M34282M1-XXXGP View Datasheet(PDF) - Renesas Electronics

Part Name

Description

Manufacturer

M34282M1-XXXGP

SINGLE-CHIP 4-BIT CMOS MICROCOMPUTER

Renesas Electronics 

4282 Group

RESET FUNCTION

The 4282 Group has the power-on reset circuit, though it does

not have RESET pin. System reset is performed automatically

at power-on, and software starts program from address 0 in page

0.

In order to make the built-in power-on reset circuit operate

efficiently, set the voltage rising time until VDD= 0 to 2.2 V is

obtained at power-on 1ms or less.

f(XIN)

Internal reset signal

“H”

“L”

Fig. 18 Reset release timing

f(XIN) 16384 pulses

Software operation starts

(address 0 in page 0)

VDD

Internal reset signal

Power-on reset circuit

Voltage drop detection circuit

Watchdog timer output

Power-on reset circuit

output voltage

Reset state

Internal reset signal

Fig. 19 Power-on reset circuit example

(1) Internal state at reset

Table 6 shows port state at reset, and Figure 20 shows internal

state at reset (they are retained after system is released from

reset).

The contents of timers, registers, flags and RAM except shown

in Figure 20 are undefined, so set the initial value to them.

(2) Note on power-on reset

Under the following condition, the system reset occurs by the

built-in the power-on reset circuit of this product;

- when the supply voltage (VDD) rises from 0 V to 2.2 V, within 1 ms.

Also, note that system reset does not occur under the following

conditions;

- when the supply voltage (VDD) rises from the voltage higher

than 0V, or

- when it takes more than 1 ms for the supply voltage (VDD) to

rise from 0 V to 2.2 V.

Power-on

Reset released

Table 6 Port state at reset

Name

State at reset

D0–D3 High impedance state

D4–D7 High impedance state (Pull-down transistor OFF)

G0–G3 High impedance state (Pull-down transistor OFF)

E0, E1 High impedance state (Pull-down transistor OFF)

CARR “L” output

Rev.1.33 Mar 18, 2004 page 17 of 67

Share Link: