Anone know how I can output text to a terminal window via ICSP?

I stupidly designed my boards not to have an FTDI connection and now I'm paying for it now that it's time to debug them. I've read there's a way to get debug data over ISP but the one site I can find mentioning it Firefox is warning me may be a potential attack site, and I can't afford to have my PC screwed up right at this moment. I found the alleged source elsewhere in the form of something called "little wire" but it requires a terminal that's not compiled, and I don't know how to compile stuff with MinGW and I don't have time to spend four hours figuring the whole thing out only to find out it doesn't work. I really need something working right now because I have some people waiting on these boards for Halloween and I've got two days at most left to get them up and running.

I've been hobbling along so far blinking an LED on my board but I really need that debug window. Has anyone got something like this set up?

I did have the forethought to break out every single pin I could on the board by the way. So while I do not have access to RX0 and TX0 because they are used by the SD card I am trying to debug, I do have access to RX1 TX1 and SCK1, plus almost all the other pins besides the stuff for the SPI available.

Might there be some way to use FTDI over these other RX/TX pins?

TinyISP may help...

It also may help with the slow uploads. I hope to have time tonight to investigate.

See here about SPI / I2C debugging:

Might there be some way to use FTDI over these other RX/TX pins?

You could use SoftwareSerial, but if possible the SPI (or I2C) debugging will be faster.

I think I may have found an ideal solution. Someone seems to have made a version of Optiboot specifcically for the 1284P which can upload via USART1:

More info:

Specifically, about how to output the serial data: use serial1() instead of serial()

Got the FTDI up and running. It ended up being surprisingly elegant. Two wires for power, two for RX and TX to the USART1 port I broke out, and a momentary pushbutton attached to the ISP port for reset. Now I can stop debugging by blinking an LED. Dear god that sucked.