Workflow

1.
Create an AC device instance struct, which will be associated with an Analog Comparator peripheral hardware instance.
```
static struct ac_module ac_instance;
```
Note: Device instance structures shall never go out of scope when in use.
2.
Define a macro to select the comparator channel that will be sampled, for convenience.
```
#define AC_COMPARATOR_CHANNEL   AC_CHAN_CHANNEL_0
```
3.
Create a new function configure_ac(), which will be used to configure the overall Analog Comparator peripheral.
```
void configure_ac(void)
```
4.
Create an Analog Comparator peripheral configuration structure that will be filled out to set the module configuration.
```
struct ac_config config_ac;
```
5.
Fill the Analog Comparator peripheral configuration structure with the default module configuration values.
```
ac_get_config_defaults(&config_ac);
```
6.
Initialize the Analog Comparator peripheral and associate it with the software instance structure that was defined previously.
```
ac_init(&ac_instance, AC, &config_ac);
```
7.
Create a new function configure_ac_channel(), which will be used to configure the overall Analog Comparator peripheral.
```
void configure_ac_channel(void)
```
8.
Create an Analog Comparator channel configuration structure that will be filled out to set the channel configuration.
```
struct ac_chan_config ac_chan_conf;
```
9.
Fill the Analog Comparator channel configuration structure with the default channel configuration values.
```
ac_chan_get_config_defaults(&ac_chan_conf);
```
10.
Alter the channel configuration parameters to set the channel to one-shot mode, with the correct negative and positive MUX selections and the desired voltage scaler.
```
ac_chan_conf.sample_mode      = AC_CHAN_MODE_SINGLE_SHOT;
ac_chan_conf.positive_input   = AC_CHAN_POS_MUX_PIN0;
ac_chan_conf.negative_input   = AC_CHAN_NEG_MUX_SCALED_VCC;
ac_chan_conf.vcc_scale_factor = 32;
```
Note: The voltage scalar formula is documented in description for ac_chan_config::vcc_scale_factor.

11.

Configure the physical pin that will be routed to the AC module channel 0.

struct system_pinmux_config ac0_pin_conf;
system_pinmux_get_config_defaults(&ac0_pin_conf);
ac0_pin_conf.direction    = SYSTEM_PINMUX_PIN_DIR_INPUT;
ac0_pin_conf.mux_position = CONF_AC_MUX;
system_pinmux_pin_set_config(CONF_AC_PIN, &ac0_pin_conf);

12.
Initialize the Analog Comparator channel and configure it with the desired settings.
```
ac_chan_set_config(&ac_instance, AC_COMPARATOR_CHANNEL, &ac_chan_conf);
```
13.
Enable the now initialized Analog Comparator channel.
```
ac_chan_enable(&ac_instance, AC_COMPARATOR_CHANNEL);
```
14.
Enable the now initialized Analog Comparator peripheral.
```
ac_enable(&ac_instance);
```