> ## Documentation Index
> Fetch the complete documentation index at: https://docs.lagerdata.com/llms.txt
> Use this file to discover all available pages before exploring further.

# ADC

> Read analog voltages from an ADC net

Read a single-ended analog voltage from an ADC net on a LabJack, MCC or similar acquisition device.

## Handle

```rust theme={null}
use lager::LagerBox;

let lager = LagerBox::from_env()?;
let adc = lager.adc("adc1");
```

The handle is cheap and does no I/O until you call a method. The box resolves and
validates the net name on every request, so a typo fails loudly rather than reading
the wrong pin.

## Methods

| Method   | Description                        |
| -------- | ---------------------------------- |
| `name()` | The net name this handle addresses |
| `read()` | Read the input voltage in volts    |

## Method Reference

### `name() -> &str`

The net name this handle was created with. Does not touch the network.

```rust theme={null}
assert_eq!(lager.adc("adc1").name(), "adc1");
```

### `read() -> Result<f64>`

Read the voltage present on the ADC input, in volts.

```rust theme={null}
let volts = adc.read()?;
println!("{volts:.4} V");
```

**Returns:** `f64` — the measured voltage in volts. Signed: a negative reading is a
real negative voltage, not an error.

## Examples

### Assert a rail came up

```rust theme={null}
use lager::LagerBox;

let lager = LagerBox::from_env()?;
let supply = lager.supply("supply1");
let vbat = lager.adc("adc1");

supply.set_voltage(3.3)?;
supply.enable()?;
std::thread::sleep(std::time::Duration::from_millis(200));

let measured = vbat.read()?;
assert!((measured - 3.3).abs() < 0.2, "rail is at {measured:.3} V, expected 3.3");
supply.disable()?;
```

### Poll a decaying rail

`read()` is a single cheap request, so polling in a loop is reasonable.

```rust theme={null}
use std::time::{Duration, Instant};

let start = Instant::now();
while start.elapsed() < Duration::from_secs(5) {
    let v = adc.read()?;
    if v < 1.0 {
        println!("rail collapsed after {:?}", start.elapsed());
        break;
    }
    std::thread::sleep(Duration::from_millis(50));
}
```

## Supported Hardware

| Instrument  | Channels   | Notes                  |
| ----------- | ---------- | ---------------------- |
| LabJack T7  | AIN0-AIN13 | 14 single-ended inputs |
| MCC USB-202 | CH0-CH7    | 8 single-ended inputs  |

## Notes

* Readings are **volts**, always. There is no unit selection on this net type.
* An unconnected input floats; a reading near zero on a disconnected pin is the
  instrument reporting noise, not a failure.
* Each ADC net is one channel. A device with fourteen inputs is fourteen nets.
* The box serializes access per physical instrument, so concurrent reads across
  several ADC nets on one device queue rather than interleave.