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10 years, 1 month ago.
FRDM KL46Z light sensor : J8 jumper
From the file "FRDM-KL46Z_SCH.pdf" page 5, what is the function of J8 in the VISIBLE LIGHT SENSOR BLOCK ?
My understanding is that the voltage from light sensor can be read from Pin TPE22 when there is a jumper at J8( close ) . However, using DVM, I can obtain voltage from PIN PTE22 (fig 7 in FRDM-KL46ZUM.pdf) without doing anything to the J8 ie. the J8 is open.
From PTE22, I feed the connector to one of the Analog pin ( A0-A5), and do the AnalogRead() and I got the value. All of these without touching anything on the J8 ( mine is not populated )
Can someone shed some light on the function of J8 jumper pin ?
Thanks.
1 Answer
10 years, 1 month ago.
If you check the bottom you should see under J8 a PCB trace. By default it is a short. It should have been mentioned in the schematic, but by default (almost) all jumpers on the Kinetis boards are shorts. You can cut the PCB trace (small screwdriver for example), and then if you put on a jumper you can re-enable it.
Aftere reading your answer, I unscrewed my board from the base and saw that on the bottom surface, several jumpers are indeed connected.
Going back to the schematic, the jumper with pink color indicates connection ( short ). Jumper with just white color within its frame is not connected ( open ) such as J7 which comes populated with jumper on.
Thanks for the help.
posted by 22 Mar 2014