HC4GX15 Datasheet, PDF (519/668 Pages) Altera Corporation – HardCopy IV Device Handbook

Chapter 2: HardCopy IV GX Dynamic Reconfiguration
2–61
PMA Controls Reconfiguration
PMA Control Ports Used in a Read Transaction
The width of the PMA control ports for a read transaction are always separate for each
channel (the same as the PMA control ports, as explained in “Use the Same Control
Signal for All Channels Option Enabled” on page 2–57).
Write Transaction
Because the PMA controls of all channels are written, if you want to reconfigure a
specific channel connected to the ALTGX_RECONFIG instance, set the new value to
the corresponding PMA control port of the channel under consideration and retain
the previously stored values in the other active channels using a read transaction prior
to this write transaction.
For example, assume that the number of channels controlled by the
ALTGX_RECONFIG is 2, tx_vodctrl in this case is 6 bits wide. The
tx_vodctrl[2:0] corresponds to channel 1, and similarly, tx_vodctrl[5:3]
corresponds to channel 2. Follow these steps:
1. If you want to dynamically reconfigure the PMA controls of only channel 2 with a
new value, first perform a read transaction to retrieve the existing PMA control
values from tx_vodctrl_out[5:0]. Take tx_vodctrl_out[2:0] and
provide this value in tx_vodctrl[2:0] to the write in channel 1. By doing so,
channel 1 gets overwritten with the same value.
2. Perform a write transaction. This ensures that the new values are written only to
channel 2, while channel 1 remains unchanged.
© June 2009 Altera Corporation
HardCopy IV Device Handbook, Volume 3