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How To Use MewPro Bastet

In this post we explain how to connect wires to MewPro Bastet.

MewPro Bastet Pinout

The following picture shows the pinout of Bastet.

There are pins for master, slave(s), and programming (FTDI Breakout Board) denoted by color brown or red, green, and blue, respectively.

Software For Master MewPro 2 board

The MewPro 2 board (MewPro #0 in this diagram) attached to the master camera (GoPro #0) must have MewPro 4 master firmware installed.

To install the master firmware please follow the ordinary steps described in this post with changing the following two lines in the MewPro4 source code MewPro.h at lines 6 and 9 from:

boolean debug = true;


boolean debug = false;

respectively, before compiling and uploading to the board.

Note1: Slave MewPro 2’s should have the default firmware without any modification to the MewPro4 source code.

Note2: If you like to use Bastet in the good old housing that came with GoPro’s discontinued Dual Hero system for Hero 3+ Black then it’s better to modify the 17th line in `MewPro.h` as `#define DUAL_HERO_ORIENTATION`. Uploading this to slave MewPro board(s) will enable the slave camera to be upside down regardless of master’s orientation setting.*

Connect To Master

Firstly, serial line, GND, and sync signals must be connected as follows:

GND and sync signals
signal name MewPro 2 (master) Bastet
Serial TXO RXI

Next, there are three cases to feed power to the master camera:

  1. Master camera is powered by internal battery.
  2. Master camera is without internal battery and powered by external 5V at the herobus connector.
  3. Master camera is without internal battery and powered by external 5V at the side USB connector.

[Case 1: Master camera is powered by internal battery]

The pins for master are aligned with those of MewPro 2 board. So you can put Bastet on top of MewPro 2 using lead frames or tin plated wires as in the following photos. (If you purchase Bastet from our shop then these lead frames are included.)

Bastet and lead frames
Lead frames soldered

The above is our recommended way of connecting to the master. However, there might be cases that there are no room for Bastet board on top of MewPro 2 in your rig or cases of using MewPro Cable as a master. If your situation dosn’t allow placing Bastet on top of MewPro 2 board then please refer the following table and image.

Master camera is powered by the internal battery
voltage rail MewPro 2 (master) Bastet
powered by internal battery internal battery
unregulated 3V8 PWRSTBY PWR STBY
3V3 not connected not connected (*)
5V not connected not connected

Note *: Bastet outputs regulated 3V3 for slave MewPros.

Camera is powered by the internal battery

[Case 2: Master camera is without internal battery and powered by external 5V at the herobus connector]

If you like to power the master camera through the herobus connector please refer the following table and image.

Master camera is without internal battery and is fed through the herobus connector
voltage rail MewPro 2 (master) Bastet
powered by Bastet external 5V
unregulated 3V8 not connected DON’T CONNECT TWO PWRSTBY PINS! not connected
3V3 VCC 3V3

Note **: Never connect 5V to MewPro 2’s PWRSTBY. To do so will instantly ruin your camera.

[Case 3: Master camera is without internal battery and powered by external 5V at the side USB connector]

If you like to power the master camera through the side USB connector please refer the following table and image.

Master camera is without internal battery and is fed through the side USB connector
voltage rail MewPro 2 (master) Bastet
powered by Bastet external 5V
unregulated 3V8 not connected DON’T CONNECT TWO PWRSTBY PINS! not connected
3V3 VCC 3V3
5V not connected PWR STBY (**)

Note **: Never connect 5V to MewPro 2’s PWRSTBY. To do so will instantly ruin your camera.

Connect To Slaves

Connections between Bastet and slave MewPro 2’s are the same to those between Iliad and MewPro 2’s (Note: In Iliad system all MewPro 2’s are slaves). You can use our Stackable Hub with Buffer or simply connect thru holes by wire or make something like a DIY octopus cable to connect Bastet and slaves.

Moreover, Bastet’s thru holes for 6-core cable to slaves are aligned as the same to Iliad.

Thus, please refer the Connection section of our blog post How To Use MewPro Iliad about wiring for slaves.

Tips For Reliable Use

a) It is necessary to push buttons of master camera SLOWLY. If there is not enough period between two button presses then the master camera fails to notify some events to Bastet through master MewPro 2 board. This is GoPro’s firmware limitation so don’t blame MewPro and Bastet. The failure can be resulted in video/photo mode inconsistency among cameras and, moreover, incompatible sync signals can make cameras freeze. And also, please WAIT 8 SECONDS AFTER POWER ON because camera booting up takes this long.

b) Camera’s “low light” option is not usable with external sync. Thus, it is set to off by MewPro 2’s default, however, you can also accidentally enable the option. So always take care camera’s LCD is not showing you the “low light” icon.

c) After assembling/connecting Bastet, MewPros, and cameras it is normal that the system becomes unstable. In order to overcome this situation Bastet resets all the MewPro 2 boards every time when it receives power off command from the master.

This behavior enables us to reset the whole system by following the steps below:

Reset Procedure of Bastet System

  • [Step 1: Slave OFF] By long pressing the camera’s mode button, power off each slave camera if it is on. (Even when some cameras are frozen, pressing its mode button for six seconds makes it power off.)
  • [Step 2: Master OFF] Master camera’s power must be off at last.
  • [Step 3: Master ON] After all the cameras are power off, power on the master camera by using its mode button or wifi RC. To do this also power on all the other cameras.
  • [Step 4] If something strange happens then go to Step 1.

How To Update MewPro Bastet Software

Please refer this post.

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Introduction To MewPro Bastet

MewPro Bastet is a small device that enables us to control/genlock GoPro Hero 4 cameras. Unlike our monolithic MewPro Iliad, it simply listens broadcast by the master and provides sync signals for all of cameras while recording.

MewPro Bastet is ready to purchase in our shop, however, its product description is still under construction (I’m now editing it…).


The following video shows the three Hero 4s are synced and controled by Wi-Fi RC. (Power on — change mode -(video)- start recording — stop -(photo)- take a photo — power off.)

To make the footage we used:

  • 3 GoPro Hero 4 Black (one master and two slaves)
  • 3 MewPro 2
  • 1 MewPro Bastet
  • (cables and plugs/receptacles)

The white PCB is Bastet, the blue PCBs are MewPro 2s.

In the photo above you’ll also find bulky RJ45 Ethernet receptacles or “Stackable Hub with Buffer”, however, these parts are not always necessary for syncing cameras in, for example, weight restricted environments such as shooting videos from the sky.

How It Works

In Fig. 1 the number of GoPro Hero 4 cameras is five for example. Of course, any number of cameras can be synced in this way.

MewPro Bastet is put between the master camera (GoPro #0 in Fig. 1) and the slaves (GoPro #1, #2, #3, #4 in Fig. 1). It wiretaps the command packets that the master sends to the slaves. It understands all commands and changes its internal states accordingly. And once master’s shutter button is depressed then it begins to generate sync signals (VSYNC/HSYNC).

Fig. 1

In the diagram above “Hub (optional)” can be either solder joints of wires or our Stackable Hub with Buffer or some kind of DIY octopus cable or a strip board with 6 lines in parallel or something. We only offer a solution with Stackable Hub with Buffer but you can do it yourself in place of this in order to reduce the space.

Comparison Table Between Iliad and Bastet

For your information the following is a brief comparison table between Iliad and Bastet.

Iliad Bastet
Size larger than Hero 4 equal to MewPro 2
MCU ATmega2560 ATmega328PB
LCD 16 x 2 none
Switches 3 0
Infra Red 1 0
Wi-Fi no master camera (*)
Software MewPro_Iliad MewPro_Iliad
MewPro 2 all slave all slave but one master (**)

Note *: All the cameras are controlled by the master regardless of whether the change is made by using Wi-Fi or master camera’s button press.

Note **: The MewPro 2 board attached to the master GoPro must have MewPro 4 firmware that is compiled with #define BASTET_MASTER compiler directive. While other boards should have the default MewPro 4 firmware.

How To Use MewPro Bastet

In the next blog post we’ll explain how to connect wires between Bastet and each MewPro boards.

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How To Use MewPro Iliad

MewPro Iliad generates HSYNC/VSYNC and synchronizes any number of GoPro Hero 4 Blacks or Silvers. The post describes details of this new genlock device.

How Iliad Works

The following clip is a demo of MewPro Iliad, the production version of our sync generator/controller for Hero 4 Black/Silver.

Iliad can be interacted with any IR remote by learning its code and/or with three on-board momentary switches, which correspond to the familiar Mode/Shutter/Setting buttons of GoPro Hero 4 Blacks. In the short footage above three cameras are in complete sync: Power on – sync setting – change video resolution/protune on – start recording – stop recording – change to camera mode – shoot photo – power off.

To make the demo we used the following items:

GoPro Hero 4 Black n
MewPro 2 * n
MewPro Iliad * 1
RJ45 Stackable Hub with Buffer * for input: 1, for output: n
USB wall charger 1
Cables and wires

(Note: n is the number of cameras. In our case n=3.)

The items marked * are in our shop.

Currently MewPro Iliad is still in beta stage, however, here we venture to sell it because there is huge urgent demand. It can do the following.

  • Video: All the video modes Hero 4 Black/Silver supports
  • Photo: Single shot in any resolutions

The camera has many charming submodes such as “Timelapse” or “Night Lapse” or “Burst” or something but shooting in these submodes is not genlocked. This might be due to camera’s restrictions so please don’t blame MewPro and Iliad.

GoPro Hero 4 Black/Silver’s firmware can be version 03.00.00 or later (N.B. The version is shown on camera’s LCD without the last two digits as “03.00” at camera power on).

Note: There is a fatal bug in version 04.00.00 or later that causes bulk setting sync transfer impossible, i.e., settings cannot be synced when power on. Thus, we strongly recommend to use MewPro Iliad with the firmware version 03.00.00. And if you have version 26.01.10 for Omni then it also works after sending a command to MewPro board, however, in this case only two video modes (2.7K 4:3 30/25 and 1440 4:3 60/50 (NTSC/PAL)) are supported and there is no reliability improvement at all.


MewPro Iliad and MewPro2’s can be connected by using 6-core cables or (straight) ethernet cables of any category.

Case 1: Using 6-core cables

On the Iliad board there are thru holes for necessary signals.


Connect 5 signals and optional 1 line to each MewPro 2 board as follows:

Table 1. Connection Between Iliad and MewPro 2
Iliad MewPro 2
TRIG (no connection)
TXO RXI (**)
3V3 VCC optional (***)

Remark *: There are two GND pins on the Iliad board. It doesn’t matter you connect both or either of them.

Remark **: On MewPro 2 board there are two different RXI pins “FTDI RXI” and “RXI 1”. The former pin at the row “FTDI” is ONLY FOR PROGRAMMING. So you should connect the serial line from Iliad/Bastet to the “RXI 1” pin at the edge.

Remark ***: If you like to use Hero 4 camera without battery and feed 5V power thru side USB socket or VUSB pin on MewPro 2 board then also connect this line in order to feed power to MewPro 2 board from Iliad.

Case 2: Using ethernet cables

The Iliad board has a RJ45 receptacle to connect to an ethernet cable of any category. You can directly connect this to one or more MewPro 2 boards by simply branching each of signals.

Signals at the RJ45 receptacle of the Iliad board are:

Table 2. Signals at the Ethernet Jack

pin # T-568A color T-568B color signal
1 white/green white/orange (no connection)
2 green orange VSYNC
3 white/orange white/green (no connection. reserved for TRIG)
4 blue blue HSYNC
5 white/blue white/blue GND
6 orange green RESET
7 white/brown white/brown TXO (Iliad) / RXI (MewPro 2)
8 brown brown 3V3

If you also bought RJ45 Stackable Hub with Buffer from our shop then all RJ45 connector pins are aligned as in Table 2.


The software is being developed by using Arduino IDE that is downloadable from If you are not familiar with Arduino platform there are many introductions or tutorials on the Net. So please refer them first.

If you bought Iliad from our shop then all the software is pre-installed. However, there will be frequent updates or bug fixes from us you’d better prepare the IDE.

Software for MewPro 2

Source code for Hero 4 Black/Silver is downloadable as a zip file from here:

To compile/upload please refer the included in the zip file.

Software for MewPro Iliad

The Iliad board is designed as a shield of Seeed Studio’s Seeeduino Mega, which is an Arduino Mega 2560’s enhanced clone. You can use the Iliad board with the original Arduino Mega 2560 R3, however, the size will be larger. This is the reason why we ship MewPro Iliad with Seeeduino Mega.

Seeeduino Mega can run in either 5V or 3.3V logic. Iliad shield itself has a voltage translator so you can set Seeeduino Mega’s voltage, for which there’s a slide switch, to either voltage. However, according to Atmel’s ATmega2560 documentation 16MHz is “overclocking” when 3.3V so we recommend to use the board in 5V logic.

Source code for sync generator is downloadable as a zip file from here:

The code requires the following two external libraries to compile:

(Note: The IRremote library conflicts with RobotIRremote library in the standard Arduino IDE. So please delete
if you encounter some issues.)

To compile/upload is easier than MewPro4 application because it is nothing but an Arduino Mega 2560 clone. So please search the net for tutorial for it if you need.

Let’s Sync!

Everything is ready if you’ve done the above steps (If you bought all the items from our shop then installing software is not necessary).

Iliad board needs one CR2032 button battery to keep date and time. There’s a holder for it at the back of the shield. Please take care + (plus) side is the far side from the board (there’s a curved + mark both on cell and holder). The battery is expected to last two or three years.

Connect USB cable between USB battery (or wall charger) and Seeeduino Mega with Iliad. LCD should light and show “MewPro Iliad” and its software version. If it doesn’t show anything then please try to turn the potentiometer marked 103 for contrast or 102 for brightness.

After the start up message “MewPro Iliad” is shown, you can use it as if it were a real GoPro Hero 4 Black. Camera’s side button for setup corresponds to the SETUP momentary switch, shutter to SHUTTER, and mode to MODE.

(Note: To power on all the camera long press MODE as well as to power off.)

Furthermore, there’s an extra menu that real camera doesn’t have. You can enter to the menu by pressing SETUP while the start up message is shown. The extra settings consist of:

  1. Date/Time – Setting date/time to on-board real time clock chip
  2. Reset – Reset Iliad to factory default
  3. Mount microSD – Resetting all the MewPro 2 board
  4. Learn IR code

By using the last menu item Iliad can learn any IR remote’s code (from TV remote or Video remote etc.) so you can control GoPros with your favorite IR remote controller.

Also resetting all the MewPro 2 board has the same effect to detaching all the MewPro 2 from cameras. This is usually very convenient if you fix up all the cameras in a rig.



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Hero 4 Black Genlock

Hero 4 Black genlocking is demonstrated in the video. The system uses MewPro 2 and up-coming sync signal generator.

The prototype system consists of a sync generator (at the left), three GoPro Hero 4 Black + MewPro 2’s, cables etc. And it is perfectly controlled by an IR (Infrared) remote as in the clip : Power On – Mode Change – Start Recording – Stop Recording – Power Off. The prototype as well as up-coming sync generator is based on Arduino Mega 2560 and will be an open hardware/software as our other products.

Note: The system will work with any number of cameras but can only shoot in the following two video modes (the restriction is due to camera’s firmware).

  • 2.7K 4:3 30fps NTSC / 25fps PAL
  • 1440p 60fps NTSC / 50fps PAL


We are currently designing a PCB for the product so please wait until it appears in our shop. 🙂

This post is outdated. We are already selling Iliad in our shop. Please refer more recent post for info.