Update Readme #264
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Update Readme #264
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The logic high of most LEDs parts is VCC * 0.7. When powered at 5V that means logic HIGH is defined as 3.6V (up to 5.5V according to: https://cdn-shop.adafruit.com/datasheets/WS2812B.pdf) and 3.3V is technically in the undefined band between LOW and HIGH. But my experience matches yours; I've driven several different styles of WS2812-compatible LED directly from 3.3V while powered at 5V and they appear to work fine. I would probably change the text slightly to:
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brindosch
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Apr 5, 2018
* Added delay to ensure reset time being met with low led counts (jgarff#157) * Fix includes as per jgarff#178 (jgarff#189) * clean up doco and strandtest (jgarff#187) * updated documentation on GPIO usage strandtest now defaults to GRB colour order added version.h to gitignore * updated python readme * more README cleanup * added notes on spi max transfer size * Fix freeze after running for long time (jgarff#197) * Whitespace cleanup * Move channel_protocol_time so it handles 32 bit Color LEDs. * Fix a freezing issue when running for a long time. When current_timestamp overflowed 2^64, rolling back to 0 and ws2811->render_wait_until had not, this caused an incredibly long usleep in ws2811_render. * Update README.md (jgarff#191) * Update README.md * updated spi buffer size location * Add -lrt link flag for systems with older glibc (jgarff#195) * Fix 32-bit overflow in get_microsecond_timestamp(). (jgarff#206) On Raspbian systems, the tv_sec member of struct timespec is 32 bits wide. get_microsecond_timestamp() was overflowing in 32-bit arithmetic on this member. This causes the time that it returns to jump ahead by many thousands of years at uptime = 35 minutes, 48 seconds. (While the starting point for CLOCK_MONOTONIC_RAW is unspecified, it seems to track system uptime in practice.) This overflow didn't cause noticeable problems for me--ws2811_render() skips the sleep when it thinks such a huge amount time has elapsed--but it could possibly result in rarely-occurring skipped frames if the WS2811 reset time isn't effectively honored by ws2811_render(). * Add TOOLCHAIN option for cross compilation (jgarff#213) Use this option if you want to cross-compile the library. Typical usage is: scons TOOLCHAIN=arm-linux-gnueabihf * Add -Wextra compile option and adapt code to suppress warnings (jgarff#214) The changes in code are mostly type casts between int ann unsigned. * Add shared library rasbpian package builder. The package is not built by default. To generate the package you need: - The dpkg-deb utility. - Use "scons deb" to generate the package. * Merge user-settable gamma correction into master (jgarff#216) Merge user-settable gamma correction into master * Bug fixes for Stretch and Compute Module support (jgarff#222) * Bug fixes Missing aligned(4) attribute in pcm.h makes the PCM case failing under Stretch, due to a newer version of gcc (6.x). Also fixed a bug in check_hwver_and_gpionum, so original Model A is recognised. * README, using SPI on RPi3 Added note to change the core frequency to 250 MHz when using SPI on RPi 3. * README fix * Add support for Compute Module 1 and 3 * Fix undefined clock_gettime symbol * add missing memory allocation for SPI mode (jgarff#231) * added Ctrl-C handler to turn off all LEDs on exit (jgarff#140) * added Ctrl-C handler to turn off all LEDs on exit * added option -c * Fix for segmentation fault on exit for Python API (jgarff#239) Remove useless __del__ because the cleanup() function gets called by atexit(). Remove ws.ws2811_fini() call which causes the SEGFAULT on exit. Python does not complain about the memory leak in this way. * Add support for new A+ hardware. * Change default DMA channel to safe choice (10) (jgarff#253) add warning on README.md * Add getBrightness for brightness feedback from the buffer (jgarff#248) * Instructions to install the Python library (jgarff#254) Solving issue jgarff#142 * Fix for non-root users & SPI (jgarff#257) * Fix for non-root users can use SPI * use DEFINE'd device strings also add a note to the readme * Basic Golang Examples (jgarff#256) * Added golang example * Added basic README for golang examples. Added os exits for errors during color wipes for golang examples * Fix the default DMA in python code (jgarff#266) DMA 5 causes file system errors on PI 3 * Fixed typo in README.md (jgarff#273) Was perusing recent commits and saw this. * clarify electrical notes (jgarff#264) * Fixed strandtest.py (jgarff#258) * Fixed keyboardinterrupt, indentation inconsistency, & a few other minor bugs. Added shebang. * Fixed KeyboardInterrupt. Again. * KeyboardInterrupt works now. For sure. * Tabs to spaces, removed redundant signal handling * Removed unused sys module import * Added Raspberry Pi 3 B+ (jgarff#276) * Added Pi 3 B+ * Remove unused import
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The hi-level of the 3.3V output of the RPi is sometimes sufficient to be recognized as high by the LEDs. I changed the readme slightly to reflect this. (source: I have one of my SK6812 strips connected directly)