HD404318 Datasheet, PDF (50/66 Pages) Hitachi Semiconductor – 4-bit HMCS400-series microcomputer

HD404318 Series
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 stop mode, 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 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 bit 1 of the A/D mode register as an analog pin will remain
pulled up.
A/D mode register 1 (AMR1: $019)
Bit
Initial value
Read/Write
Bit name
3
0
W
AMR13
2
1
0
0
W
W
AMR12 AMR11
0
0
W
AMR10
AMR12
0
1
AMR13
0
1
R3₂/AN₂ Mode Selection
R3₂
AN₂
R3₃/AN₃ Mode Selection
R3₃
AN₃
AMR10
0
1
AMR11
0
1
R3₀/AN₀ Mode Selection
R3₀
AN₀
R3₁/AN₁ Mode Selection
R3₁
AN₁
Figure 41 A/D Mode Register 1 (AMR1)
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