ST72F324J6TCX データシートの表示（PDF） - STMicroelectronics

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ST72F324J6TCX

8-bit MCU for automotive, 3.8 to 5.5V operating range with 8 to 32 Kbyte Flash, 10-bit ADC, 4 timers, SPI, SCI

STMicroelectronics 

ST72324xx-Auto

On-chip peripherals

10.6.3 Functional description

The conversion is monotonic, meaning that the result never decreases if the analog input

does not increase.

If the input voltage (VAIN) is greater than VAREF (high-level voltage reference) then the

conversion result is FFh in the ADCDRH register and 03h in the ADCDRL register (without

overflow indication).

If the input voltage (VAIN) is lower than VSSA (low-level voltage reference) then the

conversion result in the ADCDRH and ADCDRL registers is 00 00h.

The A/D converter is linear and the digital result of the conversion is stored in the ADCDRH

and ADCDRL registers. The accuracy of the conversion is described in the Electrical

Characteristics Section.

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

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

c completed in the allotted time.

du A/D converter configuration

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

P Section 9: I/O ports. Using these pins as analog inputs does not affect the ability of the port

te to be read as a logic input.

le In the ADCCSR register:

so Select the CS[3:0] bits to assign the analog channel to convert.

Ob Starting the conversion

) - In the ADCCSR register:

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

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

du When a conversion is complete:

ro – the EOC bit is set by hardware

P– the result is in the ADCDR registers

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

leTo read the 10 bits, perform the following steps:

so 1. Poll the EOC bit.

Ob 2. Read the ADCDRL register

3. Read the ADCDRH register. This clears EOC automatically.

Note:

The data is not latched, so both the low and the high data register must be read before the

next conversion is complete. Therefore, it is recommended to disable interrupts while

reading the conversion result.

To read only 8 bits, perform the following steps:

1. Poll the EOC bit.

2. Read the ADCDRH register. This clears EOC automatically.

Doc ID 13841 Rev 1

133/193

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