I've just bought a cheap FT232RL USB To serial adapter (EAN: 0680004529143). It does not come with a manual and the short description simply mention:

  • USB power supply, can choose 5V or 3.3V ,set by jumper.

However starring at it I cannot see anything that would looks like a jumper. Here is the view from the top: enter image description here

And here is the view from the bottom: enter image description here

Anyone has a schematic of what needs to be done, and where is this 'jumper' ?

  • 2
    \$\begingroup\$ My guess (and it is a guess) is that it's those 3 pads in the middle on the back. It is set to 5V IO voltage as standard, for 3.3V cut the trace between the middle pad and the bottom pad and then link the top and middle ones together. USB will always be 5V power with 3.3V signaling, this is for setting the voltage on the digital IO lines. \$\endgroup\$ – Andrew Jun 1 '17 at 10:36
  • \$\begingroup\$ Cut the trace is not exactly my definition of jumper...oh well \$\endgroup\$ – malat Jun 1 '17 at 10:45
  • \$\begingroup\$ I agree with @Andrew, those three pads at the middle on the back. Looks like it's set to 5V by default (note the track connecting the middle pad to the 5V pad) though a quick test with a multi meter would let you know. \$\endgroup\$ – Puffafish Jun 1 '17 at 10:45
  • \$\begingroup\$ Any link for where you purchased it? \$\endgroup\$ – StainlessSteelRat Jun 1 '17 at 11:23
  • \$\begingroup\$ If I type the EAN above in google, it shows the link directly...hint: amazon \$\endgroup\$ – malat Jun 1 '17 at 11:25

USB to TTL Adapter Based on FT232RL

Slightly different board but this page confirms the comments. FT232RL

+3.3V and +5.0V signal Level Support using SMD jumper.

Voltage Level on RXD, TXD pins: 5.0V (Default), 3.3V through smd solder type jumper.

5V Jumper is hardwired by default. Cut trace with knife and solder wire to 3.3V tab.


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