USB-UART bridge chip recommendations? - Page 1
Forum section: electronics / general

author: Unknown
author_rank: Unknown
timestamp: October 15, 2015, 04:10:04 pm
content: I want to pick a USB-UART bridge IC for a microcontroller project (MCU will talk UART; USB to a PC).There seem to be hundreds of different bridge chips out there. I know FTDI is the popular one, but I'm looking for:* Small footprint (internal oscillators, minimal additional parts)* Support of 460,800 baud* SimpleNice but not critical:* Support of hardware flow control (RTS/CTS)* Support of USB-C connector (well, it would be nice; maybe too early for that)Cost is not a big issue (it's a hobby project, so I won't be buying a lot of these).Any suggestions?(Is there some web site that has a good index of what parts are available, to help narrow it down? Looking at distributor sites, they don't seem to list all the above details in their catalogs - you have to read each datasheet one by one.)

author: westfw
author_rank: Super Contributor
timestamp: October 16, 2015, 05:50:35 am
content: Is there a good reason that you don't want to use one of the existing (and very inexpensive) modules? A lot of them have similar or identical pinouts, so you can experiment and make sure there is a hardware/driver combo that you like.IMO, the FTDIs are still good products, if you're careful to get non-counterfeits. Various people are mad at the company, for their "driver bricks counterfeit chips" driver. Their newer chips (FT230X/FT231X) are smaller and cheaper. AND there are official, tiny, modules...CP2102 and Prolific are common choices as well, but the "counterfeit" landscape is confusing. ch340g is a newer Chinese Chip a a relatively friendly package (SOIC), but it needs an external crystal, and I don't know if you can find a "real" vendor.Microchip has a chip that is actually a pre-programmed PIC microcontroller, and so is potentially "fixable." (also needs a crystal. But newer PIC microcontrollers don't. Go figure.)

author: lod
author_rank: Contributor
timestamp: October 16, 2015, 01:51:02 pm
content: Something you should consider, especially if you are distributing these at all is OS support.Different devices offer different solutions to Windows driver support, much nicer if an external driver isn't required.They all tend to come up as a generic device on Linux and friends, so better support there.I have also had difficult in the past pushing high baud rate (1MB was definitely a problem) data down a Windows terminal device, not sure if it is still an issue.USB-C is just a new plug which wraps a standard USB 2.0 data pair so any USB chip will support it.Honestly in your position I would just go with the latest FTDI chip.They are popular and ubiquitous for a reason, you don't have any special requirements they don't meet, they are easy to get, well understood and easy to get support.

author: nctnico
author_rank: Super Contributor
timestamp: October 16, 2015, 02:00:15 pm
content: In my experience the CP210x chips are more stable in a noisy environment. I can reproduce the difference in reliability on my workbench so this is definitely not hear-say. My chip-of-choice is definitely the CP210x even though it is slightly harder to solder.

author: stevenhoneyman
author_rank: Regular Contributor
timestamp: October 16, 2015, 03:21:18 pm
content: FT230X: easy-to-solder for beginners, and driver support & compatibilityCP2102/CP2104: smaller physical size, and much lower cost

author: Unknown
author_rank: Unknown
timestamp: October 17, 2015, 04:02:47 pm
content: Thanks for all the answers!Soldering small-pitch SMD is no problem for me.Does the CP210x require a special driver on Windows, or does it work out-of-the box?Any opinions on the Microchip MCP2221? It seems to have an internal osc, and is small (as small as 4x4 mm in a QFN).

author: Jeroen3
author_rank: Super Contributor
timestamp: October 18, 2015, 12:22:56 pm
content: If you do not want a driver, get the UART-HID bridge from Silabs.

author: hamdi.tn
author_rank: Frequent Contributor
timestamp: October 22, 2015, 05:19:08 pm
content: most mcu now have embedded usb controller, an code available for usb to uart bridge ( at least what i saw with microchip and st) i think you can choose any one of those chip that meet your need and build one on your own.But none of them support USB with internal crystal.so if you are not limited by your mcu choice for this project , i think it will be good to pick one with usb and you don't need any bridge.

author: Gyro
author_rank: Super Contributor
timestamp: October 22, 2015, 06:14:46 pm
content: You might want to check out this thread, it was started at the height of the FTDI driver bricking episode and compares the strengths and weaknesses of probably every USB-Serial solution known to mankind.https://www.eevblog.com/forum/reviews/alternatives-to-ftdi-usb-to-uart-converter/

author: andersm
author_rank: Super Contributor
timestamp: October 22, 2015, 06:18:49 pm
content: Quote from: hamdi.tn on October 22, 2015, 05:19:08 pmThere are MCUs that do USB without a crystal, eg. Atmel's SAM D11 or ST's STM32L052.

author: hamdi.tn
author_rank: Frequent Contributor
timestamp: October 22, 2015, 06:45:21 pm
content: Quote from: andersm on October 22, 2015, 06:18:49 pmmy mistake, i was talking about the ones i worked with or saw their DS.

author: JTR
author_rank: Regular Contributor
timestamp: October 24, 2015, 01:49:44 am
content: Quote from: andersm on October 22, 2015, 06:18:49 pmAnd about a dozen or so PICs also are fully spec'ed to work without a crystal...

author: AlxDroidDev
author_rank: Frequent Contributor
timestamp: October 29, 2015, 01:34:01 am
content: Quote from: stevenhoneyman on October 16, 2015, 03:21:18 pmI also vouch for the CP2102.

author: richardman
author_rank: Frequent Contributor
timestamp: November 03, 2015, 08:57:53 am
content: My own experience with USB-UART CABLE is that the CP and Prolific chip cables do not work on my particular need (a CAN232 dongle) whereas the FTDI-based cable works great. YMMV. Since price is not a consideration, I'd just go with the FTDI

author: nctnico
author_rank: Super Contributor
timestamp: November 03, 2015, 12:17:02 pm
content: Quote from: richardman on November 03, 2015, 08:57:53 amThere can be differences in timing between the various USB-serial dongles. The fact the creator of the CAN232 software didn't care to test his CAN232 dongle with other USB-serial bridges doesn't make the FTDI ones better! It is just dumb luck. Given the fact you can run into fakes which are then rendered useless by the driver without warning and the FTDI chip is prone to erratic behaviour FTDI isn't even on my list.