a Virtual Robotix Network Team

[HOW TO] Connect SD card on VRB 4.5 for full nutt-x operations

After the latest firmware release, vrb supports RtOS for operation.

A neat feature is the advanced and quasi-unlimited logging capabilities. The logs will be written after each flight session and they are stored on SdCard.

on Vrb 5.0 the microsd adapter is on board, but for owners (like me) of the previous hw revision, we need to work creatively.

the standard SD-CARDs is accesible via SPI bus, and the mandatory connections are : MISO(master-in-slave-out) / MOSI (master-out-slave-in) / SCK (clock) / SS (signal-select) / GND and VCC+.

all of them is available on JP27  connector (the white one near the INPUT rails). This one, has 8 pin connections, we need (as stated before) only six of them.

We can figure out which ones by looking at image below.

pin-1 is the one which is more close to MCU (the big chip on the center of the board); pin-8 is the one near the input rails.

I could buy a specific adapter for sd card, but I decided to be creative and I invented this system, which at the moment seems to work very well.

Basically I used a simple adapter sdcard-> microsd and I soldered directly to the exposed pad on the back as shown.

all the connections are straight point-to-point. watch out for "exp_EN" which connects to SS on sd card adapter. i've ordered pre-crimped cables and the female terminal directly at VirtualRobotix.

You can check if everything works correctly by connecting the VRB with sd-card inserted in Mission planner and connect with Terminal. Once connected, enter in "TEST" and then in "SHELL".

Check for a folder called "APM" into fs/microsd path.

No more configuration is necessary.

Now the system will log all the flight data on different files on sd, and you can retrive them by simply unplugging the card from the copter and reading it with a computer.


NOT all microSD is +5v tolerant on vcc. so i've tested a solution using a 78l33 linear regulator soldered directly on pads.

the "VCC_5V" connection goes in the In pin of the 78l33 (pin3), gnd on sdcard pad 3 and the output of the 78l33 goes to pad 4.

The mod works flawlessly.

check datasheet of 78l33 for pinout numbering.

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Comment by Monroe Lee King Jr. on September 13, 2014 at 12:08am

Hey this is great!

Comment by Michele Branchini on September 12, 2014 at 7:59pm

you are absolutely right. i've just figured out a way to integrate a 3.3voltage regulator directly on tha sd card adapter

i'll modify the blog post with all the photos as soon as possible

Comment by Marc LE BRET on September 12, 2014 at 6:02pm

I had some concern with the 3,3v needed for SD Card and the 5v output from the plug. As I had some problems with the logs on the SD Card, I moved the VCC in to the 3.3v from the GPS plug.

With a new card, logging is now fine,


Comment by Marc LE BRET on September 10, 2014 at 11:06am

Done, it works,



Comment by emile on September 10, 2014 at 8:10am

Thanks for sharing. Very creative and useful!


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