It Started With a Hardware Limitation I have been using Quectel GNSS modules in my designs for a while. They are reliable, well-documented, and the support ecosystem is solid. But the module I had been using had one problem that I kept running into: no external antenna support . For most projects that is a minor inconvenience. For a marine vessel monitoring and control system , it is a non-starter. A vessel hull blocks sky view, antenna placement is critical, and the difference between a clean fix and no fix at all often comes down to whether you can mount the antenna where it actually has line of sight. An integrated antenna in a sealed enclosure below deck simply does not cut it. So I went directly to Quectel. The Conversation With Quectel I reached out through their official sample request channel. I was not expecting much — most component manufacturers have a standard process: fill out a form, wait, get a few uni...
When you use microcontrollers and you are out of PIN's to connect some LED's for status or when you want to drive a binary clock with few pins left in microcontroller, there is a way that can solve this issue. Its called charlieplexing and if you know multiplexing you will have some idea of how it works. I will do an example using Arduino for demonstration. Charlieplexing is a method to drive multiple LED's with few pins available in your microcontroller. Here is the formula to calculate how many LEDs can be drive from N number of pins. Number of LED's = No. of PINS available ( No. of PINS available - 1) For example you have only 3 pins left in Arduino and you want to know how many LED's can be drive. Number of LED's = 3(3-1) Number of LED's = 3(2) Number of LED's = 6 So from 3 PINS you can drive 6 LED's. Since arduino have tri-state output (INPUT, HIGH and LOW) its easy to drive the LED's using this method. how leds are connect...