A semiconductor integrated circuit includes a bus, a CPU connected to the bus, a DAC having a digital input thereof connected to the bus, an ADC having a digital output thereof connected to the bus, a voltage generating circuit, a first switch configured to cause an electrical coupling between an analog input of the ADC and the voltage generating circuit to switch between a conductive state and a nonconductive state, and a second switch configured to cause an electrical coupling between an analog output of the DAC and the analog input of the ADC to switch between a conductive state and a nonconductive state.