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I have a FT232R that I want to use to flash my ATTiny85 bootloader in the Arduino IDE, can someone help me out on this? I don't want to get a AVR programmer.

  • This is certainly possible but it's very inconvenient and not commonly done. It's much better to buy a cheap 6 pin USBasp clone off eBay or use another Arduino board as an "Arduino as ISP" programmer. It's possible because the FT232 has a bit bang mode but it's very slow. You can find instructions here: learn.adafruit.com/ftdi-friend/…, you just need to adapt the instructions to the ATtiny85 (SPI connections and board selection). I've never done this so I'm not going to write an answer but if you are successful please answer your own question. – per1234 Aug 8 '17 at 3:33
  • It's also not very common to use a bootloader on the ATtiny85 due to the limited flash memory. Usually you will upload sketches to the ATtiny85 using an ISP programmer. For that usage the FT232 is even more inconvenient because it's so slow and you will typically upload more often than you would burn a bootloader. – per1234 Aug 8 '17 at 3:35
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A bootloader is a program that gets loaded into the bare microcontroller to handle a number of low level tasks. One of those tasks is the ability to load a program over UART (serial).

As such, the bootloader can be loaded into the microcontroller using a AVR programmer. Once this has occurred, you can then easily load in programs with the FT232R.

It is possible to use the bitbang mode on the FT232R to load the bootloader into an Arduino board, hence replacing the AVR programmer. So, it can work but it isn't easy.

As suggested by per1234, there is some instructions on how to do this to an Arduino Diecimila on the Adafruit website: Programming the Arduino Bootloader In general the full page has a lot of useful information: Full page

  • Sorry for a late reply!, but can't you run the FT232R in bitbang mode? – Pepperrika Aug 17 '17 at 21:20
  • @sa_leinad ... "I am sorry to say that what you are trying won't work." ... no, you can bitbang the FTDI and mimic an ISP programmer that way. – gone Sep 7 '17 at 2:11
  • @yeti & Pepperrika, You are both correct. However this requires a certain level of expertise. Beginners especially won't be able to do this. However, if a beginner had a ISP then a beginner could easily program the bootloader into the ATTiny85 using the Arduino IDE. – sa_leinad Sep 7 '17 at 6:07
  • So you agree that "... that ... won't work." is a false statement. And we all had missing expertise on nearly all topics somewhen in the past. Well... wiring up a FTDI module probably is not more difficult than wiring up an ISP... and avrdude supports them, so it will not be rocket science. I agree that having an ISP is the easiest way to go but @Pepperrika asked about it being doable with a FTDI and to this the answer only can be: YES! – gone Sep 7 '17 at 13:44
  • @yeti, why don't you post your own answer if you have such a problem with mine. I've edited my answer - upvote it if you think it is now worthy. – sa_leinad Sep 7 '17 at 17:02

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