9.3.15 Interrupt Controller

The hardware-controlled PCM1860 and PCM1861 has the energysense signal detect as the default output on the INT pin. There are no other interrupt sources. The INT pin on the PCM1860 and PCM1861 is also used to put the device into power-down mode. Figure 44 shows the interrupt logic

Figure 44. Interrupt Logic

The software-controlled devices have multiple signals that can be mapped to the interrupt outputs. These include:

• Energysense (default)
• Secondary ADC controlsense interrupt
• Post PGA clip
• DIN toggle

The Interrupt controller has the following features

• The Interrupt sources can be filtered by the enable register (INT_EN).
• The Interrupt flags can be monitored by reading the status register (INT_STAT).
• The interrupt flags can be cleared by writing the status register.
• The polarity of the interrupt signal can be changed between active high, active low and Open Collector (High Impedance is pulled to GND) (INT_PLS).
• The pulse width of the interrupt signal can be changed between 1ms, 2ms, 3ms and 4ms.
• The interrupt controlled cannot remain asserted, the status bits can be sticky, but the interrupt pin itself has no hold function.

Using a combination of these features, as well as the interrupt sources, allows the PCM186x to alert a host microcontroller of an event, using whichever polarity signal required (pull high, pull low, Hi-Z open collector). The host controller can then communicate with the device to poll the interrupt flag register to find out what happened. Additional registers can then be read for more details. (For instance, which input triggered an energysense event.). From a register point of view, there is no difference between INT A, INT B and INT C logic, other than their signaling (positive, negative or open drain).