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EN_AGC fails to unlock and restart the fast AGC.

Question asked by loktiing on Feb 7, 2018
Latest reply on Feb 9, 2018 by srimoyi

Hi all, I would like to ask some questions regarding ZSDR Comms – AD9361. I am currently working on the controlling the AD9361 fast attack AGC.

According to the AD9361 UG-570 Reference Manual (p.g. 46). Our baseband can use EN_AGC control pin to unlock and restart fast AGC (when it is already running) so that it can re-lock to a new gain index. We have RF front end gain that needs to be adjusted to command the reset of fast AGC.

EN_AGC control pin is available on our custom board and we also have software to pull the EN_AGC high. However, when we pull the pin high, nothing happens to fast AGC. We do not see any of the following takes effect through the dedicated control out pins:

1) Gain Lock goes low;

2) Rx Gain changes;

3) AGC state changes;

Prior to this we have AGC that works fine in unlocking and locking the gain depending on various overloads conditions.

We followed UG-570 to set bits in 0x0FB[D6], 0x111[D5] and clear bits in 0x110[D6:D5] so that the gain is set maximum once AGC restarts. So the question is why pulling EN_AGC high have no effect on fast AGC.

Kindly advise if I have missed out any steps in configuring the AD9361 fast AGC.