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Topic: my own ft232rl circuit (Read 5011 times) previous topic - next topic

miros

Hi guys,
i have made usb to uart coverter with ft232rl but a had few problems abouth it. first capacitor C3 stared smoking a burning after connecting to pc  :smiley-eek:. then i realised that pin 4,5 on IC are connected together. could this be reason why the cap died? anyway after desoldering this cap and disconnected those pins, i conncted this circuit to PC and drivers installed, It made new port (COM7) and it seemed like it's  working. when i connected it to the arduino on my breadboard i couldn't upload sketch. after compiling it reseted arduino but it showed error and didn't upload. Is there anything wrong with schematic or something else? Can someone help?

Houser636

#1
Sep 25, 2012, 01:44 pm Last Edit: Sep 25, 2012, 01:58 pm by Houser636 Reason: 1
Is your rx going to tx, and tx to rx.  Sorry couldn't pull your schematic up on my phone, but thought this could be the case. This causes the driver to download ok, but wont be able to upload.  Also, do you have the dtr pin to the reset line?  It might not be automatically reseting to upload.

CrossRoads

Check your pin connections against the deumilanove schematic at the Hardware page.
If memory serves, you need Reset pulled High and Test connected to Gnd. There may be other input pins that need addressing also.
Designing & building electrical circuits for over 25 years.  Screw Shield for Mega/Due/Uno,  Bobuino with ATMega1284P, & other '328P & '1284P creations & offerings at  my website.

magagna

As Crossroads says, check your pins.

It looks like you're trying to power your circuit from USB. I recommend reviewing FTDI's "USB bus powered configuration" example from the FT232rl's datasheet.

A quick glance at your schematic shows a couple of potential problems:

You have VCC on USB pin 2 and ground on USB pin 3. That may be a nonstandard pinout of your USB socket but typically VCC is USB pin 1 and ground is USB pin 4.

You have a 10uf cap between 3v3 out and ground; the FTDI reference says it should be 0.1uf.

The FTDI reference says TEST should be tied to ground; you've left it floating.

Finally, the FTDI reference says you can leave RESET floating (as you've done) but the Arduino boards that use the FT232rl have it connected to VCC. I'm not sure what the implication of that is; I've never made a USB powered circuit that uses the FT232RL (all my designs with that chip have been self powered).

I hope this helps. Good luck!
http://en.wiktionary.org/wiki/magagna <-- My last name.  Pretty apt.

miros

thanks for replies. its working  8). just rx and tx was connected wrong. thanks for help anyway.

miros


(all my designs with that chip have been self powered).


my design is working but it doesnt upload everytime. first upload error second too and third success. would you be so nice and send me your schematic, please?

CrossRoads

#6
Oct 05, 2012, 09:02 pm Last Edit: Oct 05, 2012, 09:06 pm by CrossRoads Reason: 1
@miros,
Download the Duemilanove schematic from the Hardware page and use the FT232 design there.
http://arduino.cc/en/Main/ArduinoBoardDuemilanove

Or this one even, same thing for just the FT232
http://arduino.cc/en/Main/MiniUSB
Designing & building electrical circuits for over 25 years.  Screw Shield for Mega/Due/Uno,  Bobuino with ATMega1284P, & other '328P & '1284P creations & offerings at  my website.

CrossRoads

Do you also have 100nF cap between FT232 DTR and '328 reset? Do you have 10K reset pullup resistor to +5? Do you have a diode acros that resistor like current Uno's use (anode to reset, cathode to +5)?
Designing & building electrical circuits for over 25 years.  Screw Shield for Mega/Due/Uno,  Bobuino with ATMega1284P, & other '328P & '1284P creations & offerings at  my website.

magagna

Quote
my design is working but it doesnt upload everytime. first upload error second too and third success.


When I first started working with the bare FT232 I had this problem too...

Quote
Do you have a diode acros that resistor like current Uno's use (anode to reset, cathode to +5)


...but I've never seen the problem since I added a diode.

So hopefully that will fix your problem as well.
http://en.wiktionary.org/wiki/magagna <-- My last name.  Pretty apt.

miros

thanks i will try and post results later.

miros


Do you have a diode acros that resistor like current Uno's use (anode to reset, cathode to +5)?

anode to reset on atmega or on ft232?

CrossRoads

Across the atmega's reset resistor.
Description is backwards tho - anode on reset pin, cathode to +5.
Any spikes on the reset pin get dissipated to +5, and prevent the part from thinking it is going into high voltage programming mode.
See section 3.
Designing & building electrical circuits for over 25 years.  Screw Shield for Mega/Due/Uno,  Bobuino with ATMega1284P, & other '328P & '1284P creations & offerings at  my website.

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