Category Archives: serial port

Easy Portable Serial Ports

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Modern operating systems insulate us — as programmers, especially — from so much work. Depending on how far back you go, programmers had to manage their own fonts, their own allocation space on mass storage, or even their own memory allotments. Every year, though, it seems like things get easier and easier. So why is it so annoying to open a simple serial port? It isn’t hard, of course, but on every operating system it seems to be painful — probably in an attempt to be flexible. And it is even worse if you want portability. I needed to write …read more

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Secret Serial Port for Arduino/ESP32

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If you use the Arduino IDE to program the ESP32, you might be interested in [Andreas Spiess’] latest video (see below). In it, he shows an example of using all three ESP32 UARTs from an Arduino program. He calls the third port “secret” although that’s really a misnomer. However, it does require a quick patch to the Arduino library to make it work.

Just gaining access to the additional UARTs isn’t hard. You simply use one of the additional serial port objects available. However, enabling UART 1 causes the ESP32 to crash! The reason is that by default, UART 1 …read more

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Dummies Guide to Reverse Engineering

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[Juan Carlos Jiménez] has reverse engineered a router — specifically, a Huawei HG533. While that in itself may not sound substantial, what he has done is write a series of blog posts which can act as a great tutorial for anyone wanting to get started with sniffing hardware. Over the five part series, he walks through the details of identifying the hardware serial ports which open up the doors to the firmware and looking at what’s going on under the hood.

The first part deals with finding the one or several debug ports on the hardware and identifying the three …read more

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Quad Serial Adapter

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Despite concerted efforts to kill them, serial ports are alive and well, especially in embedded system. True, most of them end in a USB port, these days, but there’s still a lot of gear with a DE-9 (it isn’t a DB-9, despite the common use of the word) or a TTL-serial port lurking around. [James Fowkes] got tired of managing a bunch of USB to serial adapters, so he decided to build his own FT4232 breakout board that would provide four serial ports from a USB connection.

The small board has transmit and receive LEDs for each port along with …read more

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Cable Butchering For Logic-Level Serial

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Early PCs and other computers had serial ports, sometimes as their main interfaces for peripherals. Serial ports still survive, but these days they are more likely to have a USB connection into the main computer. However, when you are working with a microcontroller, you probably don’t want a proper RS232 port with its plus and minus 12 volt signals.

You can get converters that specifically output logic-level signals but you probably can’t pick one up at the local office supply store. They might, though, have a normal USB to serial cable. [Aaron] had the same problem so he hacked into …read more

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