AVRISP-II and AVRDUDE

[MikeB]

I use an AVRISP-II programmer for flashing Atmel AVR processors, but I couldn't use it with eepe as Atmel Studio 6.0 loads its own drivers that don't work with AVRDUDE.

I just found this site however:
http://www.visualmicro.com/post/2014/01 ... duino.aspx

and, having followed the instructions, I now have the AVRISP-II working with AVRDUDE and eepe.

There is one other problem with using the AVRISP-II, the same problem I have with my STK500. The signal drivers cannot cope with the capacitors that load the reset and signal lines. I solved this for the STK500 by buffering the programmer output signals with some 74AC devices. These provide plenty of drive and I use this with both the STK500 and the AVRISP-II.

Mike.

[Escrich]

Hi Mike, which IC have you used as buffer?
As we discussed latest days I have this same problem, and simply I whan't to know if you used buffers, or nor or nand gates, just to go directly and not to waste time.
Thanks for all of your help

[MikeB]

I believe I used a 74AC04 device, with the gates used in pairs to provide a non-inverting buffer on each of RESET, SCK and MOSI.

Mike

[Escrich]

Then i can understand that MISO is a bidirectional signal, am i right?

[MikeB]

No, MISO is data from the AVR processor to the programmer (Master In Slave Out).

Mike

[Escrich]

Here you, and whoever have something that could help.

Buffer PCB.rar

Circuit and pcb design for buffer

(58.24 KiB) Downloaded 11 times

Thanks a lot for your help

[jhsa]

I believe I used a 74AC04 device, with the gates used in pairs to provide a non-inverting buffer on each of RESET, SCK and MOSI.

Mike

Mike, wouldn't a CD4069 do the job? I think it might be easier to find and probably cheaper?

João

[MikeB]

Unlikely! The point of this buffering is to use a high current output drive, the '4069 only drives 1mA at 5V, the 74AC devices drive 24mA.

Mike

[jhsa]

Understood. Thanks for the explanation..

João