NAT7210 Issues NRFD on ATN switch

[Rudie Biglaar]

Hi,

I'm having a problem with the NAT7210, used as a device, that I do not see on the NEC 7210.
When the NAT7210 is addressed to listen, it asserts NRFD after ATN has been de-asserted by the controller.
The only way to de-assert NRFD is to write a rhdf auxiliary command to the NAT7210. According to the documentation, this should only be necessary when an hdli auxiliary command has been issued.
The original NEC 7210 does not seem have this problem.

Am I doing something wrong? Or is possible to program the NAT7210 in such a way that it does not assert NRFD?

Thank you,

Rudie Biglaar

[theW]

Rudie,

It is my understanding of the 488 standard that the NRFD line being high means that the device is ready to accept data, which is what I would expect if I addressed a device as a listener. The controller would then put data on the DIO lines and then assert DAV. Is there a specific reason why you do not want NRFD to be high?

Scott

[Rudie Biglaar]

Scott,

Perhaps the use of 'asserted' was not so good in this situation.
What I mean is that NRFD stays low after the NAT7210 has been addressed as listener. When I send the bytes to do this, everything is OK. So, there is no problem in sending the sequence UNL, MTA0, MLA7. Every time NRFD goes low for a short time, and then goes high again. After MLA7 however, NRFD does not go high and I have to write a rrfd command to the chip to have it release NRFD.
I hope this makes it clearer.

Rudie