Projects and Gadgets

[Jon Chandler]

As I was putting the finishing touches on an external USB-UART adapter for the TAP-28, one of the adapters I ordered from Ebay arrived. It had been a couple weeks since I had ordered it, so I didn't remember all of its features. It actually has the major features I was designing into my adapter, at a price that can't be beat. It's around US$6, including shipping.

It's called a "USB 2.0 to TTL UART 6PIN Module Serial Converter CP2102". offered by Y & L Cabin. It's a 0.5 * 0.75" board with a CP2102 chip, a USB connector on one end and 6 header pins on the other. Not much to it but everything it needs.

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The second picture above shows the connections: Ground, TxD, RxD, RST, and 3.3V or 5V. It will supply either voltage from the USB interface. This of course makes it perfect to power a TAP-28 board equipped with an 18F25K20 to run Amicus code. It's also useful any time you want to have a serial interface to a PC without the need for using the PICKit 2 UART tool. You can use it with any terminal emulator or even interface to it using software that recognizes a COM port.

The picture below shows the interface in use with a TAP-28 board running Amicus code on an 18F25k20. It's powered only by this USB interface. Pretty slick! The LED on the adapter shows that it's connected to the PC and active (i.e., it's been properly enumerated).

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[Graham Mitchell]

What a great find Jon

How did everything go with the PC side of things? Were any drivers needed?

[Jon Chandler]

The CP2102 is a Silicon Labs chip. On the laptop, I needed to install a driver, which was conveniently included with the adapter on mini-CD. On the desktop, it was instantly recognized so the driver had been installed sometime in the past. Both computers are running Windows Vista so the drivers are current.

It looks like there are Mac and Linux drivers on the Silicon Labs web site.

[Graham Mitchell]

Outstanding. At that price, it looks like installing a female header to accommodate the USB-UART adapter would be a lucrative option.

[Jon Chandler]

In the case of the TAP-28 board, the pinout isn't quite the same as what the PICKit 2 needs.

The best bet might be to install a length of cable on the adapter to the appropriate 6 pin connector. The adapter is designed to plug directly into the USB port - I used an extension cable so I didn't have to plug it into the USB port directly. The board is narrow enough to fit with other USB cables. It could be covered with a piece of heat shrink after a cable is attached.

[Jon Chandler]

I actually got 2 USB-UART adapters today. The second one is a finished cable with a pigtail. It's supplied with female pigtails but you have to solder those on yourself.

This adapter features the Prolific chipset, and was easy to install also. Again, one computer had the driver, the other did not, but it was the opposite way around.

This converter has the advantage that it's a finished cable. It would be great connected to a board in an enclosure. On the down side, this adapter has only a 5 volt supply for the USB connector.

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This cable also came from Ebay, with the title "2 x PL2303 USB/TTL/RS232 Serial Port Converter Module" from xscyz. 2 cables were a total of just under $13 including shipping, so the price for either adapter is about the same.

[Graham Mitchell]

Another great find, though I'm leaning toward the first one. I think its the 3.3V support that nudges it through

[Jon Chandler]

The Prolific adapter is the one I used for the revised signal generator.

I thought it was limited to supplying 5v but after carefully opening the snap-together housing by tripping over the cable, I found that it also has a 3.3volt connection like the CP2102 adapter.

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and to answer a question I know you'll ask....no, the CP2102 adapter won't fit in the Prolific shell - I tried.

Jon

[be80be]

I think mine is better LOL I made it myself. That makes it highly adaptable like
1. you can add the code to any chip that has usb on board
2. Make just a stand along adapter
3 Could also make it put out real rs232 but that part I would have to do some real thinking like a buck-boost inverter. But that is doable to.

I nice usb to serial adapter thanks to the people who wrote Jallibs

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I have to love Jalv2 It has usb and it's some what like swordfish it's modular called jalibs

Them people at jalib wrote some nice drivers works with C18 too

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And here I'm talking to my self agin LOL

Here I'm echo input character

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