ST7LITE49M datasheet(130/188 Pages) STMICROELECTRONICS

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On-chip peripherals

ST7LITE49M

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Configuring the A/D conversion

The analog input ports must be configured as input, no pull-up, no interrupt (see Section 10:

I/O ports). Using these pins as analog inputs does not affect the ability of the port to be read

as a logic input.

To assign the analog channel to convert, select the CH[2:0] bits 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 the 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.

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.

11.5.4

Low power modes

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.

11.5.5

Interrupts

None.

Table 53.

Effect of low power modes on the A/D converter

Mode

Description

Wait

No effect on A/D Converter

Halt

A/D Converter disabled.

After wake up from Halt mode, the A/D Converter requires a stabilization time

tSTAB (see Electrical Characteristics) before accurate conversions can be

performed.

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