3–20
Altera Corporation
Stratix II GX Device Handbook, Volume 2
October 2007
Channel and PMA Controls Reconfiguration
ALT2GXB Instances and ALT2GXB_RECONFIG Instance
Connections:
■
Connect the
reconfig_fromgxb
signal from the ALT2GXB
instance to the same signal in the
ALT2GXB_RECONFIG
instance.
■
Connect the
reconfig_togxb
signal from the
ALT2GXB_RECONFIG instance to the same signal in the ALT2GXB
instance.
Channel and
PMA Controls
Reconfiguration
The write transaction of the controller is initiated on the assertion of the
write_all
signal. In PMA reconfiguration mode, the
write_all
signal writes the current state of all the selected input signals into the
ALT2GXB instance channels. The write transaction involves the
following sequence:
1.
Read the control analog registers (read before write).
2.
Write the current state of input signals of all channels into control
registers.
3.
Update the output control signals (optional read control ports if any
of the read control ports are enabled).
If you select the read control port, the
data_valid
signal is enabled.
Reading and updating all the output control signals is part of the write
transaction. Therefore, the
data_valid
signal is asserted only when the
write transaction is finished (
busy
signal is low) and all the output
control ports are updated with the new data. When a write transaction is
initiated and a set of values for the selected analog settings is being
written, you cannot change the input values of the control ports until the
transaction is completed. Otherwise, the results are unpredictable. The
dynamic reconfiguration controller asserts the
busy
signal when you
initiate a read or write transaction and is deasserted after the operation is
complete.
1
Simultaneous write and read transactions are not allowed.
Figure 3–5
illustrates a write transaction for a transmit analog setting V
OD
(
tx_vod
). The waveform shows a typical write transaction initiated by
the pulsing of the
write_all
signal and also shows the behavior of the
status signals
busy
and
data_valid
. Set the
reconfig_mode_sel
signal to
000
to reconfigure the analog settings of a transceiver channel.
Содержание Stratix II GX
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