Attiny3217 Serial monitoring without another atmel processor?

Hello i have seen other projects using the attiny3217 processor on serial monitoring using another atmel processor like the 328p or something else to interface between them. Is it possible to use a ftdi or usb to serial chip to do the same thing? I'm sorry still new to the attiny processorings to figure this all out.

edit: There is a RX and TX pins that why I'm asking if this is possible?


It's not clear what you mean by "serial monitoring". Maybe you could post a link to the project you mention.

Well, I don't know what is this "same thing" you are interested in doing, but, any USB to TTL serial adapter chip will allow you to communicate between your computer and the ATtiny3217 via its UART.

Hello Pert. Sorry If I'm not clear my fault. What I'm trying to say is I have been seeing arduino uno boards programming the attiny3217 processor and having serial monitoring on it. But i also notice that The 3217 processor has a RX and TX connection on it. I was wondering if I use a programmer like the Ch340 or ftdi on it would i be able to still program it and have Serial monitoring on it.

Edit: This might be really a programming question then a microcontroller question.


Can you provide a link, please; it might make it easier for us to understand.

If you refer to the Programing Questions section on this forum, that's for problems with the language, not for uploading code :wink:

You can also look here for using a USBTTL adapter for programming these tinyAVR devices over UPDI: AVR-Guidance/ at master · SpenceKonde/AVR-Guidance · GitHub

Hello Sterretje, I don't have a link to using a attiny3217 with a ftdi or ch340. That is what My question is all about. Is it possible to do that with a ftdi or a ch340 instead of using a uno bnoard in udpi mode? But it looks like this is really a programming question i have placed in the wrong place.


That's not what I asked :wink: A link to an article where people use an Arduino Uno board to program the attiny3217.

Link 1
Link 2

Here they are.

Edit: Sorry link 1 is the breakout board he designed and made the second link is the programming.


Optiboot has been re-written to work on the tiny-0 and tiny-1 chips, and SpenceKonde's megaTinyCore supports the chip both with and without optiboot.
Once you have loaded optiboot onto an ATtiny3217 (which requires a UPDI programmer; similar but slightly different than needing an ISP programmer to put the bootloader on an ATmega328p chip), you can upload and do application-level Serial communications over the same UART port, just like an Uno or nano.

PROBABLY you need to set up a way to power-cycle the chip, because it doesn't have a "reset" pin by default.

I THINK the source of confusion here is that UPDI programming also uses a UART (with a bit of special wiring); so to burn the bootloader onto a UPDI chip, you connect up some RX/TX thing to the UPDI pin, but after the bootloader has been burnt, you'd connect to the RX/TX pin of the 3217 instead of the UPDI pin.

I don't know of any existing boards for sale, or theoretical designs, that implement an ATtiny3217 + USB/Serial chip to yield an Uno-like board. For one thing, even though the t3217 is theoretically cheaper than an ATmega328p, it would be nearly impossible to produce something that competed with the price point of the Chinese Nano derivatives (or even the official Arduino Nano Every.)

hello Westfw. Thank you for expalining to me better. So The UPDI really for programming it then i should be able to use a uart like a ftdi or ch340 to do some serial monitoring or even upload new sketches if need to in thoery.

Edit: Or am i wrong? Sorry if i miss understood this wetfw.


I'm also curious to see what will happen here and also to see if the boot loader will still be as important for the UPDI programmable devices since it can now be much easier to do everything with a USBTTL device. Everything meaning programming it and viewing the serial console. I did put a small "proof of concept" together, based on an ATtiny1614: ATtiny1614 / USBTTL adapter for UPDI programming and serial console access. It still has one manual step to be eliminated, but I've been hanging around to see what @DrAzzy comes up with here because he has been talking about this too.

I followed DrAzzy once my self. That is what gave me the idea on the 3217 chip. I'm wondering if uploading new sketches and serial monitoring by the Rx and TX is possible after uploading the bootloading Via the UPDI?

This is what got me really Curious.


A TTL / USB cable may simplify things.
here is a 5V one USB to TTL Serial Cable (5V VCC) - CAB-17831 - SparkFun Electronics
There are 3V3 ones as well.

The question wasn't about getting cables or usb to serial chips. The question is can i program the attiny3217 processor with a new sketch and serial monitoring with a ch340 or a ftdi after uploading the bootloader using a updi programming.


I think that a USB-serial integrated board would only be interesting once the 3226 and 3227 are available, because they have the alt-reset that would make using a bootloader not absolutely suck. I';m gonna place an order with the board house shortly for some revised versions of my AVR128DB32-with-serial-adapter-on-board (I'm calling it Azduino Nano - though it's similar in size, it doesn't share the pinout of the Arduino Nano, because that pinout is godawful, and suffers from the same malady as most boards of forcing the use of breadboard or some sort of splitter by virtue of having hardly any power and ground pins.) It gets 23 usable I/O pins 4 of which are MVIO capable. You'll set the MVIO voltage via solder bridge to either 5v, 3.3v or PD2; the last being the output of the on-chip opamp, so you can do what Microchip describes in their app notes about using the opamp as voltage follower for the DAC to generate a (low current) supply for VDDIO2...

I hadn't been planning on anything for the Tinies though. Should I be?

I could imagine that the reset button would be a refined implementation of a crude push to break button on the Vcc pin of those chips which don’t support the additional reset pin. Simply to force a power fail restart.

I don’t know the answer to this. What I can say is that people will be developing with them and anything which makes the entire development workflow easier should be welcomed. That does not , of course , mean necessarily that they will also be prepared to spend big $$s on products offering such convenience.

The AVR128DB32 stuff sounds interesting.

Reset button? Who said anything about a reset button? (most of my boards don't have one - though I have started putting them on the full size Dx-series breakout boards) The bigger problem is autoreset for the bootloader...

And I'm sorry, but I'm not going to make a board with an NC switch in series with power.

OK. I'll probably leave this for another time and another thread since it is going beyond the ideas which the OP raised.

I see that I didn't make it clear. I was actually talking about scenario where a bootloader was NOT used on one of these TinyAVR series 1 chips, leading to the unavailability of the reset pin since the UPDI pin would still then be required for uploading user sketches. Hence, then , the further point about the reset button which I would find convenient to have.

Or put even more explicitly, with UPDI, what is the current justification for using a bootloader ? Clearly, in the past , when a separate programmer was necessary, a bootloader was quite convenient and saved a lot of fiddling about. Now everything can be done with the same USBTTL device.

Hello Everyone. Thank you all for the Information.

6v6gt you are right the Reset and the updi are the same pin which needs to be addressed. That is one of my problems after uploading.

DrAzzy I think you are doing some great things with the Tinnycore project. I have larned a lot with theses processors from you. Dr Azzy Point of Programming Via UPDI and Serial Monitoring through the RX and Tx pins is a great idea.

I message him and he told me to program it that way. Because if i program if all Via through Serial then the UPDI Then i lose the UPDI when I need to rebootload it and I will need a higher voltage on the Reset pin. I found out it is a 12v i need to do that. Which it not a big deal. I deal with high voltage daily.

But over all thank you all for the help and support this community is awesome. I have all my question on this topic answered.


I don’t think it’s easy/cheap to use the same usb/serial device to connect to both updi AND a uart.

You quickly (?) end up with a “nano every” like design with a samd11 or something to implement two ports…. (Hmm. Wonder how a samd11 would work if it implemented two serial ports instead of one serial and one jtagupd, and then used the host-side sw for doing updi over serial…)