Sentinel Automatic Trigger System (SATS-MINI) Quick Start Guide and Resources

Use this resource to get started with the SATS-MINI

SATS-MINI Quick Start Guide PDF

SATS-MINI Product Guide PDF

SATS-MINI Users and Programming Guide PDF

Software Downloads - Current latest version is 1.0.28

Download Version 1.0.29 (Beta 3) - Current Version

IMPORTANT UPGRADE INFORMATION FOR V1.0.29 - V1.0.29 has an important change for users of the Pixhawk with the PX4 software base.  When the Pixhawk powers up all the outputs produce a single 2000us PWM pulse regardless of the settings.  If your using a channel from the Pixhawk into the SATS for an external parachute trigger input to the SATS this can cause the SATS to eject the parachute.  Version 1.0.29 now required 3 PWM pulses in a row that satisfy the external PWM trigger input in order to eject the parachute. V1.0.29 has no configuration changes from V1.0.28 and will upgrade seamlessly.

If you still have V1.0.27 we strongly recommend that all these users upgrade to this latest version.  While 1.0.27 does not have any problems that hinder critical operation there are some important bug fixes regarding some UI interactions with the SATS.  Also features regarding secondary channel types have some minor bug fixes.

For people upgrading from V1.0.27 follow the notes below for installing the UF2 firmware file into the SATS.  Also this version must be used with the latest ShootyChutes Windown UI so be sure to install that.  The installer will seamlessly upgrade older versions. Again see the notes below regarding upgrading the SATS and migrating your settings to the new version.

After upgrade and restart the SATS-MINI will power up in the Error state and pulsing purple.  With the new Windows UI go to Tools - Send Default Configuration to the SATS.  After restart the SATS-MINI may wait several minutes with a solid purple light while it scans the flash memory to upgrade the logging format.  This happens only once and after this is finished startup will be back to normal.

Past Versions

Download Version 1.0.28 (Beta 2)

V1.0.28 has some important bug fixes regarding some UI interactions with the SATS.  Also features regarding secondary channel types have some minor bug fixes.

New in V1.0.28 is a feature (optional) that allows the SATS to auto-turnoff after external power is removed.  This coupled with the auto-on when power is applied allow you to connect your autopilot +5V power to Channel 3 or 4 power pin (pin 2).  When the autopilot supplies 5V power the SATS will automatically turn on. When the auto-pilot turns off the SATS will then wait 2 minutes and turn it'self off.  So you don't need to manage the SATS_MINI power, it will automatically turn on and off with your drone power.  If there is a complete loss of power to your autopilot this likely means the drone is going to loose control and crash. The SATS-MINI will detect the drone falling and trigger the parachute before the unit turns off.

Download Version 1.0.27 (Beta 1)


We always ship the SATS-MINI pre-loaded with the latest software available and with the default configuration.  If you ordered the SATS-MINI as part of a bundled product, like the Inspire 2 or Mavic 2 parachute the SATS-MINI comes pre-set with the Z axis orientation set. Also the channels come pre-configured for proper operation.  Before flight do charge the SATS-MINI via the USB port. We DO recommend through ground  testing befor flight to validate operation. See the instructions below for basic operation. If you have any questins about the device please contact us!

Get Started Here

Here we give you the most important information you need to get up and going fast. Much of this information here is also covered in the SATS-MINI Product Guide and the SATS-MINI Users and Programming Guide so be sure to refer to these for more detailed information.

The Sentinel Automatic Trigger System (SATS-MIN) has many complex programmable features that can be setup using the ShootyChute Windows UI program. Once the configuration is uploaded the only thing you need to do to fly and protect your drone is to turn on the SATS-MINI. Also before you fly be sure the SATS-MINI is in the operational Safety / Armed state so the parachute can trigger. After flying disarm the SATS-MINI and power down. Later you can download your flight log to your PC using the Shooty Chute app. If you parachute is needed the flight log becomes an essential part of diagnosing what the failure is.

Preloaded Default Configuration

The SATS-MINI comes preloaded with a default configuration that will work for most drone applications. In this configuration the channels are programmed as:

Saftey Altitude - This is set to 0 so the altitude based safety is not active.  After testing you may want to set this to typically 10 meters so the SATS stays in safety untill 10 meters off the ground. Above 10 meters the SATS-MINI will auto-arm.  Download the flight log file to verify proper operation.

External Power Auto-Shutdown - Is is generally cleared.  For some parachute systems this will be enabled.  For example the Inspire 1 or Inspire 2, these bundles have extrnal battery power supplied by the Skycat V3 Trigger (connected to Channel 3).  The SATS-MINI will automatically turn on and off with the application and removal of the external power.  If you use the SATS-MINI with the Pixhawk you may also want to use this feature.

Channel 1 - Trigger, Trigger output, PWM, servo sweep 45 degrees to 135 degrees, no delay, 5V Power Out - Use this channel for the Harrier or other launcher that needs a servo PWM signal

Channel 2 - Trigger Delayed, Trigger Output, PWM, servo sweep 45 degrees to 135 degrees, 500ms delay, 5V Power Out - Use this channel for your PWM output if you want to delay the parachute trigger. In that case you would use Channel 1 for Flight Termination, then Channel 2 to eject the parachute 500ms later.

Channel 3 - Skycat V3 Trigger, Trigger Output, PWM, servo sweep 45 degrees to 135 degrees, no delay, 5V Power In - This channel is preconfigured for the Skycat V3 trigger. Channel 3 can accept power in from the V3 Trigger. And at the same time this channel will provide the PWM output to launch the parachute.

Channel 4 - Nano RX, Trigger Input, PWM, Trigger PWM 2000us, 10% Tolerance, 5V Power In - The optional TBS Nano receiver, if installed, will use this channel in order to provide an PWM trigger signal so you can remote eject the parachute from the Skycat rescue radio. If the Nano is not installed then you can use Channel 4 for any other virtual IO feature.

Failure Detection Settings used to trigger the parachute are defaulted to:

  • Tumbling (Non-Primary Axis) - 360 degrees roll in under 2 seconds
  • Yaw (Primary Axis) - 540 degrees rotation in under 2 seconds
  • Free Fall - Accelerometer fused X/Y/Z magnitude threshold <= 0.3G for >= 0.5 seconds

These settings will work for most all drones like the Mavic 2, Phantom 4, and other DJI drones. The settings will not result in false triggers for normal flying conditions.

To change the settings use the ShootyChute Windows UI to edit the configuration. See the SATS-MINI Users and Programing Guide for details how to use the program.

SATS-MINI Basic Operation

Below is a renerding of the SATS-MINI case and the various features.

To turn on the SATS-MINI press and hold the System Mode button for 2 seconds. Once the indicator lights come on release. The SATS-MINI will come up in the same System State it was in when powered down. The mode light may temporarily show solid Purple if there is a startup process that needs to happen before going to the operational state. In rare cases it can remain solid Purple for several minutes so just wait.

To Turn Off the SATS-MINI quickly press and release the System Mode button. The SATS-MINI will beep twice, high then low. After that press and hold for two seconds. The SATS-MINI will do a Triad of beeps and turn off.

To change SATS-MINI operational states press and hold the System Mode button for 1 second and it will transition between operational states. The beeper will also sound.

Install ShootyChute Windows UI

1 - Download the SATS-MINI Windows UI software from our website (link on this page).

2 - Double click on the ShootyChutes.msi file and follow the steps. Windows will complain that the publisher is unknown. Click the links to force Windows to install the software. Tou will need to agree to the End User License Agreement.

Using ShootyChute

1 - First plug in the SATS-MINI USB port to your computer first so the COM port is created. This will also turn on the SATS-MINI.

2 - Start ShootyChute.

3 - The serial port of the SATS-MINI should be listed. Click Connect. The box next to Connect should turn Green.

4 - Physically moving the SATS-MINI should cause the 3D box rendering to track the movements.


NOTE: If the SATS-MINI does not have a valid configuration then the Status LED will pulse PURPLE. In this case you need to send a default configuration to the SATS-MINI and restart. To do this use Tools - Send Default Configuration. After restart the status LED will flash Green and the UI Drone will track the movement of the SATS-MINI. In some rare cases with a software upgrade you may need to use the tool “Reset to Factory Defaults”. The software release will indicate when that is needed.

Updating the Firmware

The SATS-MINI is always shipped with the latest firmware software. When new versions are available the firmware installs for the SATS-MINI are formatted as a self installing UF2 file format. In order to install:

  1. Power up the SATS-MINI and connect the USB cable. You should hear the beep that the USB port is recognized. 
  2. Before you start make sure the SATS-MINI is in the Idle state, the green light should be flashing which is Idle.
  3. To load the firmware use a paper clip of other small tool and press the reset button twice within 1 second or less. There is an access hole in the SATS-MINI case to reach the Reset button. This will put the SATS-MINI into the Bootloader mode and a Drive letter will show up in your Windows File Explorer that says FEATHERBOOT. The status LED will also pulse red. 
  4. Open up the folder. Drag the firmware-<date>.UF2 file into the folder and you should see the red light flicker and the SATS-MINI restart. 
  5. The green idle light will start to flash and the SATS-MINI with be in Idle.

NOTE: Some firmware upgrades require you send a new default configuration to the SATS-MINI due to new features being supported. You should also erase the Log file before going to armed in case there are changes in the Log format.

TIP: Before upgrading save your current SATS-MINI setup to your hard drive.  After you upgrade you can reload your configuration saving you setup time.  Always test your configuration throughly before flight.

To Configure the SATS-MINI

1 - After connecting click Tools - Device Setup. The current setup for the SATS-MINI will be pulled down. 

2 - If you have installed new Firmware be sure to send a new Default Configuration to the SATS-MINI in case the configuration format has changed.

  1. If you have a setup you would like to save you can first save that your local hard drive. 
  2. Then update the configuration of the SATS-MINI by sending a new default configuration - Tools - Send Default Configuration. 
  3. After you send the config power cycle (or reset) the SATS-MINI. 
  4. Reconnect and then load your saved configuration from disk and upload to the SATS-MINI. Also recalibrate the SATS-MINI orientation (see below).
  5. Power Cycle (Reset) one more time and saved config and calibration will take effect. 
  6. It’s also best to clear out the Logs in case any format changes have been made. To do this use Tools - Erase Log

IMPORTANT - Do not use “Send Default Config” unless you have done a firmware update that requires this. If you do need to reset the config you can save your setup first to your hard drive. After the upgrade you can connect, load your config and push that back to the SATS-MINI.

3 - You can now do any other configuration items needed at this time. After making a change be sure to upload to the SATS-MINI and restart the unit.


NOTE: Be sure to ground test any updated you make. It’s less expensive to discover setup issues on the ground rather than in flight!

SATS-MINI Calibration

In order to optimize the SATS-MINI detection algorithm you need to tell the system which way is up. The calibration procedure allows you to mount the SATS-MINI on your drone in any imaginable orientation and it will work the same. Follow these steps:

  1. Mount the SATS-MINI on your drone. Any orientation is Ok.
  2. Turn on the SATS-MINI and first initialize the IMU magnetometer by rotating the SATS-MINI (or rotate your drone) a few rotations around all three axis. The internal Co-processor will then learn the position of magnetic north. If you have a large drone it may be easier to detach the SATS-MINI and rotate it on it’s own, then reattach.
  3. This next step is optional and is not required for proper SATS-MINI operation. In order to have the SATS-MINI exactly track your drone movement so the ShootyChute animated UI drone matches the physical drone movement you will want to orient your drone to face magnetic North. If you have a cell phone compass, or a tool like GPS Essentials it can tell you which way to point your drone. 
  4. Next put your drone in a level position (optionally facing magnetic north) so we can capture the physical SATS-MINI orientation. In the UI go to Tools - Device Setup. Click Acquire in order to capture the raw IMU orientation. You will see angle values populate the X / Y / Z fields. Clicking acquire again should result in consistent values.
  5. Upload that to the SATS-MINI and restart the SATS-MINI.
  6. Reconnect the UI and the SATS-MINI and the UI drone should appear level and the drone arrow will face away from you. If you did step #3 your movement of the drone tilting will be exactly matched by the UI Drone. Also it’s key that the IMU is internally calibrated (step 2). If it does not face away from you the the IMU manetomers may not have been completely settled when you acquired the position. Repeat the calibration process if needed. In any case the Z axis will be very close to optimal for the detection algorithm to work properly after calibration.


If you have a parachute deployment the log file is a critical tool to determine the exact cause of the drone failure.  So managing the log and making sure you can capture flight information is extreemely valuable.

When the SATS-MINI is in safety or armed trigger events, flight data and other events like low power are logged to the onboard Flash memory. The Flash memory will hold approximately 6 hours of detailed log data. Once there is only 30 minutes of log space available only critical events are logged. To dump the log to your hard drive do the following:

1 - Connect the ShootyChutes UI to your SATS-MINI.  Then go to Tools - Dump Log.

2 - Enter the file name to save to. The dump is in CSV format and can be easily viewed in Excel.

3 - Click Save. The message box will tell you once the dump is completed.

After dumping logs are not deleted. Instead new logs are appended and a new log number assigned. You can erase the log using Tools - Erase Log.

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