Figure 7 shows the digital outputs of the microcontroller that connect to a DAC circuit (AD420) with 16-bit CMOS current output using the SPI protocol. With this circuit, the device acquires a current ...

While useful for testing wiring and making sure connections are solid, they typically only test using DC. ... up to the point that they become open and short circuits respectively.

The voltage at point A changes from a few hundred millivolts during short circuit to 4.7 V during normal operation, providing a clear indication to the CPU’s input port.