Altera Serial Digital Interface (SDI) MegaCore Function - Manual (Page 59)

Chapter 3: Functional Description 3–29
Block Description
February 2013 Altera Corporation Serial Digital Interface (SDI) MegaCore Function
User Guide
Transceiver Reconfiguration for Transmitter Clock Multiplexer
The transmitter reconfiguration requires its own Memory Initialization Files (.mif)
that is stored in the device. The .mif contains information about the default selection
of the TX PLL that is based on the logical_tx_pll_sel and logical_tx_pll_sel_en
pins. These pins are available in the transceiver port when you enable the transmitter
clock multiplexer feature. By toggling the values in these ports and reconfiguring the
transmitter megafunction, you can internally switch the TX PLL to select different
reference clock inputs. For Arria II and Stratix IV devices, these are 19-words by 16-
bits files. The following are the sequence of events that occur during the SDI
transmitter clock toggling:
1. SDI MegaCore function detects a change request to the serial reference clock.
2. The ALTGX_RECONFIG block reads the appropriate ROM, sets the
logical_tx_pll_sel and logical_tx_pll_sel_en ports to the required value, and
reprograms the ALTGX in the transmitter block.
3. When step 2 is completed, the SDI transmitter begins locking on the new serial
reference clock.
1
User logic is required in handling the handshaking between the SDI MegaCore
function and the ALTGX_RECONFIG block.
1 By default, the receiver reconfiguration has higher priority than the transmitter
reconfiguration.
Transceiver Reconfiguration for Receiver
The ROMs store the alternative setups for the transceiver settings within the device.
These setups are 28 words by 16 bits for Arria GX and Stratix II GX devices, and
38 words by 16 bits for Arria II and Stratix IV devices. The ALT2GXB megafunction
has a serial reprogramming interface, so the ALT2GXB_RECONFIG block must
serialize this parallel data before loading.
The following sequence of events occur during an SDI receiver rate change:
1. SDI MegaCore function detects the incoming video rate and requests
reprogramming.
2. The ALT2GXB_RECONFIG block reads the appropriate ROM, serializes the data,
and applies the serial data to the correct transceiver instance.
3. When step 2 is completed, the ALT2GXB_RECONFIG block indicates to the SDI
that reprogramming is complete.
4. The SDI starts the process of locking to the incoming data.
1
Some user logic is required to handle the handshaking between the SDI
MegaCore function and the ALT2GXB_RECONFIG megafunction. For
example, refer to the example design in the
example\s2gx_tr\source\sdi_dprio
directory.