SWCU192 November 2021 CC1312R7 , CC1352P7 , CC2652P7 , CC2652R7
The battery monitor is a 7-bit SAR-like ADC running at 125 kHz that performs alternate measurements of the supply voltage and the temperature sensor. When the battery monitor has settled on its first measurement, it stops working in SAR mode and starts linear tracking of voltage and temperature. A small digital core transforms these measurements to voltage and temperature in °C, which are read directly from the AON_BATMON:BAT and AON_BATMON:TEMP registers.
When a change in supply voltage or temperature is detected, the Battery Monitor will solely track the voltage until it has settled on a new constant level. The resolution of the ADC and the 125 kHz clock speed will limit the Battery Monitors capability of measuring voltage spikes. Due to the Battery Monitor not only alternating between temperature and battery voltage, but also between checking if there has been a positive or negative change since last read, there can be a delay of 6 clock cycles between a voltage dip and the time when the ADC notices that the temperature or voltage has changed. Due to the prioritization of voltage tracking upon detection of voltage changes, temperature changes might be detected with more delays if the voltage is also changing at the same time. This is important to keep in mind because the Battery Monitor is designed to measure the battery voltage; it is not designed to measure voltage spurs due to short periods of higher current consumption.
The module also includes an event register, AON_BATMON:EVENT, that includes six events:
These events must be cleared by writing to the AON_BATMON:EVENT register. The events will be asserted again if the conditions for the events are met (assertion of the new events takes precedence over the clearing of the events). In addition to the individual events listed previously, the battery monitor module has a combined event that is connected to the CPU as an interrupt line. The mask register, AON_BATMON:EVENTMASK, can be used to select which of the events in AON_BATMON:EVENT contribute to the combined event. These events are connected to the AON event fabric. For details, see Section 6.