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Building the worlds jankiest serial to USB cable from scavenged parts

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Re: Building the worlds jankiest serial to USB cable from scavenged parts

#11

Post by bartlettD »

Havoc wrote: post #10
alias_neo wrote: post #4

I'm not sure why I expected more, but I was a little disappointed. Soldering some wires onto an FTDI chip in a pinch is great, but the chip is doing all of the work really. I was hoping to learn I could make a serial to USB with _less than_ an FTDI chip. That said, respect for the effort of taking the photos and writing it up, and it was worth a read to learn about those naughty Scots bricking peoples devices with ba…

>expected more It's the field - very wide range of ability. Some are stoked about making LEDs blink and others are busy dumping and reverse engineering ROMs. Just depends on one's own journey stage. In my case article is above my level...haven't dealt with UART before

Agreed, its a nice accessible article for beginners. I can see someone who has really only played with Arduinos and Adufruit modules looking at this and getting some inspiration to try out some of the techniques he mentions.

For example, you'd be suprised how many practicing EEs I've met who aren't aware drag soldering is a thing. (Which is a fantastic technique btw, saves so much time and gets you much nicer joints than individually soldering )

Re: Building the worlds jankiest serial to USB cable from scavenged parts

#12

Post by m-ee »

bartlettD wrote: post #9
taneq wrote: post #2

Maybe it’s covered and I just missed it, but why disassemble the Arduino when it has perfectly serviceable serial ports? I mean, unless for fun, which is a valid reason in the context.

He's not using the Arduino Uno for anything useful, its just a test jig to check the cable works. He says at the start of the article that he needs a USB-UART converter to work with another project. I'm assuming that project doesn't have its own USB-UART like an Uno.

As the comments above mentioned he could have left the FTDI chip on the arduino board and just used it that way. Moving it to the breakout board didn’t do anything but save some space

Re: Building the worlds jankiest serial to USB cable from scavenged parts

#13

Post by crispyambulance »

tldr; for those who didn't bother to look for "an explanation" of why the wires were soldered directly to the pins of the IC instead of THE BREAK-OUT BOARD...

  > Now, you're probably thinking to yourself: "Why would you not just solder to the nice, big, widely spaced holes for the pin headers?", which is a fair question. I suppose this the one place I opted for a little less jank. You see, differential pairs actually require the length of wires and signal traces on a PCB to be carefully controlled. In theory, if the plus wire was a little longer than the minus wire, the two signals would arrive at the chip at very slightly different times. That would mess up the signal integrity, and maybe even prevent the device from working. All of that said, I'm almost certain that this wasn't required at all.

Re: Building the worlds jankiest serial to USB cable from scavenged parts

#14

Post by fstokesman »

unwind wrote: post #7

I thought this was a fun journey through a tiny DIY tooling project, and I enjoyed it! I liked the detail level which is turned up quite high, taking care to explain many of the steps that are (typically) taken for granted by electronics hobbyists. Still, this part stuck with me so I feel a need to comment: The high level overview is that "serial", or UART (Universal Asynchronous Receive and Transmit) is a protocol f…

You're absolutely right, I don't know why I had attributed the name to the full duplex nature. And of course, there is also USART, where you can have a separate clock line, which allows you to omit the start and stop bits too. At that point, you're essentially turning your UART into a single connection SPI bus.

Re: Building the worlds jankiest serial to USB cable from scavenged parts

#15

Post by fstokesman »

alias_neo wrote: post #4

I'm not sure why I expected more, but I was a little disappointed. Soldering some wires onto an FTDI chip in a pinch is great, but the chip is doing all of the work really. I was hoping to learn I could make a serial to USB with _less than_ an FTDI chip. That said, respect for the effort of taking the photos and writing it up, and it was worth a read to learn about those naughty Scots bricking peoples devices with ba…

Totally fair point. One of the videos I'm going to get around to making on my channel at some stage is a UART transceiver on an FPGA. Definitely not the "easier in a pinch" I was originally going for, but hey, if you've got the hardware hanging around!

Re: Building the worlds jankiest serial to USB cable from scavenged parts

#17

Post by fstokesman »

snvzz wrote: post #5
taneq wrote: post #2

Maybe it’s covered and I just missed it, but why disassemble the Arduino when it has perfectly serviceable serial ports? I mean, unless for fun, which is a valid reason in the context.

On top of that, it's enough to assert the microcontroller's reset to then freely use the RX/TX pins from the FTDI as if it wasn't there. Just plain insanity. As for cp2104 usb to ttl serial, full adapters using that chip cost $2 a pop on AliExpress. As the prices are like that, I ordered a few of every available usb-serial chip at some point. I'll be fine for a long time.

Indeed - I know I could have also popped out the DIP micro on the board and used it directly, but I choose not to for two reasons:

1. Its so much bulkier, and I wanted something that was the same form factor as my old unit 2. It seemed way more fun to do things this way, and I was pretty sure I could do the whole operation in less than an hour

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