Notes On Use Of 10-Bit A/D Converter - Fujitsu F2MC-8FX Hardware Manual

23.7

Notes on Use of 10-bit A/D Converter

This section summarizes notes on using the 10-bit A/D converter.
Notes on Use of 10-bit A/D Converter
Notes on programmed setup
• 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.
• The CPU cannot return from interrupt processing if the interrupt request flag bit (ADC1: ADI) is 1 with
interrupt requests enabled (ADC2: ADIE = 1). Be sure to clear the ADI bit within the interrupt service
routine.
Note on interrupt requests
If A/D conversion is reactivated (ADC1: AD = 1) and terminated at the same time, the interrupt request
flag bit (ADC1: ADI) is set.
Error
As |V
CC
10-bit A/D converter and analog input power-on/shut-down sequences
Turn on the 10-bit A/D converter power supply (V
after turning on the digital power supply (DV
In addition, turn off the digital power supply (DV
bit A/D converter analog input (AN00 to AN07).
Be careful not to let the analog input exceed the voltage of the digital power supply when turning the 10-bit
A/D converter on and off.
Conversion time
The conversion speed of the A/D conversion function is affected by the clock mode, main-clock oscillation
frequency, and main-clock speed switching (gear function).
Example: Sampling time = CKIN
• The error max. 1CKIN-1MCLK may occur depending on the timing of A/D startup.
• Program the software satisfied with "sampling time" and "compare time" in A/D conversion of data
sheet.
-V | decreases, an error increases relatively.
SS
Compare time = CKIN x 10 (fixed value) + MCLK
Conversion time = A/D start processing time + sampling time + compare time
), and analog input (AN00 to AN07) at the same as or
CC
).
CC,
) either at the same time as or after turning off the 10-
CC
×
(ADC2: TIM1/0 setting)
CHAPTER 23 10-BIT A/D CONVERTER
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