m3819 Renesas Electronics Corporation., m3819 Datasheet - Page 184

• Manufacturer Part Number: m3819
• Description: Mitsubishi 8-bit Single-chip Microcomputer 740 Family / 38000 Series
• Manufacturer: Renesas Electronics Corporation.

3. APPENDIX
170
3.1 Notes on use
3.1.2 Notes on the FLD controller and the serial I/O automatic transfer function
3.1.3 Notes on the A-D converter
3.1.1 Notes on Interrupts
When using the FLD controller function and the serial I/O automatic transfer function, set the system clock to the high-
speed mode or the middle-speed mode.
<Note 1>
Make the signal source impedance for analog input low, or equip an analog input pin with an external capacitor of
0.01 F to 1 F. Further, be sure to verify the operation of application products on the user side.
Reason
An analog input pin includes the capacitor for analog voltage comparison. Accordingly, when signals from signal
source with high impedance are input to an analog input pin, charge and discharge noise generates. This may cause
the A-D comparison precision to be worse.
<Note 2>
Pins AV
<Note 1>
For the products able to switch the external interrupt
detection edge, switch it as the following sequence.
Reason
The interrupt circuit recognizes the switching of the
detection edge as the change of external input signals.
This may cause an unnecessary interrupt.
<Note 2>
Fix the bit 7 of the interrupt control register 2 to “0”.
Figure 3.1.1 shows the structure of the interrupt control
register 2.
AV
AV
CC
SS
: Connect to the V
CC
: Connect to the V
and AV
SS
are A-D converter power source pins. Connect them as following :
SS
CC
line which is the analog system
line which is the analog system
3819 Group USER’S MANUAL
Fig. 3.1.1 Structure of interrupt control register 2
Clear an interrupt enable bit to “0” (interrupt disabled)
Clear an interrupt request bit to “0” (no interrupt requ-
est issued)
Set the interrupt enable bit to “1” ( interrupt enabled )
b7
0
NOP (one or more instructions)
Switch the detection edge
3.1 Notes on use
MITSUBISHI MICROCOMPUTER
b0
Interrupt control register 2
Address 003F
Interrupt control bits
Not used
Fix this bit to “0”
3819 Group
16