USBTinyISP and arduino pro mini 3.3V

[dakky]

Hello ;)

i'm quite new to this whole AVR programming stuff and a little bit confused.
what do i want to do?

1. setting fuses on the mini
2. of course, uploading sketches to the mini

what do i have access to?

1. arduino uno (will become mqtt gateway)
2. an arduino pro mini 3.3V (as soon as thex become delivered :stuck_out_tongue_closed_eyes: )
3. an usbtinyisp (this model)
4. a ftdi basic breakout board

so whats the problem?
As @tbowmo mentioned HERE, the tfdi board cant be used to set the fuses (why btw? it offers all 6 connections to wire the pro up doesn't it?) for "underclocking" the pro.

So i hope i can use the usbtinyisp. BUT this device always delivers 5V, which would kill the pro? even when pulling the jumper off, i can see 5V :anguished: ? what might be wrong there?
Oh and i found a lot of documentation here, but this usbtiny looks completely different from mine :expressionless: There is also mentioned, that, when pulling off the jumper, the usbtiny only deliveres the voltage needed by the target (which is what i could need), but again, i'm not sure, if that also counts for my usbtiny.

So if i can't get the usbtiny to work with the pro i could use the uno to set the fuses and program the pro? (which I would like to avoid, because it's my gateway ;) ) I found this tutorial, but it says explicitly only for 5V arduino pros :disappointed:

could u please explain to me, how to handle this?

greetings
Dakky

[tbowmo]

@dakky

I have no experience with usbtinyISP (have a jtagice3 from atmel). That said, to answer some of your questions:

FTDI is a usb to serial port device, and you can not set fuses through the serial port on the atmel, this can only be done through the ISP interface (or jtag, debugwire etc.) this is because fuses can not be set by code running on the CPU itself. And by using FTDI you are communicating with a bootloader that is running on the cpu. While the ISP port is programming the flash directly, without bootloader.

It should not harm a 3v3 arduino, to be powered by 5V when programming. (The atmega328p supported supply range is 1.8 -> 5.5V, if I remember correct)

If it was me, I would remove the jumper on the usbTinyISP, and try to program the device.

[dakky]

this will work i think, but not sure what will happen, after removing the regulator from the pro (http://iot-playground.com/2-uncategorised/9-arduino-low-power-sensor).
I hate it, that i don't find any useful documentation about my usbtiny grml :disappointed: