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Author Topic: Sketch upload fails, FTDI chip constantly TX'ing  (Read 483 times)
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Hello everyone, this might be a little convoluted but I'll try to keep it short.

I have an SB Freeduino (v2.3), and two months ago I unknowingly shorted its 5V pin to its ground in a circuit. I did the same with another friend's Arduino, realized my mistake and rewired, and afterwards her's worked. I can't remember if my own worked right after I fixed the circuit (kind of hid it in a box and ran away), but for sake of discussion I'll assume it wasn't completely destroyed. Both programmed fine before the shorting.

Since then I've recently migrated to a new computer, connected it for the first time, installed the FTDI drivers for virtual COM ports, and it looks like Windows 7 can at least see the FTDI. I've also done tested the same on another W7 computer with identical results. It shows up in both "Ports (COM and LPT)" as a "USB Serial Port (COM#)" and "USB Controllers" as a "USB Serial Converter".

When I power it on or connect it to a computer, the power LED and blue LED on pin 13 both work (#13 flashes), TX comes on and flashes for a bit, then it seems stable. But whenever I try to upload a sketch (eg. Blinky), it freezes near the end, and TX is constantly on.

Even outside of uploading a sketch, if I try to monitor the connection via Serial Monitor from the IDE, I get an endless stream of "!!!!!!((((!(!(  !!!((!(" which may be repeating sequences or assorted "!"s and "("s. I tried using PuTTY and it also gave me a stream of "!!!!!!!!        " (they're actually longer than that) seemingly repeating lines. The baud rate is set to be 9600 (or whatever the default is).

I tried the loopback test by jumpering digital pins 0 and 1 (TX and RX), went into Serial Monitor, typed stuff, which SM then spat back out at me. So it seems the FTDI isn't damaged.

Is there a problem with the bootloader (it uses the optiboot one)? Should I try burning another one to the chip off a friend's Arduino R3?



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The bootloader would be my guess.  Just hook up things like this and upload the sketch:

Serial monitor communications are 115200.

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