Quad Serial Adapter

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 EMI and ESD protection on the USB port. The ports are all TTL serial, serving the modern hacker, and the 3.3V pins are 5V tolerant.

This is one of those things that isn’t very difficult to do, but is super handy. Having it all on a well thought out board ready to go, is a time saver.

If you long for the old parallel port, FTDI devices can do a bit bang mode. If you are really paranoid about protecting your USB port, you might consider using galvanic isolation.

31 thoughts on “Quad Serial Adapter

    1. I was thinking the same thing. FTDI is dead to me. I refuse to support them. people here, of all places, should GET that.

      also, what’s wrong with calling the connectors db9? even ftdi’s docs call them db9. everyone calls them that. iirc, mouser and digikey do too?

      so, what’s up wid dat?

        1. Taking the “correct” route is not going to help you find the best solution. A simple Google search shows that you should be using DB9 because searching for DB9 connectors results in nothing but pages and pages of data about what you’re looking for, yet searching for DE9 produces mostly encyclopedia entries, blog posts, and comments about how it is the “correct” form and why.

          Yes it’s correct. No being correct is not a benefit here.

    2. I too gave up with FTDI but I do miss the obscure baud rates you could do with them that you can’t do with the CH340.

      I suppose if it bothered me that much I would go and find another one that could do it but for sure FTDI are now history to me.

      1. I have no issues with ‘non-standard’ baud rates using the prolific pl-2303. Especially in the higher bitrates like 250kbaud, 1Mbaud etc. it’s essential since most mcu’s can’t produce the official baudrates without uart crystals.

        I’m not sure I’d use a quad serial interface, I’d rather use one and send all data over that. Using commands you can separate out the data easily. If you need more throughput or concurrency though, it could be handy.

    3. Yup, FTDI is horrible. How dare they not support fake clone chips. They need to support the companies that steal their drivers and undercut them.

      If you were in there shoes, and random people were getting pissed with THEM for chips that they did not actually make, giving them a black eye, then you might do the same thing.

      If guys in China want to make cheap USB-serial chips, good for them, but let them develop their own drivers for it and at least be honest about what they are making.

  1. hum ftdi deserve to protect their investment and research, If you want to complain, tell this to the FTDI knock off chips makers instead …

    I buy genuine FTDI products, never had any problems, had clone chips who had baud rates problems and communications failures ….

    You know about FTDI or Silabs drivers, do your search before buying anything, that’s all …. OR buy ch340 based chips / dongles etc …

    1. do we REALLY have to educate you about all this.

      look, as much as you think you are sure about it, you cannot be sure that some supply chain slips fake chips into boards you design. and then what, smart guy?

      no, no one should be buying ftdi anymore. and I would prefer to avoid to buy from companies that EMPLOY people like you who don’t understand simple things like fake chips in supply chains being impossible to defeat entirely. you must not care about your customers.

      tell me which company you work for so I can avoid your designs, please.

      1. FTDI was in a damned-if-you-do-damned-if-you-don’t situation. The knockoffs pretending to be an FTDI chip were already buggy, and already dragging their reputation down. So they could shrug, cry, lobby for some kind of anti-counterfeiting law, and/or they could just nuke everything.

        Was choosing the last one worth it? Clearly it dramatically hurt end users and small-run manufacturers. But it’s not clear that any of the other choices would have really been any better for FTDI.

        1. we should not rehash the whole ftdi-gate thing all over again, but their treatment of end users showed me that they were not a company to be trusted to do the right thing. perhaps they thought they were doing right for themselves, but overall, they got nothing but bad publicity and blowback from it. even if I could buy real chips for fake prices, I would still not do it. their drivers are hostile malware and that’s that, full stop. no more buying ftdi. shame, but they picked their own destiny. other chips get copies and few companies go full retard on their end users like ftdi did.

          1. Funny – Apple regularly screws its customers through software updates yet nobody here is complaining about Apple products. Software updates are used to cripple older hardware and prevent users from using perfectly good devices or from allowing them to install new software. Apple isn’t the only one doing this. The phone companies prevent our android phones from updating because we really have no need to upgrade hardware as often as software updates.

        2. “FTDI was in a damned-if-you-do-damned-if-you-don’t situation.”

          No they weren’t. They had plenty of means of identifying counterfeit chips clearly so they could have empowered integrator to analyse and take control of their supply chain. Instead they attacked the customer’s of integrators. It was worse than doing nothing.

  2. Thank you thank you for knowing your D shell sizes. It always grates on me when someone says “DB-9” (except for the weird connector I once saw that really DID only have 9 pins but was in a huge B shell.

  3. For those “smart asses” who easily blame others without knowing …

    I work at a medical electronic design and production facility, (by the way, i have 30 years of electronic background) we have to check for genuine and fakes parts in every machine or equipment we make, it’s our responsibility to have reliable equipment … when the lives of people depends on the products we build.

    It’s not about FTDI, it’s about every components we buy and install.

    We have fakes caps, fake crystals or recaped ones, fake “badged” processors, and the list goes on and on … Google is full of those histories.

    By the way i don’t need to be educated, like ” x y z ” who gives stupid answers around here loll

    Will you be happy, if you buy a fake computer processor ?? fake ram specs, or even brand new hard drives who had hidden viruses on the boot sectors, software’s who had back doors,
    A perfectly good server motherboard, who cost around 700$, fail due to a mere 1$ part ??

    I have seen a lot, and will see more of that.

    This is getting off topic i wont reply anymore.

    1. So you are saying that I can open up anything that I buy a a store and not void my warranty and check to see if there are any fake things in there.
      I dont think so..
      And I all so worked at a hospital for over 10 years and the med Tecks do not have the time to open up every device that comes in. And then there is management that are trying to save every bloody dime and bring things in that are not csa and all that into the hospitals. And now you have new Hospitals that have more electronics in everything. exm. All most every door in the hospital can have over 70 connections to it.
      I all so told them that the light system can be hacked very easly. That all so includes the ORs. They dont care it is all about money now.
      Who cares about safety..Ive seen so much of it, way to much, it makes me sick!!!!!

    2. “we have to check for genuine and fakes parts in every machine or equipment we make”

      So? Go for it. Nothing’s stopping you. FTDI may even be able to help you identify counterfiets since they clearly have the means.

      What’s this got to do with bricking or rendering end user devices inoperable again? If you continue to excuse this behaviour then we’re all glad you won’t be replying anymore, at least the level of common sense would increase around here.

      1. It was 3 am Im up in pain can harly move, drugs not working yet. dead tiered but cant sleep and pissed about life.
        SORRY
        I am very sorry. I will try not doing anything like these again.

  4. I’m curious about this. I work in the enterprise firmware world and we use serial ports a fair amount for a number of things (they are dead simple to get data into and out of). I’ve tried the 895-USB-COM232-PLUS4 module and it’s OK with Windows, but I tried using it on a RasPi with ser2net to make the ports remotely accessible. I kept having problems with the connections getting dropped and it seems it’s a combo of the hardware being sensitive to noise on the serial ports and the drivers on teh Pi not being able to cope. If this adapter is better, it’s worth watching.

  5. It’s the cry baby brigade again whining about their counterfeits not working. Boo hoo. I bet you whine at customs too when they impound your three dollar nikes. FTDIs real customers applaud their stand against counterfeits and will keep them in business.

      1. And you should lay your damage claims with them if you have indeed gotten counterfeits from them. If everyone remains idle you are just sponsoring counterfeiters. You should aim your anger at them and not at companies who design desirable products.

        1. Right. We should start a complex and lengthy international lawsuit over $1000 worth of parts. We’ll end up spending $150K on lawyers, and in the end they’ll refund our purchase because of their TOS.

  6. In my experience FTDI devices have always been rock solid, very well engineered, well documented, with solid no-fuss driver support on every major OS and plug-and-play experience that just works.

    The FT230XQ, which I most commonly use at present, does what it needs to do very reliably, at 3.3V, with essentially no external components, in a very compact 16-QFN package. No crystal, low overall BOM cost, minimal board space.

  7. I am yet to suffer a bricked ftdi part but have suffered at great lengths the pathetic ch340 drivers.

    But that aside its interesting the amount of devices that are built everyday that rely on converting USB to rs232.

    Maybe we should be learning to work natively with USB (if that is in fact possible )

    1. There’s already the USB CDC (Communications Device Class) spec… anyone can make a USB-RS232 device using that spec and it has built-in drivers in most operating systems (strangely, it needs a .inf file in Windows). Why these devices don’t follow USB CDC, I have no idea. Probably so they don’t inter-operate with each other, so you get locked in to a specific vendor.

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