What is the fine-grained topic of the following text: The experiments in the Basic Analog and Digital textbook introduce PBASIC commands for A/D conversion with resistor/capacitor circuits, interfacing an ADC0831 8-bit A/D converter, scaling analog outputs into meaningful digital values, analyzing time-varying signals, and using PWM as analog output. Only return the topic.
Experiments on Analog to Digital Conversion in Basic Analog and Digital Textbook