Cheap Chinese serial USB dongles

Questions on UARTs, and serial communication
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Client9
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Cheap Chinese serial USB dongles

Post by Client9 » Fri Aug 16, 2013 7:30 pm

While I have Coridium and SparkFun USB dongles, I thought I'd order some of the cheap ones from China on ebay.

The first of the FTDI types came in today, and it works fine for BASICtools. At the going price of $7 and $1 shipping, they are a bargain if you can wait a few weeks for delivery. While they will download C programs with either MakeItC or Flash Magic, you will have to manually hold the ISP BOOT pin low during the download cycle.

So if you are doing C development the Coridium version is still the way to go, just less hassle over the long run.

Still waiting for a $2 CP2102 USB dongle, with free shipping. I guess they make it up in volume, most likely they are scrapped units, but even then shipping within the US is just under $2 and for us to ship to China costs just short of $7.



basicchip
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Re: Cheap Chinese serial USB dongles

Post by basicchip » Wed Aug 21, 2013 3:45 pm

Good to know the cheapo dongles from China work, at least the ftdi ones. I'd be interested in hearing about the CP2102 versions, as those seem to be almost free.

I guess I could make loadLPC launch the downloaded code from the ISP, which would make the C debug cycle a little friendlier. Then you could leave the load C jumper on while iterating your C code. Then you would only have to remove it when you have debugged code you want to run from reset.

Client9
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Re: Cheap Chinese serial USB dongles

Post by Client9 » Wed Sep 04, 2013 1:47 am

Just received the $2 CP2102 based version of a USB to serial link.

While it does send and receive characters to a SuperPRO, the RST line at least on this board is an input, so there is no way to assert a RESET from BASICtools without some re-wiring.

The connection is done with 4 jumper wires, and the board itself is designed to plug directly into an USB A socket, so unless you can live with a 6 inch connection you will need a USB extender cable, something I normally don't carry around in my bag of trix.

I loaded the latest CP2102 driver, and looked at the datasheet. As this is a QFN pack, it would be difficult to add the wire, not impossible, though for a couple extra bucks you can get a ready to run FTDI version from China on eBay.

I always need a backup USB/serial connection either to monitor something or just for use after a program has been developed. So it is not a complete waste of $2. But it would not be my first choice.

basicchip
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Re: Cheap Chinese serial USB dongles

Post by basicchip » Wed Sep 04, 2013 3:56 pm

Does the CP2102 show up as a VCP or FTDI serial port?

That means BASICtools would recognize it and give it a name in upper case letters, vs lower case.

Client9
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Re: Cheap Chinese serial USB dongles

Post by Client9 » Thu Sep 05, 2013 2:55 pm

The CP2102 shows up in the BASICtools ->Options->Serial Port as com12 on my machine. Lower case letters.

kochevnik
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Re: Cheap Chinese serial USB dongles

Post by kochevnik » Wed Sep 18, 2013 3:49 pm

There are 6 pin CP2102 usb serial converters that have all the other pins broken out - I think it is the DTR pin that is needed for serial programming of the BChip. They are about $3 with free shipping, I bought a couple but have not tested them yet. And there are now CH340 chipped usb serial converters for $1 shipped - but wont actually program the Bchip but would work ok for serial comms I think.

ebay item numbers 190603151876 & 140751888486

basicchip
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Re: Cheap Chinese serial USB dongles

Post by basicchip » Sun Nov 16, 2014 2:12 pm

Before the latest hooplah about counterfeit FTDI chips, I bought some really cheap dongles from eBay. They just came in and I knew I would have to change the connector as these were males, and our cards expect females. But with some quick solder surgery I swapped the connectors. While they have to go on reversed they are functional for BASIC. So if you are real cheap the $2.94 seem to work if you have the female connectors and don't mind swapping them out. Personally I would buy the $6-7 and save the 15 minutes.

Here is the connector swap--
cusb1.jpg
cusb1.jpg (47.53 KiB) Viewed 8105 times
And how to connect to one of the boards
cusb2.jpg
cusb2.jpg (51.4 KiB) Viewed 8105 times
I updated the drivers to see if either were not real FTDI parts, but both seem to be fine. So these work fine for BASIC, but they do lack the second control pin used to put the NXP part into ISP mode for C programming. Though this one runs all pins to the edge so you could jumper it over.

AMDlloydsp
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Re: Cheap Chinese serial USB dongles

Post by AMDlloydsp » Sun Nov 16, 2014 11:56 pm

As this is a QFN pack, it would be difficult to add the wire, not impossible,
----------------------------------------
If the lead isn't broken out to somewhere else on the board, yes. It would require "some precision". But if it goes anywhere from the chip, it should be easy to skin the solder mask off a run, and tack to that.

I've had to do some mods, even to the Coridium dongles, in order to allow them to remain present in permanent installations without having to be connected to a USB device to allow them to boot. (documented here [somewhere] on the forum...)

Ah... here: http://www.coridiumcorp.com/forum/viewt ... ?f=4&t=738

Lloyd

basicchip
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Re: Cheap Chinese serial USB dongles

Post by basicchip » Mon Nov 17, 2014 3:38 pm

Actually this is a TSOP28 which is still a challenge to solder to, but the pins are brought out to 0.1" holes.

Problem is, I soldered the wire on to add RTS to the 6 pins (no need to cut CTS as it is an input). When I reconnected the part the PID was reset to 0000 which is the symptom of a counterfeit FTDI part and it no longer works with my updated PC. So it was working until power was cycled and a new ID was read.

So if you want to use these, don't update the drivers, which I did intentionally to see what the issue was. This was on a Win8.1 machine which has been routinely automatically updated, but the driver looks like it has to be specifically updated to 2.12.0.0 to disable these. So for now I can't use these on my main machine, but can be used on other boxes around here.

basicchip
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Re: Cheap Chinese serial USB dongles

Post by basicchip » Tue Nov 25, 2014 7:40 pm

After spending way too much time on it, I did get both real and fake FTDI devices running on Win8.1 even with the new driver installed.

I can understand FTDI wish to protect against counterfeits, though I don't really think they should brick other devices. For that reason I won't put the steps here, but they can be found out there on the web.

Moral of the story is if you want to use one of these ebay USB serial devices do not update your drivers past 2.10.0.0. I can't believe FTDI really cares about the handful of devices sold on ebay. I went through this excercise to see what was out there, not that we will buy more than a handful of these.

We will continue to build our USB dongles with FTDI devices we buy from Digikey which should be genuine, though we actually have been switching from the FT232RL to the FT231 which is cheaper.

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