Quote:
Originally Posted by Renate
The good UARTs use an FTDI232R chip which can use an external voltage for the logic level shifters.
There is the 5V already on USB Vbus, the chip has an internal 3.3V regulator and PCB manufacturers add a 1.8V, 2.5V and sometimes a redundant 3.3V regulator.
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The problem was the screened print that said showed J1 5V, J2 3.3V, J3 2.5V, J2 & J3 1.8V (I don't have the board in front of me so I think that was the pattern). Unfortunately, J1-J3 were reversed. He was lucky in that his original project used 3.3V so J2 was correct. His next project was supposed to use 1.8V so J2 & J3. Luckily J1 & J2 was invalid and set the output to < 1.0 V so no damage was done but no communication could happen. It took a while to figure out just what was going.