215
/
838
Nations Technologies Inc.
Tel
:
+86-755-86309900
:
Address: Nations Tower, #109 Baoshen Road, Hi-tech Park North.
Nanshan District, Shenzhen, 518057, P.R.China
trigger signal is generated. Next trigger will continue to convert 1 channel from the point where the previous
conversion stopped until all channels of the injection sequence are converted, and the end of conversion flag bit will
also be set to 1. When the conversion of all channels in the conversion sequence is completed, when the next trigger
signal occurs ,the conversion starts from the first channel of the injection sequence again.
Only one of injection conversion and regular conversion can be set to discontinuous mode at the same time, and the
automatic injection function and discontinuous mode cannot be set at the same time.
Calibration
In order to reduce the error, the ADC will have a built-in self-calibration mechanism. Before the A/D conversion, this
self-calibration mechanism is used to calculate a calibration factor on each capacitor. Errors due to changes in the
internal capacitor bank during conversion are eliminated by this calibration factor. The application program sets the
ADC_CTRL2.ENCAL bit to 1 to start self-calibration. During the calibration, the ADC_CTRL2.ENCAL bit remains
1. After the calibration, the ADC_CTRL2.ENCAL bit is cleared by hardware, and then the A/D conversion starts.
Note:
1.
It is recommended to perform a calibration after each power-on. If the ADC has been converted and is in
continuous conversion mode, the calibration operation cannot be completed..
2.
The default is single-end calibration, and for differential automatic calibration, you must set
ADC_CTRL3.CALDIF to 1. Then write 1 to ADC_CTRL2.ENCAL bit and wait for calibrationto complete
(ADC_CTRL2.ENCAL bit will clear 0 automatically after calibration).
Figure 9-7 Calibration sequence diagram
Data aligned
There are two alignment methods for data storage after conversion: left-aligned and right-aligned. The alignment can
be set by the ADC_CTRL2.ALIG bit. ADC_CTRL2.ALIG = 0 is right-aligned, as shown in
ADC_CTRL2.ALIG = 1 is left-aligned, as shown in
For injection sequence , the SYM bit is the extended sign value, and the data stored in the register is the conversion
result minus the user-defined offset in the ADC_JOFFSETx register, so the result can be a negative value; for regular
sequence , there is no need to subtract offset value.
ENCAL
CLK
Normal ADC Conversion
ADC
Conversion
ENCAL is set to 0 by hardware
Calibration (t
ENCAL
)
`