8 Conclusion

This training demonstrates how to perform ADC conversion with the purpose of power optimization. The ADC result is expected to be printed through USART to a terminal. With the goal of reducing the current consumption, various techniques have been implemented to reduce the current consumption through the last four assignments such as:

• Configure the RTC overflow interrupt to start the ADC conversion and keep the CPU in Standby mode between conversions
• Disable digital input buffer on all I/O pins to avoid power supply current and configure the USART TX pin as input during no ADC data transmission period to avoid unnecessary current flow
• The ADC WCMP mode is used, instead of the ADC RESRDY interrupt, to make sure that only interested ADC data is sent to the terminal through USART
• Replace the RTC overflow interrupt routine by Event System to trigger the ADC conversion

In this training, the average current consumption improvement is significant by being reduced from 2.8 mA in assignment 1 and down to 1.13 μA in assignment 5. The peak current consumption has also been reduced from 2.8 mA to 170 μA or 690 μA depending on what scenario it belongs to. As shown, the current consumption gets reduced significantly when Standby Sleep mode is implemented and when optimization on I/O pins is performed. The ADC window compare mode further reduces the current consumption when the scenario with uninterested ADC result occurs. The last assignment with event system implementation reduces the current consumption, but not that significant. This is due to that the device still needs to wake up from the Sleep mode. It has been shown that the current consumption could be reduced significantly for an application with event system implementation when the device does not need to wake up from sleep.