FTDI cable

Forum 2005-2010 (read only) Hardware Troubleshooting
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I went and did my own ftdi cable.

I made it just as it is made in arduino schematic

C1,C2= 100 nF
R4,R5= 100 ohm
and there is 1k ohm resistor on tx and rx line which i forgot but soldered it on the circuit later.

Windows does recognise it and it even works throught telnet by bricking rx and tx.
And yes i do know rx and tx lines has to swap when conected to arduino.

ftdi Rx------- arduino Tx
ftdi Tx------- arduino Rx

I get following error

avrdude: stk500_getsync(): not in sync: resp=0x00
avrdude: stk500_disable(): protocol error, expect=0x14, resp=0x51

I tried it on 2 diffrent circuits and now ill try it on a barebone arduino, will report later.

2

Tried it on a minimal/barebone arduino on protoboard didnt work.

Any suggestions or any 1 misses/see something wrong on the schematic?

3

The easiest check if to not connect it to any arduino. Just wire a jumper from the rec to xmit at the connector pins. Now plug in the cable to the PC and first see if the PC announces the connection. If so, then open the Arduino IDE, select the proper comm port and then open the serial monitor. Anything you type in the output window and send should be echoed back into the receive window. If that works then just make sure about the RTS/DTR resistors sizes (should be 100 ohms) as that is how the auto-reset is activated before an upload can proceed.

Lefty

4

Rx and Tx works.
Is it normal for DTR to output 0.6V and RTS to output 1.8V, when i try to program?
I suspect i got an faulty chip.

5

Is it normal for DTR to output 0.6V and RTS to output 1.8V, when i try to program?
I suspect i got an faulty chip.

1.8vdc doesn't sound normal. It's hard to troubleshoot the auto-reset function with just a multimeter as it is just used in a transient manner. The IDE just pulses the DRT/RTS signals for just a short time, just long enough to trigger a reset to the AVR. A scope is really what is needed to see if this pulse is indeed being generated.

Lefty

6

@GregaG:

R4,R5= 100 ohm

You should not have RTS and DTR both trying to drive the Arduino reset circuitry. Current versions of Arduino/avrdude use DTR. What happens if you remove R4?

I mean, if you look at the Duemilanove schematic, the resistor in the RTS line has a value of "100_NM" I think the "NM" is Italian for "No Load" or "Do Not Install" or some such thing. My point is: It's not on the board.

Regards,

Dave

Footnote:
See, for example the Solarbotics FTDI Board. I have used this circuit with a number of Arduino Duemilanove-compatible homebrew boards (Ardweenies, too).

7

Ok got it working removed R4 and replaced R5 with a 100nF capacitator, just as in davekw7x Duemilanove schematic.
It seems arduino IDE puts DTR to ground and keeps it on ground till programing ends.
Actually i confirmed it by observing it with an osciloscope that i got back from the friend.

8

I am using the 5v FTDI cable from SparkFun with the Arduino Pro and can't seem to get things working. The FTDI is recognized on com 5, and when I jump tx/rx and send commands, they are repeated.

If I unplug the cable, the serial monitor can't find the device. Everything seems to be working fine, but something happens when I try to upload:

avrdude: Version 5.4-arduino, compiled on Oct 11 2007 at 19:12:32
         Copyright (c) 2000-2005 Brian Dean, (website)

         System wide configuration file is "C:\Program Files\Arduino\hardware/tools/avr/etc/avrdude.conf"

         Using Port            : \\.\COM5
         Using Programmer      : stk500v1
         Overriding Baud Rate  : 57600
avrdude: ser_open(): setting dtr
avrdude: Send: 0 [30]   [20] 
avrdude: Send: 0 [30]   [20] 
avrdude: Send: 0 [30]   [20] 
avrdude: Recv: 
avrdude: stk500_getsync(): not in sync: resp=0x00
avrdude: Send: Q [51]   [20] 
avrdude: Recv: 
avrdude: stk500_disable(): protocol error, expect=0x14, resp=0x51

avrdude done.  Thank you.

I eventually got things working by trying a combination of switching the cable around USB ports (the Dell I am working on has six ports) and plugging in an Xbee Explorer and a Duemilanov at the same time for a total of three FTDI FT232 chips connected.

9