Go Down

Topic: Uno R3 with FTDI (Read 4406 times) previous topic - next topic

mojoehand

I have an Uno R3 that works just fine with the built-in USB interface. I have a need to test some PC software with an FTDI232 interface, instead of the 16U2 USB chip on the Uno R3. Looking at the schematic, the 16U2 TX/RX lines go to the TX/RX lines on the 328P and the Uno header.

I plugged the TX/RX lines from an FTDI board (that I know works with Pro Minis), along with a GND connection. The Uno is powered via the USB port, but the data lines are not connected, only power and ground. No matter which way I swap the TX/RX lines, the PC does not see the Uno with the FTDI board.

Basically, what I am trying to make is an earlier version of the Uno, but I don't have one on hand. This is for a one time test, to determine why some PC software isn't communicating.

Can anyone help?


ChilliTronix

Is it just for serial communication as opposed to programming?

Can you see the FTDI board in device manager and does it come up as a com port in the IDE?

johnwasser

If your PC can't see the FTDI chip as a USB Serial Port then the driver or chip is bad.  I hope you didn't use the FTDI driver on a counterfeit FTDI chip.  Some FTDI drivers will brick (make permanently useless) a counterfeit chip.
Send Bitcoin tips to: 1G2qoGwMRXx8az71DVP1E81jShxtbSh5Hp
See who has no social life: https://forum.arduino.cc/index.php?action=stats :)

mojoehand

I just want to do serial communications, no programming. I can see the FTDI board as a COM port. I can't talk to the Arduino.

I had read something elsewhere on the forum that indicated that what I want to do should work.

evildave_666

Are you holding the 16u2 in reset?

mojoehand

Are you holding the 16u2 in reset?
No, haven't tried that. Is there any easy way to do that, short of soldering a wire on the chip/board?

evildave_666

Ground the reset pin on the ICSP header FOR THE 16U2.

mojoehand

Ground the reset pin on the ICSP header FOR THE 16U2.
Thanks. I'll try that tonight.

mojoehand

Thanks. I'll try that tonight.

Holding the 16U2 reset low did not make any difference. I still can not communicate with the Uno, but the FTDI board is seen as a Com port.

evildave_666

Given that behavior the only thing I can think of is that the 16U2 merely being connected and the 1k resistor on the line might be causing the issue.  I'm not sure what the datasheet defines the logic level of the pins while the chip is in reset. My assumption would be the pins would be tristated but now I'm not sure.

krupski

I have an Uno R3 that works just fine with the built-in USB interface. I have a need to test some PC software with an FTDI232 interface, instead of the 16U2 USB chip on the Uno R3. Looking at the schematic, the 16U2 TX/RX lines go to the TX/RX lines on the 328P and the Uno header.

I plugged the TX/RX lines from an FTDI board (that I know works with Pro Minis), along with a GND connection. The Uno is powered via the USB port, but the data lines are not connected, only power and ground. No matter which way I swap the TX/RX lines, the PC does not see the Uno with the FTDI board.

Basically, what I am trying to make is an earlier version of the Uno, but I don't have one on hand. This is for a one time test, to determine why some PC software isn't communicating.

Can anyone help?


Buy yourself a Duemilanove. It's an Uno with the FTDI serial interface chip and, even better, it uses a real crystal for the CPU clock rather than the inaccurate and tempearture-unstable ceramic resonator that the Uno has.

And, they cost less than the Uno R3. Check out this link:  www.amazon.com/Arduino-Duemilanove-Board/dp/B004A7L3NC

You can even unsolder the 16M crystal and use a 20, 22.1184, 24 or 25 MHz part and "overclock" the board (try desoldering and re-soldering a teeny tiny resonator).

The board works great at 25 MHz... haven't had one yet that didn't.

The board that Amazon sells (the link above) is a genuine Duemilanove (or at least it's a good enough copy that I can't tell the difference). And for $20, you can't beat the price.
Gentlemen may prefer Blondes, but Real Men prefer Redheads!

mojoehand

Buy yourself a Duemilanove. It's an Uno with the FTDI serial interface chip
I already have some Nanos on the way. I was just trying the FTDI board with the Uno in the mean time.

Quote from: evildave_666 - Today at 02:28 am
My assumption would be the pins would be tristated but now I'm not sure.
I would think that holding the 16u2 in reset would tristate the outputs as well. It certainly does keep the Uno from showing up as a Com port in Device Manager. I tried the TX/RX lines swapped both ways and in either case, the Uno is not seen via the FTDI board.

I guess I'll just have to wait for the Nanos.

Go Up