4509 Datasheet, PDF (66/142 Pages) Renesas Technology Corp – SINGLE-CHIP 4-BIT CMOS MICROCOMPUTER

4509 Group
22 _{Notes for the use of A/D conversion 1}
• TALA instruction
When the TALA instruction is executed, the low-order 2 bits of reg-
ister AD is transferred to the high-order 2 bits of register A,
simultaneously, the low-order 2 bits of register A is “0.”
• Do not change the operating mode (both A/D conversion mode and
comparator mode) of A/D converter with the bit 3 of register Q1
while the A/D converter is operating.
• Clear the bit 2 of register V2 to “0” to change the operating mode
from the comparator mode to A/D conversion mode.
• The A/D conversion completion flag (ADF) may be set when the
operating mode of the A/D converter is changed from the compara-
tor mode to the A/D conversion mode. Accordingly, set a value to
the bit 3 of register Q1, and execute the SNZAD instruction to clear
the ADF flag.
23 _{Notes for the use of A/D conversion 2}
Each analog input pin is equipped with a capacitor which is used to
compare the analog voltage. Accordingly, when the analog voltage
is input from the circuit with high-impedance and, charge/dis-
charge noise is generated and the sufficient A/D accuracy may not
be obtained. Therefore, reduce the impedance or, connect a ca-
pacitor (0.01 µF to 1 µF) to analog input pins (Figure 60).
When the overvoltage applied to the A/D conversion circuit may
occur, connect an external circuit in order to keep the voltage
within the rated range as shown the Figure 61. In addition, test the
application products sufficiently.
Sensor
AIN
LA 8
TV2A
LA 0
TQ1A
SNZAD
NOP
; (✕0✕✕2)
; The SNZAD instruction is valid ........ ➀
; (0✕✕✕2)
; Operation mode of A/D converter is
changed from comparator mode to A/D
conversion mode.
✕ : this bit is not related to change the operation
mode of A/D converter.
Fig. 61 External 0 interrupt program example-3
Apply the voltage withiin the specifications
to an analog input pin.
Fig. 62 Analog input external circuit example-1
Sensor
About 1kΩ
AIN
Fig. 63 Analog input external circuit example-2
24 _QzROM
(1) Be careful not to apply overvoltage to MCU. The contents of
QzROM may be overwritten because of overvoltage. Take care
especially at turning on the power.
(2) As for the product shipped in blank, Renesas does not perform
the writing test to user ROM area after the assembly process
though the QzROM writing test is performed enough before the
assembly process. Therefore, a writing error of approx.0.1 %
may occur. Moreover, please note the contact of cables and for-
eign bodies on a socket, etc. because a writing environment may
cause some writing errors.
25 _{Notes On ROM Code Protect}
(QzROM product shipped after writing)
As for the QzROM product shipped after writing, the ROM code
protect is specified according to the ROM option setup data in the
mask file which is submitted at ordering.
The ROM option setup data in the mask file is “0016” for protect
enabled or “FF16” for protect disabled.
Note that the mask file which has nothing at the ROM option data
or has the data other than “0016” and “FF16” can not be accepted.
Rev.1.02 2006.12.22 page 66 of 140
REJ03B0147-0102