EP4CE30F29C7N Datasheet, PDF (409/488 Pages) Altera Corporation – Cyclone IV Device Handbook, Volume 1

Chapter 3: Cyclone IV Dynamic Reconfiguration
Dynamic Reconfiguration Controller Port List
3–11
The Offset cancellation for Receiver channels option is automatically enabled in
both the ALTGX and ALTGX_RECONFIG MegaWizard Plug-In Managers for
Receiver and Transmitter and Receiver only configurations. It is not available for
Transmitter only configurations. For Receiver and Transmitter and Receiver only
configurations, you must connect the necessary interface signals between the
ALTGX_RECONFIG and ALTGX (with receiver channels) instances.
Offset cancellation is automatically executed once every time the device is powered
on. The control logic for offset cancellation is integrated into the dynamic
reconfiguration controller. You must connect the ALTGX_RECONFIG instance to the
ALTGX instances (with receiver channels) in your design. You must connect the
reconfig_fromgxb, reconfig_togxb, and necessary clock signals to both the
ALTGX_RECONFIG and ALTGX (with receiver channels) instances.
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. Subsequently, the offset cancellation process goes through
different states and culminates in the offset cancellation of the receiver buffer.
1 Offset cancellation process only occurs one time after power up and does not occur
when subsequent reconfig_reset is asserted. If you assert reconfig_reset after the
offset cancellation process is completed, the offset cancellation process will not run
again.
If you assert reconfig_reset upon power up; offset cancellation will not begin until
reconfig_reset is deasserted. If you assert reconfig_reset after power up but before
offset cancellation process is completed; offset cancellation will not complete and
restart only when reconfig_reset is deasserted.
Figure 3–2 shows the connection for offset cancellation mode.
Figure 3–2. ALTGX and ALTGX_RECONFIG Connection for the Offset Cancellation Process
reconfig_clk
ALTGX_RECONFIG
offset cancellation
circuit
reconfig_fromgxb[n..0]
ALTGX
reconfig_togxb[3..0]
TX PCS
TX PMA
busy
RX PCS
RX PMA
+ CDR (1)
Note to Figure 3–2:
(1) This block is active during the offset cancellation process.
1 The dynamic reconfiguration controller sends and receives data to the transceiver
channel through the reconfig_togxb and reconfig_fromgxb signals.
1 The gxb_powerdown signal must not be asserted during the offset cancellation
sequence.
November 2011 Altera Corporation
Cyclone IV Device Handbook,
Volume 2