Programming xmega with usbasp & avrdude

Few days ago I got package from Helsinki Hacklab. Some generic component stuff and a couple Atmel xmegas and breakout boards for them.IMG_8517 Nice bit more powerful MCU’s than normal atmegas & attinys, but they eat only up to 3.3v, so better not to kill them with 5V logic. Luckily most 5v logics detect 3.3v as high, and their higher output can be lowered with resistor divider. Programing these xmegas also differ from their li’l brothers. Xmegas use  PDI, which is kind of two wire system, constant clock signal and data I/O. I did not have expensive atmel programmer, so I improvised cheap ~2€ programmer using usbasp and avrdude using these patches. Read More …

Unitrex 1200 and lesson

Yesterday I found an old calculator from e-waste center, which caught my attention. At first glance I knew that this was not ordinary VFD or LED display desktop calculator. So I stuffed it into my bag and scurried back to home with my precious find. At home I plugged the calculator into the wall socket, which I probably shouldn’t have done. Of course it did not work. But no worries, what could I could not fix? Read More …

Nixie clock firmware

Firmware for clock is in publishable condition at last. Now all major functions are implemented and no bugs are (yet) found. But there will be likely future versions with slight fixes and features. And yes, it is made with basic, terrible, horrible and not 1337 at all, but  it was easier and I could ask help from friend who have similarly constructed clock. There is also slight chance that I will translate this to avr gcc, but it would be big job, because it have not all functions and stuff. Read More …

Dual buck converter

I had boring day, and was too lazy to do school works, so what else I could do but electronics? For next project I need power supply and due to poor efficiency of linear regulators, I choose to make an another switching regulator.

IMG_7658And there is the blurry picture. Similar construction to the nixie clock’s power supply, but this time double. Read More …

Nixie-clock update

Itty Bitty Buck converter

Everybody knows old 78xx linear regulators. They are ok for many applications, but are problematic for bigger currents. They drop and regulate voltage smoothly for circuitry, but because all excess voltage are dissipate as heat, they are very inefficient. For my nixie clock I needed efficient little power supply for 5V rail, so I created this little baby:

Look how cute it is!

Read More …

SyncMaster 245b repair

A week ago I found Samsung SyncMaster 245b 24″ LCD monitor from trash. I tested it and it did barely power up. Blue led lighted in power button but nothing else. From the beginning I suspected powersupply, because its most common problem with LCD TVs and monitors. I opened display and started to examine the patient. Read More …

I feel so stupid ಠ_ಠ

Now I know why I2C was not working in my nixie clock. Today I got an arduino nano from helsinki hacklab, and started to troubleshoot my circuit. Oddly RTC worked when I tried it in breadboard, and also in clock’s motherboard, when nothing else were connected. Also noticed that when nixie driverboard was connected, both of the i2c lines had weird resistance to 5v and ground. I once again removed driver board from case and measured. It was ok, of course. I didn’t even tough about cabling <.< Read More …

Crimping connectors and waiting blue smoke

After a full day of work I have the electronics for the clock complete, or so I hope. And not a day without accidents; I spilled some Earl Grey to my Thinkpad T42’s keyboard, and now the m-letter is not working: I had to remap it to dead acute button. Now I need to get 300€ to buy thinkpad X60/x61(my X40 has a dead southbridge and writing with T42 without proper m-letter is very annoying). But back to the project.

Now I have the internals of the clock nearly finished. I fastened a mainboard to the bottom of the case because didn’t find the same L-mounts I used with the nixie control board. I also made a little board for the nixie psu. 

The mainboard is on the left. I originally wanted to install it the same way as control board but decided then screw it up to bottom of the case with spacers because this way it’s much more accessible. I positioned 170v psu to the bottom right corner with it’s own board in order to avoid shorts and interfere. Previously I somehow sorted 170v to 5v and burned all but russian K155ID1 IC’s. Soviet quality ;)

I am still waiting for a new atmega 16 (because the one in board seems to be broken too), and new usbasp programmer.