# OpenLog

**URL:** <https://community.sparkfun.com/t/openlog/41461>\
**Category:** Tools\
**Created:** [February 4, 2021, 7:22pm UTC](https://community.sparkfun.com/t/openlog/41461 "2021-02-04T19:22:23Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![Bruce\_One](https://avatars.discourse-cdn.com/v4/letter/b/76d3ee/32.png) [@Bruce\_One](https://community.sparkfun.com/u/Bruce_One)\
**Post date:** [February 4, 2021, 7:22pm UTC](https://community.sparkfun.com/t/openlog/41461/1 "2021-02-04T19:22:23Z")

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I have 2 Sparkfun OpenLog units both of which act the same way. They are connected to GPSs through the UART connection, 5 Volts. One uses a Sparkfun NEO-M9N and the other is connected to an M8N. The baud rate is set correctly in the config file on the SD card.

On startup one of 4 things happens, seemingly each about 25% of the time.

1. The logger records a blank file

2. It records a file that starts with “`˜`ø˜`fffà† ˜à† ˜à† xà†ff†žþž€˜”

3. It records a file that starts with “顠悘晦†蘘頀ᣠ†砘蛠晦ᢆ鸆黾ڀ˜惦頀ᢞ”

4. It records a file with the correct NMEA text output.

What can I do to help the situation?

Thanks!

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<div class="post-metadata">

**Author:** ![jremington](https://yyz1.discourse-cdn.com/sparkfun/user_avatar/community.sparkfun.com/jremington/32/6595_2.png) [@jremington](https://community.sparkfun.com/u/jremington)\
**Post date:** [February 5, 2021, 1:01am UTC](https://community.sparkfun.com/t/openlog/41461/2 "2021-02-05T01:01:41Z")

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The OpenLog is a 3.3V device, and the inputs **must not** be exposed to 5V. You need a level shifter of some sort between a 5V TX output and the 3.3V RX input. A 4.7K series resistor works, and is probably safe.