We have an implementation of the AD9361 on a custom board using the NOOS software and a custom FGPA build. Almost every feature works, but I'm having trouble using the Hybrid Slow Attack Gain Control. Manual Gain Control, Slow Attack Gain Control, and Fast Attack Gain Control all work as expected. This includes using CTRL_IN2 line from the FPGA to that AD9361 to change the gain in Manual Gain Control mode. However, when I set the Init_Param in the NOOS driver to Hybrid Slow Attack (gc_rx1_mode = 3 and gc_rx2_mode = 3), toggling CTRL_IN2 does not cause the Gain to be re-evaluated.
I have verified:
The data out signal (I and Q) is seen in the BBP but the signal is clipped. The gain is too high.
SPI 0x03 both Rx1 and Rx2 are enabled.
SPI 0x04 the correct input is enabled
SPI 0xFA = 0xFF
I have tried all possible combinations of the following:
SPI 0xFB setting and clearing D6 for Gain Unlock Control
EN_AGC set and clear
What is the next thing that I should try? I know that CTRL_IN2 works. The AD9361 is working as expected except that I can not us the Hybrid Slow Attack mode to allow external control to trigger the AGC. I would like to give the BBP control of when the AGC is triggered.