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Digilent Electronics Explorer AVR Protocol


ebattaglia42

Question

Hi,

I've been experimenting with the AVR protocol in waveforms on the electronics explorer, and I've been getting some weird results. For most speeds the board is not identified correctly, and for the speeds that do work, verification always fails after writing flash. The connection is sometimes stable enough to read/write fuses. I've tested with a few boards (2 attiny85, 2 atmega328p). All of them program fine with other ISP options.

I imagine I'm just doing something wrong, so could anyone point me in the direction of some resources? My simplest test case is just an ATtiny85 connected to 5v or 3.3v with the ISP wires connected directly. The internal clock is 16MHz and I checked it's calibration. 

Thanks!

 

 

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Hi @ebattaglia42

I've added this AVR interface because I had to program ATmega328PB and ATtiny44A, and I thought it may be useful for other people too. 
Try using lower frequency like 1/10kHz. The auto-rate simply looks for the highest frequency it can enter programming mode.
The IOs on EE and AD are 0/3.3V logic. Having higher voltages on the external device, the IO protection circuit may drain high current from the device.

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Hi @attila,

Thanks for the response. I think its a great addition.

I'm currently powering the attiny85 with 3.3v, so the logic should work out. I actually get less reliability at lower clock rates. It only enters programming mode above 500kHz, and even then only works 10% of the time. At 2MHz it enters around 90% of the time, but verifications still fail.

I'm pretty sure the chips are good, because they verify fine on other programmers at 3.3V. 

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@attila As an update, I was playing around with it again today and somehow burnt out the attiny85 and the atmega328p. They were powered at 3.3V, were somewhat readable, and then suddenly stopped entering programming mode. I was unable to recover them with other ISPs. Do you know why they could have burnt out? In both cases, an unsuccessful write was performed first. I did not touch the fuses, at least intentionally.

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