ZHCSIM2D June 2010 – August 2021 PCM9211
PRODUCTION DATA
The PCM9211 has the ability to monitor audio inputs, which can be used to trigger interrupt outputs on port INT1. The ADC has a level monitor that can be set so that INT1 can be triggered whenever a specific level (referenced to 0dBFS) is crossed. A block diagram for this function is shown in Figure 7-8.
Operation of the level detect circuitry is shown in Figure 7-9. The ADC level detect is flagged when either ADC channel goes high. The flag is cleared when Register 2Dh is read.
The trigger threshold for the ADC can be configured at four different levels below full scale using the ADLVLTH[1:0] bits in Register 2Eh. The output is post-ADC volume control, allowing finer gain steps to be configured by changing the ADC volume control.
In a typical application, this level change is done as the system moves into standby, and reset back to 0dB attenuation when the system wakes up.
The output of this comparator circuit can be ORed along with the INT1 interrupt that is sourced. When the INT1 interrupt is flagged, then the INT1 output register can be read by the host controller.