HC4GX15 Datasheet, PDF (504/668 Pages) Altera Corporation – HardCopy IV Device Handbook

2–46
Chapter 2: HardCopy IV GX Dynamic Reconfiguration
Offset Cancellation Control for Receiver Channels
Figure 2–15 shows the Offset cancellation for Receiver channels option enabled by
default in the ALTGX_RECONFIG MegaWizard Plug-In Manager.
Figure 2–15. Offset Cancellation for Receiver Channels Option in the ALTGX_RECONFIG MegaWizard Plug-In Manager
When the device powers up, the dynamic reconfiguration controller initiates offset
cancellation on the receiver channel by disconnecting the receiver input pins from the
receiver data path. It also sets the receiver CDR into a fixed set of dividers to
guarantee a voltage controlled oscillator (VCO) clock rate within the range necessary
to provide proper offset cancellation. Subsequently, the offset cancellation process
goes through different states and culminates in the offset cancellation of the receiver
buffer and receiver CDR. After offset cancellation is complete, the user divider
settings are restored.
The dynamic reconfiguration controller sends and receives data to the transceiver
channel through the reconfig_togxb and reconfig_fromgxb signals. You must
connect these signals between the ALTGX_RECONFIG instance and the ALTGX
instance. You must also set the What is the number of channels controlled by the
reconfig controller? option in the Reconfiguration settings screen of the
ALTGX_RECONFIG MegaWizard Plug-In Manager. For more information, refer to
“Total Number of Channels Controlled by the ALTGX_RECONFIG Instance” on
page 2–35.
The Use 'logical_channel_address' port for Analog controls reconfiguration option
in the Analog controls screen of the ALTGX_RECONFIG MegaWizard Plug-In
Manager is not applicable for the receiver offset cancellation process.
1 If the design does not require PMA controls reconfiguration and uses optimum LE
resources, you can connect all the ALTGX instances in the design to a single dynamic
reconfiguration controller (ALTGX_RECONFIG instance).
HardCopy IV Device Handbook, Volume 3
© June 2009 Altera Corporation