EM357-RTR datasheet(176/240 Pages) ETC2

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EM351 / EM357

10 ADC (Analog to Digital Converter)

The EM35x ADC is a first-order sigma-delta converter with the following features:

Resolution of up to 14 bits

Sample times as fast as 5.33 µs (188 kHz)

Differential and single-ended conversions from six external and four internal sources

Two voltage ranges (differential): -VREF to +VREF, and –VDD_PADS to +VDD_PADS

Choice of internal or external VREF

internal VREF may be output to PB0 or external VREF may be derived from PB0

Digital offset and gain correction

Dedicated DMA channel with one-shot and continuous operating modes

Figure 10-1 shows the basic ADC structure.

Figure 10-1. ADC Block Diagram

While the ADC Module supports both single-ended and differential inputs, the ADC input stage always operates

in differential mode. Single-ended conversions are performed by connecting one of the differential inputs to

VREF/2 while fully differential operation uses two external inputs.

Note:

The regulator input voltage, VDD_PADS, cannot be measured using the ADC, but it can be measured

through Ember software.

10.1

Setup and Configuration

To use the ADC follow this procedure, described in more detail in the next sections:

Configure any GPIO pins to be used by the ADC in analog mode.

Configure the voltage reference (internal or external).

Set the offset and gain values.

If using DMA, reset the ADC DMA, define the DMA buffer, and start the DMA in the proper transfer mode.

10-1

120-035X-000D

Preliminary

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