ArduinoISP on a serial-connected Board (Fio)?

I did burn the ArduinoISP sketch onto a Fio, which is connected via serial.
But if i want to use it as ISP to program another board (Gboard800), it does not work.
I set the programming output to verbose, so i see

         Using Port                    : usb
         Using Programmer              : arduinoisp
avrdude: Error: Could not find USBtiny device (0x2341/0x49)

i guess the output should be something like serial instead of usb?

In the ArduinoISP sketch, i saw some lines about using serial instead of USBvirtual.

/ On the Due and Zero, 'Serial' can be used too, provided you disable autoreset.
// To use 'Serial': #define SERIAL Serial

#ifdef SERIAL_PORT_USBVIRTUAL
#define SERIAL SERIAL_PORT_USBVIRTUAL
#else
#define SERIAL Serial
#endif
#define SERIAL Serial

As seen above, i copied the #define SERIAL Serial out of the if statement, but the comment also mentions i have to disable autoreset?
Did not find anything about that.

Generally, i am wandering in quite thick fog...
I am rusty on all this stuff.
Any hints?

What i try is to program this Gboard with what i have around, and the Fio is the only other 3V3 Board i have.
An AVRISP MKII Clone is on the way, but heck, it should be possible this way too, no?

sirtet:
avrdude: Error: Could not find USBtiny device (0x2341/0x49)

You need to select Tools > Programmer > Arduino as ISP.

sirtet:
As seen above, i copied the #define SERIAL Serial out of the if statement

Please revert all changes you made to the ArduinoISP sketch and upload an unmodified version of the sketch to your Fio. The sketch works just fine without any changes.

sirtet:
the comment also mentions i have to disable autoreset?
Did not find anything about that.

You should connect a 10 uF capacitor between the reset and ground pins on your Fio. That will disable autoreset. This is shown on the official Arduino as ISP tutorial, but for some reason they only shown it done on the Mega, and not the Uno. Sometimes you can get by without the capacitor but often not and it doesn't hurt anything to have it there.

sirtet:
it should be possible this way too, no?

The Arduino as ISP programmer has certainly has worked perfectly well for me a countless thousands of other people. In fact, I've had more problems with my AVRISP mkII (though I'll admit the automatic logic level selection feature is cool).

Does "disable autoreset" refer to the 10u cap. on the programmer? i do have that one in.

I noticed, under tools>programmer, there's also Arduino as ISP so i tried that.
(Brilliant idea, without knowing what it means...)
This gives me an output that says it uses the serial, but the errors are not talking to me...

        Using Port                    : COM4
         Using Programmer              : arduino
         Overriding Baud Rate          : 19200
avrdude: stk500_recv(): programmer is not responding
avrdude: stk500_getsync() attempt 1 of 10: not in sync: resp=0x6e
avrdude: stk500_getsync() attempt 2 of 10: not in sync: resp=0x66
avrdude: stk500_getsync() attempt 3 of 10: not in sync: resp=0x03
avrdude: stk500_getsync() attempt 4 of 10: not in sync: resp=0x66
avrdude: stk500_getsync() attempt 5 of 10: not in sync: resp=0x03
avrdude: stk500_getsync() attempt 6 of 10: not in sync: resp=0x66
avrdude: stk500_getsync() attempt 7 of 10: not in sync: resp=0x03
avrdude: stk500_getsync() attempt 8 of 10: not in sync: resp=0x66
avrdude: stk500_getsync() attempt 9 of 10: not in sync: resp=0x03
avrdude: stk500_getsync() attempt 10 of 10: not in sync: resp=0x66

sirtet:
Does "disable autoreset" refer to the 10u cap. on the programmer? i do have that one in.

Yes.

sirtet:
(Brilliant idea, without knowing what it means...)

Different ISP programmers work in different ways. For this reason, there is a definition of the parameters of each programmer type. In order for the Arduino IDE to know which definition to use, you need to select the correct programmer from the Tools > Programmer menu. To use your AVRISP mkII, you'll want to select Tools > Programmer > AVRISP mkII.

sirtet:
but the errors are not talking to me...

You need to do Sketch > Upload using programmer when you're uploading via an ISP programmer. You can't use the normal Upload button.

Thanks pert.

I did not see your first reply until after my 2nd post.
Now i reverted the changes to ArduinoISP, your other two hints were already in place.
But no luck, still same output as the last.

Yes, i did use upload via programmer. but initially i had ArduinoISP selected as programmer. That had worked before between two uno's.
It seems illogical to me to first flash ArduinoISP but then not use that as the Programmer...

I need to go sleep, but next i would look for issues with my serial connection, i use an FTDI Basic.
Not sure if the 3v3 on it is enough to power the FIO (Gboard has it's own power, 3v3 is not connected between the two).
Or if the DTR line is interferring...

sirtet:
It seems illogical to me to first flash ArduinoISP but then not use that as the Programmer...

It's extremely illogical. Naming the sketch ArduinoISP was a terrible decision that has caused much confusion over the years. They should have named it ArduinoAsISP. Tools > Programmer > ArduinoISP is for when you are using the ArduinoISP programmer that Arduino manufactures:

which is completely different from the Arduino as ISP and does not use the ArduinoISP sketch.