Increase the capacity by replacing the 47micro farad electrolytic capacitor

[araobp]

Arduino Uno restarts just after a command has been received from ESP-WROOM-02 via UART.

I have added another 47 micro farad capacitor to the output side of TA48M05F three-terminal regulator, and then I have observed that it have become stable.

So the solution is to replace the electrolytic capacitor on the output side of TA48M05F with another one (100, 200 or 470 micro farad) .

Rubycon 100 micro farad Rubycon 200 micro farad Rubycon 470 micro farad

[araobp]

100 micro farad is still unstable sometimes.

200 micro farad seems OK.

Buy the 200 or 470 micro farad capacitor. Maybe, 470 micro farad is better for stability.

[araobp]

I replaced the capacitor with 200 micro farad one, but the problem occurred again.

It seems that the sensor/actuator control sequence in the sketch for Arduino Uno is not good. The sequence should be (1) periodic task then (2) servo control, to avoid relatively high power consumption overlapping between the servo motor and the proximity sensors.

[araobp]

I modified the sketch but that did not solve the problem.

I observed with my oscilloscope that the voltage got down under 4V when PWM to the servo motor changed.

Try using another three-terminal regulator to supply Vcc to the servo motor.

[araobp]

I was wrong. Arduino Uno's Vin accepts 7 - 12 V, not 5V.

[araobp]

I supplied 1.5V * 7 = 10.5V to Arduino Uno's Vin.

• Arduino Uno TxD - (direct) -> ESP-WROOM-02 Rx worked.
• Arduino Uno TxD - registers to divide the voltage -> ESP-WROOM-02 Rx did not work.
• Arduino Uno TxD - FXMA108 -> ESP-WROOM-02 Rx worked.
• ESP-WROOM-02 Tx - (direct) -> Arduino Uno RxD worked.
• ESP-WROOM-02 Tx - FXMA108 -> Arduino Uno RxD did not work.

Servo motor control is perfect this time.

So all the problems have been fixed!

[araobp]

I use AA * 6 = 9V as a main power supply. In addition to that, I use a three-terminal regulator to convert 9V down to 3.3V.