I use the Data Logger Shield to read out a TMP36. As suggested in http://learn.adafruit.com/adafruit-data ... ger-use-it, I took the 3.3 V from the shield. It gave me very erratic and instable temperature readings. Then I used the Arduino Uno's 3.3 V, and the readings were perfectly fine.
Without an SD card inserted, I measure 3.284 V, which is I guess all right (tough 5.3% below 3.3).
As soon as I insert an old 32 MB SD card, it fluctuates between 4.00 and 4.07 V.
Is this expected behaviour? That is, not to use the shield's 3.3V when a SD card is inserted?
I tested with an external 12 V adapter, and powered by USB, no difference. Also tested with 2 GB micro SD card, same results.
Data Logger Shield 3.3-4.0 V [SOLVED]
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Data Logger Shield 3.3-4.0 V [SOLVED]
Last edited by markruys on Mon Apr 15, 2013 2:11 pm, edited 1 time in total.
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Re: Data Logger Shield 3.3V
Definitely not expected behavior.
Is your sketch reading or writing the SD card?Without an SD card inserted, I measure 3.284 V, which is I guess all right (tough 5.3% below 3.3).
As soon as I insert an old 32 MB SD card, it fluctuates between 4.00 and 4.07 V.
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Re: Data Logger Shield 3.3-4.0 V [SOLVED]
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The problem was that I wired an LCD display to pins 11 and 12. This interferes with the SD card which needs these pins for the SPI interface.
The problem was that I wired an LCD display to pins 11 and 12. This interferes with the SD card which needs these pins for the SPI interface.
Please be positive and constructive with your questions and comments.