Chapter 3: Cyclone IV Dynamic Reconfiguration 3–11
Dynamic Reconfiguration Controller Port List
November 2011 Altera Corporation Cyclone IV Device Handbook,
Volume 2
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
Tra nsmitte r o nl y 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.
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.
Figure 3–2. ALTGX and ALTGX_RECONFIG Connection for the Offset Cancellation Process
Note to Figure 3–2:
(1) This block is active during the offset cancellation process.
ALTGX
ALTGX_RECONFIG
reconfig_fromgxb[n..0]
reconfig_togxb[3..0]
busy
reconfig_clk
TX PCS
offset cancellation
circuit
TX PMA
RX PCS
RX PMA
+
CDR (1)
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