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Figure 6-9 Block Diagram of the HDMI TX Demonstration
A NIOS-II softcore is used to execute user program and send control-commands to the HDMI
encoder via the I2C interface. The interrupt events from the HDMI encoder are sent back to the
NIOS-II softcore via the HDMI_TX_INT signal. In this demonstration the hot-plug and
monitor-sense interrupts are enabled in the HDMI encoder (ADV7513). When any of the these
interrupt is asserted, the corresponding ISR, which is registered by the control program, in the
NIOS-II system will check current HPD and monitor-sense state reported in one of the encoder
registers. If both HPD and monitor-sense are confirmed to be asserted, the ISR will try to power up
the encoder chip and program it to interpret the incoming video signals. The HDMI encoder then
will detect the video timing automatically and send out video data via the HDMI cable. The
monitor-sense interrupt will continue to be asserted whenever the HDMI cable is connected. So it is
disabled in the ISR until the cable is un-plugged. As soon as the HDMI cable is un-plugged, the ISR
will again be asserted by the HPD interrupt. Then the monitor-sense interrupt will be re-enabled,
along with making all other necessary settings, in preparation for the next time hot-plug event.
