NAT7210BPD does not interrupt

[Collin M]

So you have one board on which you have tried the BPDs? Is there another board you can try? Also, can you switch back to the APD and see if it still works? The board may have been damaged while it was beign reworked. Do you have a socket you can install on the board to easily switch between the APD and BPD?

I haven't ruled out a problem with the NAT7210BPD yet but we have sold a substantial number of these without anyone else reporting this problem.

[Collin M]

Ely,

Can you configure the 7210 with only the clock speed info, clear reset, then see if it accepts command bytes. Check to see if it accepts command bytes from the controller in the PC.

The code should do the following:
send command 2 (chip reset)
set the clock (value 26H to ICR - 6MHz)
send command 0 (immediate execute power on)

If the 7210 then accepts commands then there is some problem with the other code that accesses the 7210.

Also, using the original configuration code, read the BSR when you are expecting an interrupt. Verify they match the state of the GPIB signals at the controller. If you are using NI-488 for the controller you can use the iblines func
tion. The 7210 should detect ATN and NDAC asserted when the controller in the PC is asserting attention to send command bytes.

If the 7210 does not accept command bytes then I think the interrupt issue is secondary to some other problem. The INT pin is probably functioning correctly but the 7210 is not ever internally generating an interrupt. The approach we should take is to get the 7210 to accept command bytes because it should almost always accept command bytes as long as pon is unasserted.

It sounds like it is fairly easy for you to change the code. At the end of your initialization routine can you add some code such that immediately after you send command 0 (execute power on) you wait 10 clock periods and then send command 0 again?

If the first command 0 did not complete for some reason the board would exhibit the symptoms you have described.

Can you also probe the control signals as well as the ATN signal between the transceiver and the NAT7210?

Collin

[elyshemer]

Collin,

Using an old GPIB410 card that we have, I was able to assert bus signals and observe 7210 responses.

Using the original initialization code, the 7210 did not respond to ATN being asserted and reading BSR showed recognition of changes in DAV, EOI and SRQ only. Using basic initialization code (as you recommended) the 7210 did respond to ATN by asserting NDAC, and all the bus signals were reflected correctly in the BSR register. This led me to suspect that the problem is with the setting of the ADM register.

Returning to the original initialization code, I've changed the value set to ADM from 31H to 01H (which is certainly not the correct value for our onfigura
tion). In this case, the 7210 recognized all BUS control lines and responded to ATN by asserting NDAC. I was even able to send the instrument a query and get a partial response.

This led to a further investigation of the transceivers control lines. We have found that the problem is with the T/R2 signal: with the APD chip T/R2 was able to pull the line down to a �0� (0.8V) but with the BPD chip it could not (2.4V).

Examining the board it was discovered that for some historical reason (versions with different type of transceivers) there was a long forgotten patch shorting T/R2 and T/R3. Removing the patch from the card resolved the whole thing. And this was a hardware issue after all (hey � I was not the culprit).

I would like to thank you for the great support you have given me, the quick responses and genuine effort to assist.

Ely