Car Battery Level Monitor

The operation of this circuit can be simplified into three stages: reading battery voltage level, conversion, display battery level. The microcontroller, using its analog pin (AN00), reads the battery voltage level through the passive network composed of R1, R2 and C13. The diode MBRS120 serves as a reverse polarity protection to prevent damage to the microcontroller in case of reverse polarity connection. The resistors (R1 and R2) act as a voltage divider network stepping down the voltage coming from the battery for over-voltage protection and at the same time to equalize the maximum voltage of the battery to the reference voltage of the Analog-To-Digital (ATD) converter module of the microcontroller. The analog value read by the microcontroller will be converted into digital value. Based on that value, the microcontroller will display the battery level to the LCD screen. In order to accurately display the battery level, the ATD of the microcontroller must be calibrated with respect to the passive network sensor. The calibration process is done through software programming of the microcontroller.

The S912XHY128F0CLM microcontroller ATD converter module has 12 channel multiplexed analog inputs. Its ATD converter module can convert a single reading as fast as 3 microseconds. The ATD converter module high resolution feature (8/10 bit resolution) enables the S912XHY128F0CLM microcontroller to deliver a much more accurate display of the battery level used in a car automotive system.