3.2.1 Overview

The ADC converts analog signals to digital values. The ADC has a 12-bit resolution and can convert up to 300 thousand samples per second (ksps). The input selection is flexible, and both single-ended and differential measurements can be done. An optional gain stage is available to increase the dynamic range for differential measurements.

The ADC can provide both signed and unsigned results. The ADC measurements can be started either by application software or an incoming event from another peripheral in the device. The ADC measurements can be started with predictable timing and without software intervention. When conversions are done, it is possible to use DMA to move ADC results directly to memory or peripherals. Both internal and external reference voltages can be used. An integrated temperature sensor is available for use with the ADC. The ADC can also measure the AV_CC/10 output and the band gap voltage. The ADC has a Compare function for accurate monitoring of user-defined thresholds with minimum software intervention required.

Figure 3-1. ADC Overview

The ADC may be configured for an 8- or 12-bit result. The minimum conversion time (propagation delay) reduces from 3.35 μs for a 12-bit result to 2.3μs for an 8-bit.

ADC conversion results are left or right adjusted with optional ‘1’ or ‘0’ padding, which eases calculation when the result is presented as a signed integer (signed 16-bit number).

PORTB has one ADC. Notation of this peripheral is ADCB.

Note: After the ADC is enabled, the first sample may deviate from the expected result. It is recommended to discard the first sample or accumulate several samples.