Datasheet

11.12. Audio Jack Detect
The microphone bias output pin HBIAS provide a low noise reference voltage suitable for biasing electrets
type microphones and the associated external resistor biasing network. Hbias is designed to drive headset
microphone, and a bias current detect function is provided for external accessory detection by measuring
the Hbias current. In some application, it's used to detect the insertion/removal of a audio jack and the
button press. These events will cause a significant change in bias current flow, which can be detected and
used to generate a signal to the processor.
When HBIAS current detect is enabled, 5 bit ADC will send out sample data at 16/32/64/128Hz clock rate.
Digital logic trigger an interrupt event controlled by register setting when the data is changed.
The digital circuit generate five IRQ signals that can be disabled by register, the data from ADC can be read
from register HMIC_STATUS Bit12:8.
IRQ Timing Diagram:
Figure 31 HBIAS Detect IRQ Timing Diagram