4507 datasheet(49/115 Pages) RENESAS

49 / 115 page

4507 Group

Rev.3.01

2005.02.04

page 49 of 111

REJ03B0107-0301

Fig. 51 Analog input external circuit example-1

Fig. 52 Analog input external circuit example-2

Notes for the use of A/D conversion 2

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.

When the operating mode of A/D converter is changed from the

comparator mode to A/D conversion mode with the bit 3 of regis-

ter Q1, note the following;

• Clear the bit 2 of register V2 to “0” (refer to Figure 50➀) to

change the operating mode of the A/D converter from the com-

parator mode to A/D conversion mode with the bit 3 of register

Q1.

• The A/D conversion completion flag (ADF) may be set when the

operating mode of the A/D converter is changed from the com-

parator mode to the A/D conversion mode. Accordingly, set a

value to the bit 3 of register Q1, and execute the SNZAD instruc-

tion to clear the ADF flag.

; (✕0✕✕2)

TV2A

; The SNZAD instruction is valid ........ ➀

; (0✕✕✕2)

TQ1A

; Operation mode of A/D converter is

changed from comparator mode to A/D

conversion mode.

SNZAD

NOP

✕ : this bit is not related to change the operation

mode of A/D converter.

Fig. 50 External 0 interrupt program example-3

Notes for the use of A/D conversion 3

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/

discharge noise is generated and the sufficient A/D accuracy

may not be obtained. Therefore, reduce the impedance or, con-

nect a capacitor (0.01

µF to 1 µF) to analog input pins (Figure

51).

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 52. In addition, test

the application products sufficiently.

Sensor

AIN

Apply the voltage withiin the specifications

to an analog input pin.

Sensor

AIN

About 1k

Ω

Notes for the use of A/D conversion 1

Note the following when using the analog input pins also for ports

P2 and P3 functions:

• Selection of analog input pins

Even when P20/AIN0, P21/AIN1, P30/AIN2, P31/AIN3 are set to pins

for analog input, they continue to function as ports P2 and P3 in-

put/output. Accordingly, when any of them are used as I/O port

and others are used as analog input pins, make sure to set the

outputs of pins that are set for analog input to “1.” Also, the port

input function of the pin functions as an analog input is unde-

fined.

• TALA instruction

When the TALA instruction is executed, the low-order 2 bits of

multaneously, the low-order 2 bits of register A is “0.”

4507 Datasheet(PDF) 49 Page - Renesas Technology Corp

4507 Datasheet(HTML) 49 Page - Renesas Technology Corp

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 ...More

Datasheet Download

Link URL