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gcc unwanted loop hoisting?
Compiling with -Os, avr-gcc 5.4.0 seems to be making unwanted speed optimizations at the cost of space.  Here's some sample code and the resulting asm: void sput(char* s...
Saturday, 14 March 2020 - 22:28
more avr-g++ stupid optimizations (integer promotion?)
avr-gcc 5.4.0 (also tested 4.9.2), -Os -flto, compiled as C uint8_t printHex(uint8_t value) { dbgtx(nibbletohex(value>>4)); 68: 28 2f mov r18, r24...
Sunday, 1 March 2020 - 15:31
spike filter details?
Does anyone have details (hopefully a schematic) of the reset spike filter?  I've been testing ADC0 on 8-pin tinies like the t13 and t85, without disabling reset.  I'm...
Thursday, 20 February 2020 - 23:00
unconnected pins usually don't float
Over the years I've read lots of comments about floating input pins.  I've usually found that unconnected pins read as zero, but never did any thorough testing.  A few...
Sunday, 16 February 2020 - 22:42
Building a better bit-bang UART
I've written a blog post describing asynchronous serial UART communication and my bit-bang UART library, picoUART. http://nerdralph.blogspot.com/20...  
Thursday, 13 February 2020 - 02:08
integer promotion difference between gnu11 and gnu++11
I read a few of the previous discussions on integer promotion, and none of them mentioned differences between avr-gcc (5.4.0) in gnu11 and gnu++11 modes (the default for avr-gcc...
Sunday, 9 February 2020 - 21:20
avr-gcc inline assembler concrete documentation?
Is anyone aware of a very good, technical description of avr-gcc inline asm?  It took me only a few months to learn straight asm (i.e. write main.S, compile with avr-gcc),...
Wednesday, 29 January 2020 - 17:24
logic diagram for HV programming mode?
I want to make some improvements to my HVSP fuse resetter, and am trying to figure out the logic of how the modern (with enhanced POR) tinies enter HV programming mode. ...
Saturday, 18 January 2020 - 18:51
picoboot v3 beta release
256 bytes of assembler, Arduino bootloader compatible (avrdude -c arduino), with autobaud (minimum 19,200bps @ 16Mhz).  At 500kbps, it will read 32kB of flash on the m328 in...
Sunday, 12 January 2020 - 01:30
updated USBasp firmware
I'm updating and improving the original USBasp code.  The latest code on Thomas Fischl's site is 2011-05-28, without any updates in 3.5 years.   This code (...
Sunday, 23 November 2014 - 00:07
new scope - Rigol DS1054Z
After more than 30 years since I started tinkering with electronics, I'm buying my first scope - the Rigol DS1054Z.  It's on back-order everywhere I checked, but if all goes...
Thursday, 20 November 2014 - 19:33
Oshpark minimum dimension = .25"
I'm making a small breakout board, and my first version was only 230 mils wide.  I didn't realize that OshPark has a 250 mil minimum dimension, so I had to make it a tiny bit...
Sunday, 2 November 2014 - 17:53

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