To be or not to be ... USB-UART Adapter on your board - Page 1
Forum section: electronics / general

author: TJ232
author_rank: Frequent Contributor
timestamp: June 03, 2015, 10:18:47 am
content: Question : Why would you prefer to have the USB-UART adapter integrated on your MCU app/dev board not as a separate module? It's just a habit? A fashion? A simple way to fill the board with an extra value-added "smart" function?I personally prefer to have it separately, because in this way I can use the USB adapter with many different MCU Boards, just unplug one board from the USB adapter, plug the other in and that's it.I really would like to hear pros and cons about

author: ralphd
author_rank: Frequent Contributor
timestamp: June 03, 2015, 02:33:11 pm
content: I like my USB-ttl adapters as they are useful for more than just MCU interfacing, but with cheap USB chips like pl2303 and ch340g, there's little savings leaving it out. For example 328p nano clones are 25c more than 328p pro minis.For newbies a single USB connector is pretty foolproof compared to hooking up rx/tx and power with dupont cables.

author: suicidaleggroll
author_rank: Super Contributor
timestamp: June 03, 2015, 03:29:12 pm
content: It's much cheaper to integrate it onto the board than to use a separate cable. FTDI chips and USB device connectors are <$5 in low quantities, FTDI cables are upwards of $20-30. If you're the only one who will be interfacing with your devices, it makes more sense to purchase a single cable and use it with all devices. If you'll be distributing or selling these devices, it makes more sense to integrate the USB-UART adapter in the device so that you're not forcing everyone who buys one to also buy a $20 cable so they can talk to it.

author: nctnico
author_rank: Super Contributor
timestamp: June 03, 2015, 03:39:51 pm
content: If you need communication with the microcontroller on a regular basis then I'd have the microcontroller deal with a CDC implementation. I only go the UART - USB converter route if communication is necessary for every now and then. Adding USB to a board increases the price and complexity because you'll also need some EMC filtering etc if you want to do it right.

author: TJ232
author_rank: Frequent Contributor
timestamp: June 05, 2015, 04:35:05 am
content: Thank you guys for sharing your thoughts about.Now the next dilemma: -> Mini USB of Micro USB? That's the question today:)I prefer Mini USB for robustness (big fan of USB B but has become somehow obsolete for domestic applications) as I have seen an endless amount of micro USB failing badly especially on devices that will be plugged/unplugged frequently.Looking forward for your experiences about.

author: zapta
author_rank: Super Contributor
timestamp: June 05, 2015, 04:42:37 am
content: Quote from: TJ232 on June 05, 2015, 04:35:05 amMicro USB. Make sure to have the ones with through hole mounting tabs. We had a thread about this a few months ago.BTW, regarding the on board USB, it doesn't have to be a USB/Serial adapter. You can have a MCU that does USB directly, for example CDC virtual com port.

author: TJ232
author_rank: Frequent Contributor
timestamp: June 05, 2015, 07:38:46 am
content: Quote from: zapta on June 05, 2015, 04:42:37 amOK. Noted, MicroUSB. But WHY? What's your personal reason for choosing MicroUSBAre they still out there MicroUSB connectors WITHOUT through hole mounting tabs? Remember the disaster when first MicroUSB connectors hit the consumer market ?Yes, CDC might be an option for some applications, quite nice actually.

author: nctnico
author_rank: Super Contributor
timestamp: June 05, 2015, 02:05:22 pm
content: I use the B-type through-hole connectors in my designs because it is big which makes it easier to insert a plug.

author: krivx
author_rank: Frequent Contributor
timestamp: June 05, 2015, 03:03:08 pm
content: Quote from: mojo-chan on June 05, 2015, 11:54:14 amThat has to do with punching a retaining spring on the connector instead of the socket. Micro-USB connectors can still peel off the PCB if they are secured only by surface mount pads.

author: Bassman59
author_rank: Super Contributor
timestamp: June 05, 2015, 03:37:12 pm
content: Quote from: mojo-chan on June 05, 2015, 11:54:14 amthat's right, and the pile of bad Micro-USB cables I have attests to the shittiness of the design. The cable connectors last about ten mating cycles.

author: Bassman59
author_rank: Super Contributor
timestamp: June 05, 2015, 03:38:34 pm
content: Quote from: TJ232 on June 05, 2015, 04:35:05 amIf it's for a dev board, or really any project that is not particularly constrained by size, just use the standard old-school Type B connector and be done with it. Compared to the smaller connectors, they're indestructible, and cables are readily available (you probably have drawerful of them already).=a

author: zapta
author_rank: Super Contributor
timestamp: June 05, 2015, 03:52:25 pm
content: Quote from: TJ232 on June 05, 2015, 07:38:46 amSmall and popular. This way I need only one kind of cables.Quote from: TJ232 on June 05, 2015, 07:38:46 amYes. For examplehttp://www.digikey.com/product-detail/en/10104110-0001LF/609-4052-1-ND/2350358Having vias in the mounting pads helps. Some Mini B also do not have through hole mounting tabs. I have for example a Sparkfun FTDI Basic with peeled on connector.I use micro USB everywhere, often with cheap Chinese cables and no problem whatsoever. I like the colored flat ones, do not tangle and easy to trace. $9 for a set of 10 shipped from Amazon.

author: Simon
author_rank: Unknown
timestamp: June 05, 2015, 09:23:05 pm
content: We had this very discussion at work with our a subby designer (and member of this forum) and decided that we would use an ftdi cable as there was no point in designing in an ftdi chip and have the board space committed for production, the MCU does not have built in USB anyway.

author: c4757p
author_rank: Super Contributor
timestamp: June 05, 2015, 09:57:10 pm
content: Quote from: Simon on June 05, 2015, 09:23:05 pmYeah, it's different for a debug port or something like that. When it's part of the primary function of the device, just use a USB microcontroller FFS. But for a debug port, UART is easy to get running and uses minimal microcontroller resources.

author: Monkeh
author_rank: Super Contributor
timestamp: June 06, 2015, 07:17:47 am
content: Quote from: Bassman59 on June 05, 2015, 03:37:12 pmAn interesting claim, as I have many cables with hundreds of cycles. I don't think the design is at fault.