Analog Devices ADRV9005 Reference Manual page 189

Reference Manual
RECEIVER GAIN CONTROL
With power detection, the gain change can only happen at the expiration of the gain update counter, which is typically set in the order of
hundreds of microseconds or milliseconds. However, power detectors are usually more stable and unlikely to cause frequent gain changes. In
addition, it can provide tighter control of the signal level by using a set of inner and outer thresholds compared to the peak detector.
It is highly recommended to use peak detection, especially for fast gain control.
Manual Gain Control (MGC)
The gain control block applies the settings from the selected gain index in the gain table. In the MGC mode, the baseband processor is in
control of selecting the gain index. There are two options: API command (ADI_ADRV9001_RX_GAIN_CONTROL_MODE_SPI) and pin control
(ADI_ADRV9001_RX_GAIN_CONTROL_MODE_PIN). By default, if MGC is chosen, the part is configured for an API command.
In the API command mode, select a gain index in the gain table through the API function adi_adrv9001_Rx_Gain_Set(). The gain index
selected for a channel is read back through the API function adi_adrv9001_Rx_Gain_Get().
The pin control MGC mode is useful for the real time control of gain. The API command adi_adrv9001_Rx_GainControl_PinMode_Config-
ure() is used to properly configure this mode. In this mode, out of 16 digital DGPIO pins, two pins per receiver are used, one increasing and the
other decreasing the gain table index. Specify both the maximum and minimum gain index as well as the increment and decrement step size (in
the range of 0 to 7 gain table indices). Apply a pulse to the relevant DGPIO pin to trigger an increment or decrement in gain, as shown in
169. Hold this pulse high for at least two AGC clock cycles for a reliable detection of the rising edge to trigger the gain change. The following
defines the configuration data structure for this mode.
typedef struct adi_adrv9001_RxGainControlPinCfg
{
uint8_t minGainIndex; //Minimum gain index. Must be >= gainTableMinGainIndex and < maxGainIndex
uint8_t maxGainIndex; //Maximum gain index. Must be > minGainIndex and <= gainTableMaxGainIndex
uint8_t incrementStepSize; //Number of indices to increase gain on rising edge on incrementPin (Range:
0 to 7)
uint8_t decrementStepSize; //Number of indices to decrease gain on rising edge on decrementPin (Range:
0 to 7)
adi_adrv9001_GpioPin_e incrementPin;// A rising edge on this pinincrements gain by incrementStepSize.
adi_adrv9001_GpioPin_e decrementPin; //A rising edge on this pin decrements gain by decrementStepSize.
} adi_adrv9001_RxGainControlPinCfg_t
In the MGC mode, to properly control the gain, optionally retrieve the status of peak detectors and the power detector in the device through
a set of DGPIO pins (this can also be done in the AGC mode for observation). To make sure that the status information from the signal
detectors is meaningful, it is important to first enable and configure the signal detectors properly, which is done through the API command. The
feedback information is configured into two modes; the peak detect and peak/power detect modes. In the peak detect mode, the overrange
and underrange conditions of both the APD and HB detectors are provided through the DGPIO pins. In the peak and power detect mode, the
overrange and underrange conditions of the power detector and the overrange and underrange conditions of the APD are provided through the
DGPIO pins.
Table 81 describes the feedback configuration and the bitfield definition and position. For example, when it is configured in peak mode, connect
to a set of DGPIO pins to retrieve all the APD and HB detector status. Note that the DGPIO pins are selected from pin 0 to pin 15, and two
analog.com
Figure 169. MGC Pin Mode: DGPIO (a to d) Represent Any of DGPIO[0:15]
ADRV9001
Figure
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