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Good alternative for FT232RL for USB->Serial conversion?


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I am looking for the most efficient way to output serial data to a PC via USB. FT232RL is one alternative, but seems overpriced for what it does (~$5 on mouser, $3.50 on ebay with shipping from China). Are there cheaper chips that still work reliably and have default support on Windows and Linux (Mac would be nice too)? Somehow it feels wrong to spend more on a serial interface than on the microprocessor that's outputting the data.

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Recently I use assembled modules with SiLabs CP2102 for under 3$. So far I didn't have any problem with them on Windows or Linux. If you need only chip it's possible to get 10pcs under 20$ on ebay. I think cheapest chip is PL2303, it's like half the price, but it requires external crystal. I got some RS-232<->USB cords with PL2303 and it didn't turn out to be the best solution. Maybe it wasn't caused by the chip itself but it's implementation.

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Well, for starters, DO NOT use the TUSB3410VF which is already on the launchpad. It is a chip sent from hell to make your life miserable if your using a more modern OS such as W7. I've cried and pleaded with TI but all they tell me is that its not necessarily W7 compatible on all machines. There is probably a more intelligent answer out there as well as a solution but I haven't had time to look into it further. In any event, its going to be hard to find this chip cheaper than a FT232RL so I apologize for the rant.

 

The FT232RL is a beeaauttiffulll chip simply due to the compatibility and reliability of the FTDI drivers. Yes, its pricey, but you most certainly get what you paid for in comparison to other chips on the market. Now, one thing to consider is who your buying it from and in what quantity. Digikey generally = most expensive. Where as if you get them from ebay, you can get them for 2.88 usd. per chip in QTY of 10: http://www.ebay.com/itm/10PCS-IC-FT232R ... 3a747d0e9e.

 

The MCP2200 is another possible option that i've used abit in the past. It was reliable on W7 at least for what I did with it. However, that doesn't guarantee compatibility on all common OS-es or ensure longterm reliability when sending thousands of packets for an extended duration of time. In addition, this chip requires more external components such as a crystal oscillator. This makes it harder to prototype and not necessarily as cheap as it seems. If thats not a problem for you, mine as well try it out and save a few bucks.

 

USB itself is not necessarily a cheap application and especially for a unique driver application. Only reason industry can get away with such cheap products is because of quantity. In a quantity of 1-10, i'm not sure there many solutions cheaper than ~2usd.

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FT230X ($2.30-ish on Mouser).

 

"According to oPossum" :).

 

Generally speaking, do yourself a favor and go with FTDI. Specifically, if you think you will ever need to plug more than one of them in the same host at the same time and be able to distinguish between them, go with FTDI (none of the others include a device-specific unique identifier).

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FT230X and FT231X are much less expensive than the older FT232R. Still a bit more than some others, but often less hassle to get working. No external xtal or EEPROM required on R and X series. (B, H and other series do need more support components)

 

I have designed a few BOBs using the new X series chips. I can post the Eagle files if you are interested.

 

The genuine Prolific PL2303 is quite good. It uses an extended CDC ACM protocol to provide full handshake line support (requries Prolific drivers). The clones of the PL2303 tend to be bad to horrible. They are often found in cheap cell phone cables (Nokia CA-42 and such) and many of the translucent blue USB to serial cables. "Code 10" on the Windows driver suggests you have a clone and not the real deal.

 

The SiLabs CP2102 had some driver problems the last time I tried to use it (~4 years ago). Don't know if that has been fixed.

 

The Microchip MCP2200 uses CDC ACM, so the support for handshake lines is limited and their implementation is a bit unusual.

 

The TUSB3410 has a bit of a bad reputation because the Launchpad application UART is not reliable. This seems to be specific to the firmware used with the Launchpad, using other firmware may offer much better performance and reliability, but is still limited to what CDC ACM supports.

 

So the only chips I can recommend without reservation are any of the FTDI chips and a genuine Prolific PL2303.

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I've said it before and will say it again: there is nothing better (that I know of) than the FTDI chips. You don't really pay for the ICs but for the work that went into the drivers, which are a breeze to work with, especially when you are using Windows. The fact that they are WHQL certified (~$1000 value for every driver release), and that you can program your own identifier string with free tools from FTDI (making them pop up in Windows driver installation as whatever you want) is worth the money for commercial applications. You can even integrate them seamlessly into a Windows Installer package for another application, so a costumer won't even really notice he is installing a third party driver.

 

Cheers

TomKraut

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