it seems like i have screen burn in and for some reason it's visible ONLY on dark grey background

<p><span class="h-card" translate="no"><a href="https://mastodon.social/@whitequark" class="u-url mention">@<span>whitequark</span></a></span> The Adafruit HD44870 I2C backpack has this weird issue where it won&#39;t reliably print the correct characters unless I solder the unused pins on the port expander to ground.</p><p>Confirmed across multiple backpacks.</p>

<p><span class="h-card" translate="no"><a href="https://mastodon.social/@whitequark" class="u-url mention">@<span>whitequark</span></a></span> Nice to hear that! I already suspected that these would be useful for Glasgow / Amaranth development.</p>

<p>Okay, this fucking rocks. Good job Steam team.</p>

<p>so if you&#39;re having issues that make No Sense and disappear if you place your finger near the chip or connect a scope, try twisting a ground wire (you have eight!) with either the likely aggressor signal, or the async victim signal</p><p>chances are it&#39;ll get you to your goal, proper or not</p>

@dd@ak.gensokyo.shop petite chip au chocolat or chipolatine

https://twitter.com/feefal_/status/1775535533688496230 https://gelbooru.com/index.php?id=10258586&page=post&s=view

<p>being a persistent little kitten, i have developed incredibly cursed adaptations to this. for example, the signals that are by far most susceptible to crosstalk are async controls (for SPI, SCK; for ONFI NAND, WE#/RE#; for Ethernet, TX_CLK) and the best way to mitigate that (i mean aside from Actually using things correctly) turns to twist the async control signal with a ground</p><p>(there are other ways, e.g. inline slew rate limiting resistors, but i&#39;m tired and exhausted and i don&#39;t wanna solder)</p>

<p>using <a href="https://mastodon.social/tags/GlasgowInterfaceExplorer" class="mention hashtag" rel="tag">#<span>GlasgowInterfaceExplorer</span></a> with the default wiring harness that has 20 cm wires is an incredible crash course in digital signal integrity</p><p>especially at higher pin counts (even SPIx4/quad-SPI) it has a very noticeable amount of crosstalk and you will encounter crosstalk related issues that will make no sense and will not be visible on a scope because connecting a scope makes them go away</p><p>these are very frustrating unless you have a dwarf fortress mindset equipped</p>