ST7DALIF2 datasheet(115/171 Pages) STMICROELECTRONICS

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ST7DALIF2

10-bit A/D converter (ADC)

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RAIN is the maximum recommended impedance for an analog input signal. If the impedance

is too high, this will result in a loss of accuracy due to leakage and sampling not being

completed in the alloted time.

18.3.4

A/D conversion

The analog input ports must be configured as input, no pull-up, no interrupt. Refer to

Section 12: I/O ports on page 61. Using these pins as analog inputs does not affect the

ability of the port to be read as a logic input.

In the ADCCSR register:

– Select the CS[2:0] bits to assign the analog channel to convert.

ADC conversion mode

In the ADCCSR register:

●

Set the ADON bit to enable the A/D converter and to start the conversion. From this

time on, the ADC performs a continuous conversion of the selected channel.

When a conversion is complete:

●

The EOC bit is set by hardware.

●

The result is in the ADCDR registers.

A read to the ADCDRH or a write to any bit of the ADCCSR register resets the EOC bit.

To read the 10 bits, perform the following steps:

Poll EOC bit

Read ADCDRL

Read ADCDRH. This clears EOC automatically.

To read only 8 bits, perform the following steps:

Poll EOC bit

Read ADCDRH. This clears EOC automatically.

18.4

Changing the conversion channel

The application can change channels during conversion.

When software modifies the CH[3:0] bits in the ADCCSR register, the current conversion is

stopped, the EOC bit is cleared, and the A/D converter starts converting the newly selected

channel.

18.5

Low power modes

Note:

The A/D converter may be disabled by resetting the ADON bit. This feature allows reduced

power consumption when no conversion is needed and between single shot conversions.

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