11.3.4. ADC/DAC

○ CMSIS includes APIs for configuring ADC (Analog-to-Digital Converter) and DAC (Digital-to-Analog Converter) peripherals for reading analog inputs or generating analog outputs.

The ADC (Analog-to-Digital Converter) is a crucial component in embedded systems, particularly when working with sensors or other analog inputs. It converts analog signals, which are continuous in nature, into digital signals, which are discrete. This conversion allows the microcontroller to process real-world analog signals, such as temperature or light intensity. Conversely, the DAC (Digital-to-Analog Converter) does the reverse, taking digital values from the microcontroller and converting them back to an analog signal, useful for applications like generating sound or controlling voltages.

Imagine you are listening to music through a digital device. The music is stored as digital data (1s and 0s) inside the device. However, to hear the music through speakers, the device must convert this digital data back into analog sound waves. This process is similar to how ADC and DAC work in electronics; ADC allows the device to 'understand' analog inputs, while DAC translates digital outputs back to the analog world.

ADC1->CR2 |= ADC_CR2_ADON; // Enable ADC ADC1->SQR3 |= ADC_SQR3_SQ1_0; // Select channel

Enabling the ADC involves configuring the control register of the ADC peripheral. The line 'ADC1->CR2 |= ADC_CR2_ADON;' is a command that sets the ADC_ON bit in the ADC control register 2, which turns on the ADC hardware. This step is necessary before the ADC can be used to read any analog signals. Additionally, the second line of code 'ADC1->SQR3 |= ADC_SQR3_SQ1_0;' selects the specific channel from which the ADC will read the analog signal. In this case, it is selecting the first input channel for conversion. Each channel corresponds to a physical pin on the microcontroller where an analog sensor might be connected.

Consider using a thermometer that can measure temperature at different points. Before taking a measurement, you first need to turn on the thermometer (enabling the ADC). Then, you set it to read from a specific location, say the room temperature (selecting a channel). Once both steps are completed, you can collect data from that location.

ADC1->SQR3 |= ADC_SQR3_SQ1_0; // This selects channel

Once the ADC is enabled and the channel is selected, the ADC can begin converting the analog signal at the specified channel into a digital value. This process usually involves starting a conversion process, often done by writing to another control register. This robust setup allows the microcontroller to obtain data from the analog source effectively and repeatedly. The digital value obtained can then be processed for further actions, such as displaying the value on an LCD or making decisions based on the input.

Think of the ADC as a translator at a conference translating speeches from multiple languages. After turning on the translator device and selecting the language you want to listen to (the channel), you can seamlessly capture the essence of the speech (analog to digital conversion) and use the translated information for analysis or reporting.

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