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I have a USB serial device from Sparkfun.

https://www.sparkfun.com/products/15096

Unfortunately, I need access to the RTS pin (to, connect to an ESP8266) but this module does not pin it out. I have found and manually tested the correct pin on the chip itself. Is it possible to solder a jumper directly to the chip's pin, and use that? Are there good tutorials on this? Googling didn't reveal anything relevant.

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    \$\begingroup\$ why would you think that it is not possible? ... you could remove the 6-pin header connector and solder on a 7-pin or an 8-pin connector, then run a thin, insulated wire to pin 14 of the CH340C .... you could drill a small hole in the board and pass the wire from front of the board to back just to make the wire more secure \$\endgroup\$
    – jsotola
    Commented Mar 2, 2020 at 0:07
  • \$\begingroup\$ I guess I'm worried about messing up the existing solder connections on the module. I've only ever done hole-through soldering. \$\endgroup\$
    – Jonah
    Commented Mar 2, 2020 at 0:43
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    \$\begingroup\$ you could also use a "flying lead" ... drill a small hole through the middle of p in Sparkfun ... use jumper with a female connector like a dupont jumper ... pass the wire through the hole and solder it to the IC pin .... you may have to use a thin solid wire to go from the IC to the jumper wire .... glue the female end of the jumper to the side of the 6-pin header to make it a 7-pin header \$\endgroup\$
    – jsotola
    Commented Mar 2, 2020 at 0:49
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    \$\begingroup\$ What jsotola said. You can use hot glue to strain relieve the wire. Don't cover any solder joint with hot glue, just the insulated part of the wire. If you ever have to remove the hot glue, use rubbing alcohol (isopropyl alcohol). Ideal way is to strip and tin the wire, then add flux to the IC pin. Add a little extra solder to the pin (but not so much that it bridges to the next pin). Hold the wire with tweezers. Melt the solder with the iron, place wire inside the molten solder blob, hold it long enough for the wire to heat up, then remove iron and hold wire still until the solder hardens. \$\endgroup\$
    – user57037
    Commented Mar 2, 2020 at 0:58
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    \$\begingroup\$ Eventually, if nobody actually answers this question, just post a picture of what you did and accept that as the answer. It is OK to answer your own questions and accept your own answer if it is the best answer in your judgement. \$\endgroup\$
    – user57037
    Commented Mar 2, 2020 at 1:00

1 Answer 1

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Yes I have done this many times just be mindful of static charges and make sure no power is applied to any of the circuit. It will work.

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