JTAG muxed ADC channels on AVR?

Yes, for sure. Or use external MUX off ADC0-3.

Yes, you have to disable JTAG via fuses. That's typical problem with AVR JTAG pins.

Vladimir Vassilevsky DSP and Mixed Signal Design Consultant

Bugger. That answer is concise, accurate, and a complete pain in my rump.

Thanks.

hmmm, an idea. Have to decide if that is less trouble than reworking it. (It's a prototype only and it needs to be rebuilt from scratch anyway, but we were hoping to do a little more testing with the existing hardware before the next phase).

You can switch to ISP over SPI.

Looks like your code is fairly complete, so you may not really need full JTAG debugging.

That's exactly what I'm going to do. It just makes everything a bit irksome because I can't see what the actual ADC values are. Oh, and having to find my AVR-ISP :)

Hmm... reminds me of that joke about an answer that must have been given by a mathematician because it's so wonderfully short, extremely correct, .... and completely useless.

n=20

,=20

Reminds me of that joke about an answer that must have been given by a=20 manager: somebody else's design problem from now on must become my=20 personal problem.

VLV

You can disable the JTAG interface under program control even if the fuses have it enabled. So depending on your application it may be appropriate to have JTAG disabled when needed by the program and enabled when you need it for programming/debugging.

kevin

Hmm, I'm not short, when correct extremely so, and completely useless (according to the wife)... and of course a mathematician by training. I take offense that mathematical answers can be the butt of jokes. Many modern theorems are extremely long. The are correct or not, so 'extremely' is superfluous. Further, the answer can't be useless if it is an answer to the question unless the question itself was set up that way.

:-) Peter

I didn't know that! Thanks for the info.

You can disable the JTAG pins in software. Obviously you cannot then debug via JTAG from that point, but it means you can still use the JTAG pins fro programming the device.

Try this snippet I got off the web.

void disable_JTAG(void) { unsigned char sreg;

sreg = SREG; cli(); MCUCR |= ( 1

Yes, for the first time. If you have the software running with jtag disabled, you still have to erase/reprogram it with SPI.

yep the 4 cycles is important, remember doing multiple variations of code and compiler setting before I gave up and wrote it in asm to make it work

-Lasse

Obviously, you can use the pin change interrupt on another pin to enable/disable the JTAG as needed. If the pin is also enables a buffer, you don't have to remove the JTAGICE Mk II.