I am designing a PCB in which I am using the MCU used in Arduino UNO which is Atmega328P and some other components as per my project requirements. I have almost designed the circuit but I am confused with the USB programming part. I want my MCU to be programmed using USB B Type just like we do it in Arduino UNO. My friend suggests me to purchase an Arduino UNO device and program that MCU and then put it in my circuit. But I don't want to do it like this. I have found the schematic design but its very confusing. Can anyone help me out with this.?

  • Eh. Save yourself the pain and just use ISP. Sep 28, 2015 at 6:51
  • Can you explain more.?
    – Aircraft
    Sep 28, 2015 at 6:56
  • You can use an Arduino to program a bootloader into an ATmega328. There's even an official tutorial for that.
    – Nick Alexeev
    Sep 28, 2015 at 6:57
  • I fail to see why you think this is so confusing. If you want the functionality of an Arduino UNO then just duplicate the schematic into your project. Fully. You will end up with two MCUs in your project just like the UNO. BTW these MCUs are quite inexpensive.
    – Michael Karas
    Sep 28, 2015 at 8:51
  • The "core" part of the arduino uno board is the Atmega328P, with the 16MHz oscillator (can be removed if you want to use the internal 8MHz clock - search for optiboot) bypass capacitor(s) (C6, but I suggest you to put another one close to the other pair of power pins), reset circuit (RN1D and, I suggest you, also the button), ICSP connector and, suggested, capacitor C4. You will need an ISP programmer to put at least the bootloader on board. If you want to program through serial, just add a usb-serial converter (suggested: FTDI). If it has also the DTR pin, you can enable auto-reset
    – frarugi87
    Mar 15, 2016 at 12:21

3 Answers 3


It is quite a lot simpler to obtain an FTDI USB - TTL Serial cable. (The link goes to the American supplier, Sparkfun, but such cables are available from many online suppliers.) They are typically made with a 6-pin female header instead of a USB B connector; you may have to make up that part yourself, if it is important to you. If you only need USB functionality for programming, one cable can serve any number of boards (one at a time, of course), no need to build it into each board.

  • 1
    Not 100% exact. In fact this requires you to have a Atmega328P with bootloader; commonly sold atmega, however, do not have it, so you will also need the ICSP port to program the bootloader the first time
    – frarugi87
    Mar 15, 2016 at 12:16
  • It takes only one chip with a bootloader to make an arduino work-alike which can then flash the bootloader into bare chips. A borrowed work-alike can flash that first chip. The OP seems familiar with Arduino and there was no constraint that no Arduino should ever be used
    – JRobert
    Mar 15, 2016 at 23:02
  • Totally agree, but... If there is no ICSP connector on the PCB then you will not be able to program it once soldered. Hence, the "not 100% exact", since you can fix it by pre-programming the bootloader, but 1) it's more useful to put an ICSP connector on the PCB (if the bootloader gets corrupted you can flash it again later), and 2) better saying it before the OP solders the IC on the board (and then finds out he can't upload with just a USB-TTL cable)
    – frarugi87
    Mar 15, 2016 at 23:42

Looking at the schematic design, you need atmega8 to make a usb programming connection. Design your circuit exactly like in the schematic.You will also need bootloader for it, so use any programmer like usbasp, connect its pins to mosi, miso sck, rst,vcc,gnd and click on burn boot loader in arduino ide


If you wanted a more permanent option on the board, you could also add a USB to FTDI chip like this: http://www.mouser.com/Search/m_ProductDetail.aspx?FTDI%2fFT232RL-REEL%2f&qs=D1%2fPMqvA103RC6OU6bKtoA%3d%3d&gclid=CNmDjr7dvssCFYZefgod9jgPeQ

  • 1
    Again, this requires you to already have a Atmega328P with bootloader
    – frarugi87
    Mar 15, 2016 at 12:16

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