Alt2gxb_reconfig

I thought I might post this on the forum to see if anybody has experience with this. I am currently implementing a design using a StratixIIGX (EP2SGX130). The design uses 16 of the 20 available serial transceivers. I have 16 SDI transmit video cores and 16 SDI receive video cores. All of the GXB transceiver instances in the design require dynamic reconfiguration.

My question relates to how the ALT2GXB_RECONFIG core works in this situation.

The Stratix I IGX Transceiver user guide (page 3-4) reads as follows (sorry it's long):

"The dynamic reconfiguration interface has the following signals:

■ reconfig_togxb[2:0] as an input signal bus

■ reconfig_fromgxb as an output signal from ALT2GXB instance.

reconfig_fromgxb is a transceiver block-based signal; for

example, if the number of the channels selected in ALT2GXB are:

&#9679; 0 < Channels < 4, then signal reconfig_fromgxb = 1 bit

&#9679; 4 < Channels < 8, then signal reconfig_fromgxb = 2 bits

&#9679; 8 < Channels < 12, then signal reconfig_fromgxb = 3 bits

&#9679; 12 < Channels < 16, then signal reconfig_fromgxb = 4 bits

&#9679; 16 < Channels < 20, then signal reconfig_fromgxb = 5 bits

After the dynamic reconfiguration option is enabled in the ALT2GXB

MegaWizard, you must set one more setting—the What is the dynamic

reconfig starting channel number? option. The dynamic reconfiguration

starting channel number setting range is from 0 - 156 in multiples of 4

(because the dynamic reconfiguration interface is per transceiver block).

This range of 0 - 156 is the logical channel address based purely on the

number of possible ALT2GXB instances.

To better understand how logical addressing works, consider the scenario

of 20 separate transmit and receive instances of the ALT2GXB

megafunction in a design and how to set the address of the starting

channel of each instance.

The first instance of a transmit and receive channel has the starting

channel number setting of 0. The second instance of a transmit and

receive channel has the starting channel number setting of 4. And so on.

The twentieth instance of the same configuration has the starting channe

number of 76.

Extending the same logic to the maximum possible instances case of 20

transmit-only and 20 receive-only configurations, targeted for a five

transceiver block Stratix II GX device, the maximum starting channel

number of the dynamic reconfiguration option is 156 (40 instances * 4)."

So this is the way I understand this. Every ALT2GXB instance uses 4 channel numbers. Each ALT2GXB instance must therefore have a starting channel number that is a multiple of 4. And of course, each ALT2GXB instance connected to an ALT2GXB_RECONFIG controller must have a different starting channel number. In my case, I have 32 ALT2GXB instances. So I assign each one a different starting channel number {0,4,8,12,...124}.

However, when I actually attempt to compile the project, the fitter produces an error which essentially says that it couldn't place the transmit and receive channels in the same GXB Control unit because the transmit and receive channels must have the same starting channel number. This to me flies in the face of what the documentation describes above.

Has anybody had any experience with this?

Thank you,

Jake