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Telnet to GoPro Hero 3+ Black

The post is to explain how to log-in to the Linux console of Hero 3+ Black.

A real-time operating system (RTOS) is running on GoPros, and a Linux is also running as a task of the RTOS. For example, communication between Herobus and GoPro Hero 3+ Black is maintained by the RTOS and the web server (Cherokee), which GoPro apps on smart phones and/or Wi-Fi Remotes are to connect, is by the Linux.

There’s a well-known hack for telnet-ing to GoPros: Putting a tuned autoexec.ash file on the root directory of microSD card. But the hacks written for older GoPros don’t work for Hero 3+ Black. The issue is because Hero 3+ Black seems to lack some linux commands such as pkill or telnetd at a glance. But don’t worry. These commands are actually implemented by busybox, not by standalone binaries even for older GoPros.

Steps to telnet-ing to Hero 3+ Black

  1. Create a text file named autoexec.ash that contains the following lines:

    Note: Each end-of-line should be ‘\n’ (Unix style), not ‘\r\n’ (MSDOS style).
  2. Put the autoexec.ash file to the root directory of microSD card where DCIM and MISC reside.
  3. Insert the microSD into your Hero 3+ Black.
  4. Turn on Wi-Fi and enter “GoPro App mode” using the side button of camera body.
  5. Power on GoPro using the front button of camera body.
  6. Connect GoPro’s Wi-Fi from your PC or Mac.
  7. Wait about 30 seconds.
  8. Type telnet 8080 on your terminal.

Voilà! You can now enter to the Linux on GoPro Hero 3+ Black.
If you have memdump in the root directory of your microSD then you can dump RTOS log, too:

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How To Use MewPro and Its Application

We will show you how to use a first time MewPro. Basics to control GoPro camera will be explained. No external sensors involved (Maybe in following posts, we can show you some examples of sensor usages).


In order to use MewPro as a GoPro controller you need the following hardwares:

GoPro Hero 3+ Black
Neither previous editions nor Hero 3+ Silver work with MewPro. Hero 4 Black will be expectedly supported but we don’t promise this. (Update: Hero 4 Black/Silver are supported by MewPro 2/Cable. Please refer recent posts for them.)
SMD parts, Herobus connector and Arduino Pro Mini 3.3V 8MHz are soldered. If you want to use a higher performance microcontroller then Teensy 3.1 and GR-KURUMI are supported by the MewPro application.
Arduino Pro Mini Temporary FTDI Header
If you buy a MewPro from our shop the header is included in the package.
Sparkfun FTDI Basic Breakout – 3.3V and USB cable
Use 3.3V version of the breakout board. Any compatible board should work.

Remark: If you use Teensy 3.1 in the place of Arduino Pro Mini then you don’t need Temporary FTDI Header and/or Sparkfun FTDI board; and please consider to buy our Arduino Pro Mini / Teensy 3.1 Conversion Board.

Teensy Warning: If you use Teensy 3.1 with MewPro, please cut the PCB pattern between VUSB and VIN (On the a-lot-of-pad-side of Teensy board there is the special slit between pads to do so). Because MewPro uses RAW input from GoPro battery (about 3.8V). So if you connect VUSB (5V) to MewPro’s RAW then GoPro’s battery pin will become 5V. This will destroy your GoPro.


Arduino IDE 1.5.7 beta or newer
Older versions of Arduino IDE have bugs in Wire library that cause MewPro unusable.
MewPro Application
This is an open source software (MIT license). You can modify and distribute it as you like.

Remark: If you use Teensy 3.1 or GR-KURUMI, you must be a wizard or witch so maybe you know what is required a kind of softwares instead of above mentioned Arduino IDE.


Install Arduino IDE on your PC and launch it. In Arduino IDE [File]→[Open...]→ then open MewPro.ino.

Remark: MewPro.ino contains the following files as tabs; a_Queue.ino, b_TimeAlarms.ino, c_I2C.ino, d_BacpacCommands.ino, e_Shutter.ino, f_Switch.ino,g_IRremote.ino, h_LightSensor.ino, i_PIRsensor.ino, and j_VideoMotionDetect.ino. If you like to see what will be happen inside of your Arduino Pro Mini you could read any of them.

Connect MewPro to your PC w/ FTDI board and the temporary header.
Then connect them to GoPro Hero 3+ Black.

In Arduino IDE application, select [Tools]→[Board]→[Arduino Pro or Pro Mini], [Tools]→[Processor]→[ATmega328 (3.3V, 8MHz)], and [Tools]→[Port]→[(the port where you connected the FTDI cable)]. Then “Verify” the MewPro sketch and “Upload” it to Arduino Pro Mini board.

Remark: If you are using Teensy 3.1 c_I2C.ino will fail to compile. Just change the first four lines to
#if defined(__MK20DX256__) // Teensy 3.1
#include <i2c_t3.h> // *** please comment out this line if __MK20DX256__ is not defined ***
#else // Arduino Pro Mini
//#include <Wire.h> // *** please comment out this line if __MK20DX256__ is defined ***

Control GoPro

Open “Serial Monitor” in Arduino IDE window (click the the top right “magnifier” icon). Set [57600 baud] using the bottom right pulldown, [Newline] the middle pulldown, [Autoscroll] the left box checked.

Type ‘@‘ (one letter representing at sign) in the input area of Serial Monitor, and hit return key.

The message “camera power on” is shown and your GoPro Hero 3+ Black turned its power on.

The messages on “Serial Monitor” shows communication details between Arduino and GoPro. If this is the first time to connect your MewPro to GoPro then repeated erroneous “>01 08” is shown again and again. This is because the I²C EEPROM on the MewPro board is not properly initialized yet. So let’s type another one letter command ‘!’ (exclamation mark) in the input area of Serial Monitor, and hit return key.


Then other messages come from GoPro.
“role change” means that the role as a BacPac™ has been changed. This time the role is “master” (to understand the roles and modes of Dual Hero BacPac™ please refer our previous post).

In “master” role, we can’t push the shutter botton. But we can get composite video signal out of Herobus connector by using “VO1” command, which “master” MewPro automatically send to GoPro as shown in messages of above screenshot.

Next change the role to “slave”. To do this, type the one letter command ‘!’ again. The command ‘!’ toggles the role between “master” and “slave”.

You can see in the above screenshot various information is obtained from GoPro camera.

Now I²C EEPROM on your MewPro board is properly set to “slave” role. In the role we can push the shutter button of GoPro as usual. So we recommend using MewPro in this role.

Now we almost do every thing on GoPro from Arduino. Details of I²C commands are listed in our earlier post.

Try typing “SY1”. Then “SY0”. (Start recording! Stop recording!!)

If you finished type “PW0”. (This should power off your GoPro.)


Final Note: “SY1” command fails if the mode is different to the mode when GoPro is power on. That is if you change camera’s mode manually by using mode/power button of the camera body or “CM” (SET_CAMERA_MODE) command, then “SY” command will fail. This is due to GoPro firmware so please don’t blame MewPro. In order to workaround this restriction, use “DM” (SET_CAMERA_DEFAULT_MODE) command and set your camera to desired mode and “PW0” (power off). After this, try ‘@‘ (power on) and “SY1“.

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List of I²C Commands

Here is a list of I²C Commands among master/slave Bacpac™ of GoPro Dual System and GoPro Hero 3+ Black.

MewPro emulates not only the listed commands but also controls power supply of GoPro body (one letter ‘@’ command) and configures itself as master or slave (one letter ‘!’ command).

Examples: (Connect GoPro and MewPro and type a command followed by a return in your Arduino IDE Serial Monitor)

  • @ : power on (MewPro command)
  • PW0 : shutdown GoPro
  • TM0E0A0D090F00 : set GoPro clock to 2014-10-13 09:15:00 (hexadecimal of YYYY-MM-DD hh:mm:ss)
  • SY1 : shutter (camera mode) or start record (video mode)
  • SY0 : stop record (video mode)

Note: Some commands may not work as expected. It may depend on the role of BacPac™, master or slave. Try changing the MewPro role by entering ‘!’. This one letter command as well as power-on command ‘@’ are special built-in commands of MewPro and not listed in below.