USB To Serial Interface


FT232RL USB to Serial breakout board

You can program the processor directly from the Arduino IDE. All you need is a TTL serial connection. The FT232RL USB to Serial breakout board is ideal for this. Now that we are using the modified Arduino UNO bootloader, we have also included a 0.1uF capacitor in the kit which allows for the auto-reset functionality of the UNO boards. This capacitor goes between the DTR pin on the FT232RL USB to Serial board and the Reset pin on the ATmega328.


FT232RL connected to Atmega328

Just connect the ATMega328 RX (pin 2) to TX on the breakout board, the ATMega328 TX (pin 3) to RX on the breakout board, connect the 0V and you are connected

NOTE: Do NOT connect the ATMega328 TX and RX pins directly to an actual PC serial port The voltages are incompatable and you may damage the chip

If you have a PC Serial Port (or USB to serial port cable) you can use this directly without the need for the breakout board with the addition of two transistors and a few resistors with the following modification.


Schematic of Atmega328

Programming the ATmega328

Once you have your serial connection setup you can program the ATmega328 directly from the Arduino IDE. Firstly, you must select the Arduino UNO as the board (or if using the 8MHz chip Arduino Pro or Pro Mini (3.3V, 8 MHz) w/ ATmega328)

Next, press the upload button in the Arduino IDE, and wait until you get the successfully compiled message (below). As soon as the message appears, press the reset button on your board to force the bootloader to reset.


Click the upload button

Your program should then be loaded and will start running


Uploading program

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