HD404358 Datasheet, PDF (78/102 Pages) Renesas Technology Corp – microcomputer has an A/D converter,

HD404358 Series
A/D data register (lower digit) (ADRL: $017)
Bit
Initial value
Read/Write
Bit name
3
0
R
ADRL3
2
0
R
ADRL2
1
0
R
ADRL1
0
0
R
ADRL0
Figure 69 A/D Data Register Lower Digit (ADRL)
A/D data register (upper digit) (ADRU: $018)
Bit
Initial value
Read/Write
Bit name
3
1
R
ADRU3
2
0
R
ADRU2
1
0
R
ADRU1
0
0
R
ADRU0
Figure 70 A/D Data Register Upper Digit (ADRU)
Notes on Usage
• Use the SEM or SEMD instruction for writing to the A/D start flag (ADSF)
• Do not write to the A/D start flag during A/D conversion
• Data in the A/D data register during A/D conversion is undefined
• Since the operation of the A/D converter is based on the clock from the system oscillator, the A/D
converter does not operate in stop mode. In addition, to save power while in these modes, all current
flowing through the converter’s resistance ladder is cut off.
• If the power supply for the A/D converter is to be different from V_CC, connect a 0.1-µF bypass capacitor
between the AV_CC and AV_SS pins. (However, this is not necessary when the AV_CC pin is directly
connected to the V_CC pin.)
• The contents of the A/D data register are not guaranteed during A/D conversion. To ensure that the A/D
converter oparates stably, do not execute port output instructions during A/D convention.
• The port data register (PDR) is initialized to 1 by an MCU reset. At this time, if pull-up MOS is selected
as active by bit 3 of the miscellaneous register (MIS3), the port will be pulled up to V_CC. When using a
shared R port/analog input pin as an input pin, clear PDR to 0. Otherwise, if pull-up MOS is selected by
MIS3 and PDR is set to 1, a pin selected by A/D mode register 1 or 2 (AMR1 or AMR2) as an analog
pin will remain pulled up (figure 71).
76