Teensy 3.2 did not work with 3.3V coin cell?

[tranha]

Hi guys

I am having fun with my new Teensy 3.2 and currently learning the Real time clock feature on Teensy based on this link https://www.pjrc.com/teensy/td_libs_Time.html

I connected a 3V coin cell to VBAT and GND pins on teensy as instructed in the link (section TimeTeensy3). For some reason, I am curious about whether the coin cell works so I connected a DMM in series with teensy and the battery (as shown in the picture below) in order to measure the current flowing from battery to Teensy.



However, I did NOT see any current flowing (0 uA on the DMM). Then I bought a new Teensy (the second one) and did the same thing and this time the DMM read 1.4~1.5 uA . I am pretty sure my first Teensy is not broken, still working well. What happened to my first one?

P/S: For whole process, I did not connect my Teensy to any external source (aka USB cable to the laptop).

 

[Frank B]

I think, the black chip near to the VBAT Pinhole is a dual diode (refer Teensy 3.2 shematic).
Can you measure it ? (check if it is ok?)

 

[Epyon]

You must have a good DMM to measure µA accurately .

 

[tranha]

Can you explain a bit more specific like how I could check if it is ok ?

 

[tranha]

Yeh, it's my company's DMM, not mine haha

 

[defragster]

Have you put the crystal on either or both T_3.2's?

 

[tranha]

Have you put the crystal on either or both T_3.2's?

Yes I did

 

[tranha]

I think, the black chip near to the VBAT Pinhole is a dual diode (refer Teensy 3.2 shematic).
Can you measure it ? (check if it is ok?)

Can you explain a bit more specific ? like how can I measure it ?