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AVR High voltage programming (Fuses rescue)
Nixie PC Meter/Monitor
Ugh no no. It's not a transistor. It must be a 7805 :/ Thats what happens... with a board in hands... without the schematics... plus not feature in the reference link. Anyway... solved!
Alright. From reference link http://denki.world3.net/avr_rescue.html and board layout I conclude: The first transistor is a PNP, it's collector goes to atmega pin 7 (VCC). It's useless ad it's base is always grounded. It will be probably hot (and die occasionally), because there aren't any transistor driving its base. I will just change this PNP to a wire jumper pin7->VCC like in the reference link. Anyway, thanks for the layout! Going to try resurrecting some atmegas in some minutes.
Hello. I just etched the board. i use DipTrace and cant open the schematics. Was trying to solder parts anyway but: At first glance the first transistor looks like a PNP BJT; It's really a BJT PNP? If so... it's base is directly connected to power ground (so always saturated anyway?), and if it's a BJT: No resistor between base and ground, thats really very bad. So well maybe it's not a BJT, what part is that? I can see just a 2N3904 in the reference link http://denki.world3.net/avr_rescue.html . Thanks!
There we go
Hi, sorry for the late response. The build looks very nice and I'm glad you got it working. I don't remember what BC I used, it probably had a different pin orientation. As for the code part, I did not change it a bit, I'm not that skilled in programming :) My understanding is that the fuses are reset to a factory default after which you can set them up as you want. What I forgot to mention, and I think I got this way after I built this, is that it is highly dependent on the crystal. In other words, since this schematic does not use a crystal, when you reset an MCU then you reset also the crystal settings; if you place it immediately in a programmer (with a crystal) and don't take this into consideration then you may end up with some errors. I will probably design and build another version - SMD based (1206 most probably).PS: thanks for building it :)
one more thing, i am using a Atmega 328 as IC1 (the programmer) I compiled the c file in atmel studio to accomodate the 328 and uploaded the new hex file with an atmel ice programmer :-)
Ok i got it working, and it's really great. I am resurrecting both Atmega328 and 328P processors, it takes like 2 seconds :-) Great!Of course the emitter has to be tied to ground, it still looks like wrong orientation in your picture but maybe the picture is fooling me? BTW i am using a BC337 transistor which is almost the same as a 338. I guess it's just acting as a switch on the IC2 reset so about any bjt transistor should work.I did the PCB on a milling machine and had to do my own modification to the board layout, it's quite impossible to solder ic socket on the top with a ground plane just 8mils from the pad :-D I changed the fuse settings to match the default in Atmega 328P, the new values is:HFUSE0xD9LFUSE0x62I found the values from the link in the code:http://www.engbedded.com/cgi-bin/fc.cgiGood simple project! Thank you.
Hi there. I did a build of this and am using the atmega 328. If i look at your picture it looks like the BC338 is upside down compared to the schematic?? Should the collector be connected to Vin or should the Emitter?
it works with atmega8? Thank you
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