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 output 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.