Sun, 09 Jan 2011
I finished my Ph.D. thesis about electrostatic micromechanical devices in April 2010 (Buy). Originally I wanted to print a small flip-book in the header or footer visualizing my work, but discarded the plan after seeing some eyebrow raising of my proof readers.
I still had the idea in mind though and after some tinkering around implemented an animation with Povray.
To get a paper flip-book from that, the images have to be distributed over a piece of paper. As I don't like office applications very much, I ended up writing a small Python script which creates a PDF employing the excellent pypdf package. The result just lacks some cutting lines.
All necessary files are in this git repository.
Wed, 17 Nov 2010
Error code: ssl_error_rx_record_too_longor Chrome / Chromium / Webkit complaining with
Error 107 (net::ERR_SSL_PROTOCOL_ERROR): SSL protocol error.and you just reconfigured your Apache webserver, adding a new VirtualHost on port 443, make sure you didn't forget
SSLEnable onin the VirtualHost block. Otherwise Apache tries to serve non-encrypted content over the SSL-port and web browsers don't like that and don't produce helpful error messages. Nothing in the Apache log files either...
Fri, 12 Nov 2010
It just took me the better part of a day to find out why my o-so-simple microcontroller couldn't be programmed. I've this really simple board, consisting basically of a ATmega8 or ATmega8l, a 6-pin standard ISP connector and some surrounding power supply parts (no external clock).
Now, if you take a ATmega8 from the reel it comes pre-programmed to run with 1 MHz from the internal oscillator. Trying to access and program the device connected to an STK500 SDK using avrdude always resulted in errors:
avrdude: Device signature = 0x010305or
avrdude: Device signature = 0x010307Strange. Because normally you can either program the device or it doesn't respond at all (0x010301 and 0x010304 also turned up sometimes, in AVR studio speak: 0x01 0x03 [0x05,0x04,0x01].
I double checked all solder connections and even tried three (!) different devices on different PCBs, even from different production lots. Always the same error.
Meanwhile I had already checked the STK500 against other development boards equipped with an ATmega168 and ATmega8 - those worked.
Finally I dug out an old Windows XP machine running the AVRstudio, and there it occurred to me:
To speed up programming, I had increased the ISP frequency from default 115.2 kHz to 460.8 kHz. Turns out that the fine print says, that the ISP frequency should be lower than 1/4 of the microcontroller clock (1 MHz in this case). 1 MHz / 4 = 250 kHz - so I was well above. Turning the frequency down to 115.2 kHz made everything magically work.
avrdude: Device signature = 0x1e9307 avrdude: safemode: Fuses OK avrdude done. Thank you.
I hope to save someone else some time with this post