USB to Serial / TTL Adapter to Program ATmega328p (w/out DTR Pin!)




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This will help you upload code to an atmega328p for your standalone arduino project using USB to serial / TTL adapter!

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Step 1:

First let’s see if the adapter’s working.

Plug in the adapter >> Open Arduino IDE >> Select the proper COM port >> Open Serial Monitor >> then type in “Hello World”, it should print “Hello World” in the monitor, if not something is wrong


Step 2: Fixing the Adapter's Driver

Device Manager >> Ports (COM & LPT)

If there is a yellow triangle next to “Prolific USB-to-Serial Comm Port”, that means correct driver version is not installed.

(Click this for more info)

Uninstall your existing driver (Control Panel >> Uninstall a program)

Download driver

Then install and done!

Do step 1 again to see if the adapter is now working

Step 3: Make the Necessary Wirings

For atmega328p on a breadboard, make the following connections (also, add an LED in series with a 100 ohm resistor on atmega328p pin 19/digital pin 13 for testing later)


1. Pushbutton (normally open)

2. 1 10kohm resistor

3. 2 22pF ceramic capacitors

4. Atmega328p

5. 16 MHz crystal oscillator

Step 4: Atmega328p Pinout

Step 5: Uploading Codes

For uploading code:

1. First make the following connections with the USB to Serial/TTL Adapter

USB to Serial/TTL Adapter >>>Atmega328p

5V >>> 5V rail

GND >>> GND rail

TXD >>> Pin 2 / RX pin

RXD >>> Pin 3 / TX pin

2. Open Arduino IDE >> File >> Examples >> Basics >> Blink

3. Press the pushbutton >> Hit upload

4. Keep on pressing if it says “Compiling sketch…”

5. Release the button as soon as it says “Uploading…”

6. Done!

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    3 Discussions


    5 weeks ago

    Not working.
    Error :- programmer is not responding


    Reply 10 months ago

    It cannot work easily, because this USB to Serial converter doesn't have the DTR pin. You have to push the reset button just before the compiling ends, and release it just after the "Uploading..." message appears. Not so comfortable, IMHO.
    Instead, you can buy a CP2104 USB to Serial converter, connect pins as explained above and the DTR pin to the reset pin of the ATMega328. In this way the reset comes directly from Arduino IDE.