Quote:
Originally Posted by DNSB
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.
|
It's annoying when stuff like that is wrong.
Also what did a certain European supermarket chain think they were doing with a red flash at the negative end and black band at the positive end of the battery. Why does the USA use white for neutral and black for mains on the live?
As non-rant aside:
LS-TTL (and maybe HCT) is compatible with 3.3V logic, as long as the supply is 5V, because logic "1" is about 2.7V. This is why 4000 series and 74HC series isn't compatible with original or LS TTL, and why there is an HCT series.
Indeed some UARTs work at 3.3V or 5V logic. The TTL serial port on Victron gear works at 3.3V or 5V, though the optional supply out (needed for a simple isolated serial interface) is 5V only.
I've used 74LS TTL to interface to a 3.3V JTAG connector.