2.The voltage tolerance measuring apparatus as claimed in claim 1, wherein the switch circuit includes a first DC power supply, a second DC power supply, a first resistor, a second resistor, a first transistor, a second transistor, a third transistor, and a fourth transistor, the gate of ...
One of those is driven by PIO0_7 and it's tied to +5V with a 1.3k resistor. Once PIO0_7 switches low the LED is on - OK.Now comes the interesting part: How can I switch this LED off? Open-drain would be the way to go, right?The LPC81XM data sheet states the following ...