Fujitsu F2MC-8FX Hardware Manual page 439

Continuous activation
The settings shown in Figure 23.6-2 are required for continuous activation of the A/D conversion function.
Figure 23.6-2 Settings for A/D Conversion Function (Continuous Activation)
ADC1
ADC2
ADDH
: Bit used
×: Bit unused
1: Set to 1
0: Set to 0
When continuous activation is enabled, A/D conversion is activated at the rising edge of the selected input
clock to start the A/D conversion function. Continuous activation is stopped by disabling it (ADC2:EXT = 0).
Operations of A/D Conversion Function
This section details the operations of the 10-bit A/D converter.
1) When A/D conversion is started, the conversion flag bit is set (ADC1:ADMV = 1) and the selected
analog input pin is connected to the sample-and-hold circuit.
2) The voltage at the analog input pin is loaded into the sample-and-hold capacitor in the sample-and-hold
circuit during the sampling cycle. This voltage is held until A/D conversion has been completed.
3) The comparator in the control circuit compares the voltage loaded into the sample-and-hold capacitor
with the A/D conversion reference voltage, from the most significant bit (MSB) to the least significant
bit (LSB), and then sends the results to the ADDH and ADDL registers.
After the results have been completely transferred, the conversion flag bit is cleared (ADC1:ADMV =
0) and the interrupt request flag bit is set (ADC1:ADI = 1).
Notes:
• When the A/D conversion function is used, the contents of the ADDH and ADDL registers are
retained upon completion of A/D conversion. During A/D conversion, the values resulting from the
last conversion are loaded.
• Do not re-select the analog input channel (ADC1: ANS3 to ANS0) while the AD conversion
function is running, in particular, during continuous activation. Disable continuous activation
(ADC2: EXT = 0) before re-selecting the analog input channel.
• Starting the reset, stop, or watch mode stops the 10-bit A/D converter and initializes each register.
bit7 bit6 bit5
ANS3 ANS2 ANS1
AD8 TIM1 TIM0
- - -
CHAPTER 23 10-BIT A/D CONVERTER
bit4 bit3 bit2
ANS0 ADI ADMV
ADCK ADIE EXT
1
- - -
bit1 bit0
ADMVX AD
×
CKDIV1 CKDIV0
A/D converted value retained
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