One of the exciting new features of XJLink2 is the ability to measure a number of voltages. Via the 20-way XJlink2 connector you can measure up to 18 different voltages. This means supply rail voltages can be measured before (and during) JTAG testing, and analogue measurements are now simple to make during your tests.
Many modern boards have a number of supply rails. Some of these need to be quite accurate to ensure stable operation. The XJLink2 is +/-( 0.2% + 10 mV) accurate, which is easily good enough to test supplies that have to be within 1% tolerance – we find most supplies have to be within 5%.
The input voltage range of the XJlink2 is 0 to 5 V. If you have a higher voltage rail then, then a potential divider will be required.
To use the voltage measurement you simply have to make sure the voltages / supply rails you would like to measure are brought out to spare pins on the XJLink2 connector.
You can take this a step further, If you what to check the current though an LED this becomes easy with XJLink2. Most LEDs have a series resistor to limit the current. If this resistor is between ground and the LED, you just need to measure the voltage across the resistor and do a little bit of maths with the resistor value to calculate the current in the LED ( V=IR ). If the LED takes the correct current then it is very likely to be working. LEDs not fitted / fitted the wrong way round / open circuit or short circuit will almost always give very different reading from the correct value. This might enable you to test the LED without asking the test operator if the LED lights.
This an example of how XJTAG can save you time and reduce the amount of test equipment you need during production testing and board bring up.