NAT9914 TA bit not set

[nightpanda]

Dear Sir/Madam,

I'm tring to use NAT9914A as a GPIB controller to control other GPIB instrument (Agilent 33220A FG).

After sending out UNT+UNL+MLA+MTA, and shifting from active controller to standby mode, I can not send byte out from NAT9914A (BO bit not set).

What I did is:

1. initializer NAT9914A (GPIB address 21, set LCW and ATCT)

2. work in active controller mode (verified by reading ISR2)

3. Send UNT(5F), UNL(3F), MLA(2A), MTA(55) onto GPIB Bus (verified by logical analyzer)

4. shift into standby mode (ATN unasserted)

While now, I read ADSR and the value is 0x00. TA and TPAS bits are not set. Seems that NAT9914A has not accepted the MTA byte send by itself.

Is there anything I forgot to do before chaging into standby mode?

Thank you so much for helping me on this.

[nightpanda]

solved

[Steven_T]

Hello Nightpanda,

Would you mind sharing the solution to this problem?  It is possible that other users of this chip could run into the same issue.

Thanks,
Steven T.

[nightpanda]

well, it's my fault. I thougt I set the LCW bit. But acctually not. When you write the ACCR register, you must page in it first in AUXCR. Alway page in first!!!!

I spend two weeks on this issue~ almost killed myself