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...
This small key pad like circuit with an input shift register (74HC597) is a test circuit for input shift register. The shift register is parallel in and serial out register. The serial part is handle by the micro controller. For this test my friend wh0kn0wz was helping with bug in micro controller code. Thanks to him for identifying it. :P
This shift register can be used in key pads and other multiple controllers.
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