
controlled by IIC from the PNX1500. Analog video comes out of the SAA7105 and is connected to the
Fairchild FMS6346MTC20 video filter chip. This chip has a programmable cutoff frequency of either
8MHz or 32MHz. When the HD600 is outputting Composite or S-Video, the filter chip is in 8MHz cutoff
mode. When outputting all other modes, then the filter is in 32MHz cutoff mode. Since the video filter
has a low impedance output, we can drive both VGA and COMPONENT 75Ohm terminated cables at the
same time with no degradation (with the same signal).
Audio outputs
The HD600 has three audio DAC devices, which are Philips UDA1334. These devices take in digital
audio signals from the PNX1500 for AO_SCK, AO_WS, and AO_SDX. The AO_WS signal is the
framing signal for the audio, running at the frame rate of the audio source. The frame rate is usually either
44.1KHz or 48KHz. AO_SCK signal is typically 64 times higher than AO_WS, The PNX1500 The
UDA1334 device has a built in PLL so it can generate the internal 4X oversampling clock from the
A)_SCK. The output of the UDA1334 device is left and right analog audio.
SPDIF output
The PNX1500 can generate the SPDIF audio signal internally. This signal, called SPDIF_OPT is
connected to a OPTICAL SPDIF transmitter chip on the board.
On Board LEDs
There are 18 on board LEDs. One of the LEDs is red in color and is designated to be the BUSY LED. Six
of the LEDs are the resolution LEDs, intended to tell the user what resolution the HD600 is currently
outputting. The other LEDs are intended to tell the user which output connectors are active. All the LEDs
are controlled by a set of 3 74HC574 latches. Data is latched into the latches under GPIO control.
On Board Switch
The on board switch is connected to a GPIO55. There is a pullup on the button so that GPIO55 is high
normally, and it is pulled low when the button is pressed.
IR Receiver
The IR receiver receives a 38KHz IR signal. The IR signal is filtered and demodulated and then sent into
the PNX1500 on GPIO60. The signal is called IR_DAT on the schematic.