VR μBrain

This is a first draft, so please report incorrect information.

Virtual Robotix’s MicroBrain is the smallest 32bit Autopilot released by VirtualRobotix.

It’s main characteristics are:

• 168Mhz ARM CortexM4F micro controller with DSP and hardware fpu.
• 1024KiB flash, 192KiB of RAM.
• Accelerometer, MEMS gyroscope and barometer.
• 8 RC standard input PPM, PPMSUM, SBUS.
• 8 RC output at 490 hz.
• 1 SD Card Slot until 64 gigabyte.
• 1 I²C Bus.
• 3 serial porti:1 for option GPS 1 for SBUS 1 telemetry.
• 3 digital switch (ULN2003) 2 LED 1 BUZZER.
• Jtag port for realtime debug.
• 1 Input analog lipo voltage control.
• Dimension 3.8×3.8 cm 10 gr hole distance 3.2 x 3.2 cm.
• GPS and Magnetometer as option.

Drivers download

Follow this link to download Windows drivers.

Once downloaded, double click on the .exe to unzip.

Choose a folder where you want to save them and once unzipped, go to unzipped folder VRuBrain_drivers_2.0.0.5 and run either DPInstx86.exe for 32bit Windows or DPInstx64.exe for 64bit windows.

Board layout

VR μBrain 5.1

You can also connect telemetry using this pins: (be careful that you need to get the 5V from another pin header).

VR μBrain 5.2

VR μBrain 5.2 have the same hardware of 5.1 but with different management. The main difference is about the two connectors “ESC SERVO” and “RC RADIO”. With this new configuration this two connectors are switched.

• OUT: Looking at the connector from the front, from left to right, the pinout is:
  1. 5V
  2. GND
  3. PWM OUT 1
  4. PWM OUT 2
  5. PWM OUT 3
  6. PWM OUT 4
  7. PWM OUT 5
  8. PWM OUT 6
  9. PWM OUT 7
  10. PWM OUT 8
• IN: Looking at the connector from the front, from left to right, the pinout is:
  1. 5V
  2. GND
  3. ANALOG INPUT 1 (defined as default for IBAT – pin reference for APM Parameters is 1)
  4. ANALOG INPUT 2 (pin reference for APM Parameters is 2)
  5. ANALOG INPUT 3 (pin reference for APM Parameters is 3)
  6. PWM OUT 9
  7. PWM OUT 10
  8. PWM OUT 11
  9. DIGITAL SWITCH (pin reference for APM Parameters is 33)
  10. PPMSUM

Pre requisite:

5 Volt BEC to connect on +5v – gnd near GPS – LED 1-2.

GPS + Magnetometer compatible with 3DR – VRX DF13 connector.

Micro Usb cable.

About Micro USB connector keep atention it is fragile connect and disconnect the connector using finger on it , Do not pull or tug the usb power cord. here:

https://vrbrain.wordpress.com/process-of-hardening-a-usb-connector-for-the-card-vr-micro-brain-5-1/

you find some info about mechanical update of USB connector to remove the iusse. If you prefer you can send the board to lab for update it for more info and for check if your board is affect by the iusse contact info@virtualrobotix.com. Only early batch of production have this iusse in new production we yet update it before to ship.

 

Powering the board

The board should be powered by the +5V and GND on the pin header next to the micro SD Card port near Led1 and Led2.

It is also possible, but not advised to power up with an esc on the output connector.

Here is an example showing the recommended option; connecting the 5V output of a ubec to the led and buzzer pin header:

Connecting the receiver

To connect the receiver you have three options:

1. Connect futaba SBUS (or Taranis) to the appropriate 3 pin connector.
2. Connect PPMSUM on the 7th INPUT channel.
   Beware that upgrading from 3.2 to 3.2.1(beta) PPMSUM input has moved to PIN7. This will allow us to use the first 4 inputs as optional outputs (CH9 to CH12).
3. Connect all 8 inputs using the the connector provided.

Note.

 

Please note that at the moment you either have a firmware that supports PPMSUM and SBUS or PWM.

 

At the moment of writing there is no way you can have the firmware for PWM and PPMSUM at the same time.

Here is an exemple to show how we connect the Fr-sky x8r receiver to the VR Micro Brain:

Connecting the ESCS

Please do not power the VRμBRAIN with this connector. These cables a re slightly too small for current consumption with all equipment attached.

This is how to connect the ESC to the provided cable using a male-to-male pin header. Please note we connect only the WHITE wires from the esc:

If you are using OPTO ESCS (like DJI or any other true OPTO isolated ESCS) you need to connect also the GND to any GND on the VRμBRAIN.

This is an example on how to do this:

 

 

Connecting the GPS and External magnetomenter.

If you have bought our GPS with integrated magnetometer, you will have two connectors on the edge of the board to connect them.

The GPS is on the upper face, and the magnetometer on the lower face.

The connectors are compatible also with 3DR GPS + Mag

First connection of the board:

Download Windows drivers: Drivers download page

Open the file you’ve just downloaded, and then run the installer:

DPInstx64 for 64 bit operating systems.

Or DPInstx86 for 32bit operating systems.

Before using the board, you need to install the Mission planner software available here (permanent link to latest):

http://ardupilot.com/wp-content/plugins/download-monitor/download.php?id=82

Once downloaded, please install it by double-clicking on the .msi file.

Once done, your board should be recognized as a com port, with name VR Micro Brain

(please note: port COM is 13 on my computer, it could be different on yours!)
Open mission planner;

We now need to upload the firmware on the board (only the first time):

To do this, check the com port is correct, and baudrate is 115200

DON’T CLICK ON CONNECT!!
Then go to “Initial setup”:

“Install firmware”:

And select the firmware according to your set up (+ or x configuration will be defined later):

Wait for the firmware to install, and click ok if asked.

Once done, you can now click connect, and set up your board (radio cal, etc) using the setup and tuning page. Next time, you’ll just have to click connect and access setup.

 

Advanced users:

– Uploading the bootloader:

You can upload the bootloader by two different ways:

1) Using the micro Sd card (only on last firmware, you must have fw uploaded on board)

Select the right bootloader in this folder (after downloading it)
https://github.com/virtualrobotix/VRX_binary/archive/master.zip
save the .bin file on the sd card with name “bootloader.bin”
put the sd cart back on the board, and plug it in. The firmware should now update the bootloader, and then delete the file on the sd card.

2) Using the DFuse software

– Take off the jumper on the board.
– Connect the USB cable. The led should blink blue.
– Open the DFuse software.
– Select the right bootloader file (in the downloaded file above, at this link:)
https://github.com/virtualrobotix/VRX_binary/archive/master.zip
– Then click “upload”. This should go very fast (about 2-3sec)

Once done, disconnect the usb cable, put the jumper back on and reconnect the USB cable. You can now use the Mission planner procedure (see top) to upload firmware.
– Uploading the firmware + bootloader

You can also upload both the firmware + the bootloader in one time with dfuse. To do that, use the above procedure, but choose the appropriate DFU of the firmware section in the folder previously downloaded.

 

FAQ

Is it possible to upload the firmware with mission planner ? 

Yes it’s possible update the firmware with mission planner… you need only usb cable, then you can use standard function on mission planner for update firmware on uBrain and change frame configuration.

Is it possible to use usb to power up the board and for telemetry connection.

Yes is possible but keep attention when you connect and disconnect the micro usb connector because it’s fragile respect of mini usb available on other VR Products as VR Brain 4 and 5

Is it possible to use standard PWM with VR uBrain 5 ?

Yes it’s possible. Follow this link and then navigate in Copter for multirotors or Plane for planes, select Custom–>Stable->PPM->Your Frame and then download the right firmware for your board.

Firmware for VRμBRAIn are called Arducopter-vrubrain-v51P.vrx