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

Additional resources to get started with the SATS-MINI:

SATS-MINI Software Downloads
Current Version: 1.3.6

Download Version 1.3.6 - Current Production Release

Updates for version 1.3.6 - This is a critical update - This update adds support to the new V2.3 SATS-MINI hardware that features an upgraded barmetric sensor. It also fixes a bug in the Real Time Clock library that was causing occational error conditions during startup. The startup error caused the real time clock I to fail to initialize and instead go to the error state with a pulsing purple light. The probability of this error was fairly low overall, perhaps one in 600 startups. However there are some devices in the field where the chances of the startup error are much higher, perhaps 5%. A side benifit is the startup time is faster and more consistent.

IMPORTANT - Best Practices - The SATS-MINI includes features that allow it to automatically turn on in the armed state and be ready to go when external power is applied via CH3 or CH4. When power is removed, the SATS-MINI can be programmed to automatically turn off after a period of time. However, even while the SATS-MINI has these features, it is not set and forget! It is STRONGLY recommended that the pilot always check the SATS-MINI for proper operation before takeoff. If an unrecoverable error is detected, the SATS-MINI will hold in the ERROR state (pulsing purple light) and will not monitor the flight. In this case, simply power cycling the SATS-MINI will clear the error. In testing over thousands of power cycles, the odds of this occurring are very small; however, it is still best to always have a pre-flight check to ensure the SATS-MINI is ready to go.

Upgrading: See Install Shooty Chute Windows UI and Updating the Firmware below.

Previous SATS-MINI Software Releases

Download Version 1.3.5

Updates for version 1.3.5 - This release makes further improvements to the IMU performance and fine tunes reading the rotation quaternion, gyro and accelerometer. Other updates include:

IMU update improves the free fall detection, making it more reliable in some corner cases.
Order of internal processing is further optimized to shorten detection latency.
Logging is improved. In particular when using Terse mode, when critical events occur, the Status Detail line is written. Status Detail is the line with all the sensor data, calculated rotation of X, Y, Z and system voltages. Events that now have a Status line are:
- Changes between Safety and Armed
- Low power warning or return to normal power
- Flight mode changes between multicopter or fixed wing
There is a minor update to the Shooty Chute log reader so it is more resistant to log data issues.

Download Version 1.3.4

Updates for version 1.3.4 - This is a bug fix for hardware V2.2 firmware that affects the IMU. The sample rate for the IMU was lower than it should be and is now fixed. The lower rate caused latency in detection in some cases. If the rotation rate is high (greater than 120 rpm), such as when a rotor fails on a small drone like the DJI Mavic 2, there was a potential for sampling aliasing, causing the angular detection to lag the actual angular total. This could lead to trigger delays by as much as 0.3 seconds in cases with high rotation speed. The update addresses this issue, and there is no longer any delay - even at high rates of rotation. After this fix, hardware Version 2.1 and Version 2.2 now have identical detection latencies under all conditions.

Other updates include:

All data returned by the IMU is now validated. Invalid IMU data samples are now skipped to avoid errors when converting the data to Euler angles where possible divide by 0 errors could occur.
The progress color (pink LED color) now flashes when dumping the log to the Shootychute UI. It also flashes when, upon startup, the log is scanned in case the previous log was not completed correctly. This operation can take several minutes in the case of a large log file. To the user, the SATS may appear to be hung up, and the user may reset the SATS in this case. Note that erasing the log file is a single operation, so the pink LED will not flash in this case.
The new Shootychute UI 1.3.4 can now communicate with all SATS-MINIs running any 1.3.X firmware versions. As such, there is no need to upgrade Shootychute unless the software changes to 1.4 or more or where we recommend the upgrade due to a feature change.

We recommend this as a critical bug fix; all users of the newer SATS-MINI with serial numbers from SA0193 and above should apply this update. We also recommend that all SATS-MINI with software versions before V1.3.1 upgrade in any case to Version 1.3.4 to stay current with all updates.

Download Version 1.3.1 or Download Version 1.3.2 - As described below, 1.3.1 adds support for a new, higher performance IMU in V2.2 hardware. Software version 1.3.2 fixes a regional issue in the Shooty Chute UI.

Updates for version 1.3.1 - This version fixes some minor issues from 1.2.2. However, the largest change is added support for both the previous IMU (hardware versions 1 - 2.1) and the new IMU in version 2.2 of the hardware. Startup time is now more consistent. The IMU also has the ability for continuous calibration and automatically saves IMU calibration information for the next startup.

Updates for version 1.3.2 - The SATS-MINI firmware for this version is functionally identical to 1.3.1; however, the Shooty Chute UI has an important improvement. We've received reports from some international customers that, when the UI started, it would immediately throw a .NET exception and stop. The issue occurred when customers ran the Shooty Chute UI in a Windows system with a regional setting that uses a comma (,) for the decimal separator instead of a period (.). Many EU and other Eastern European countries can use this regional setting.

For upgrades from any 1.2 version, we do recommend downloading V1.3.2. If you recently received a SATS-MINI with Version 1.3.1 and are not experiencing any issues, you do not need to upgrade to Version 1.3.2. The configuration settings between 1.3.1 and 1.3 2 are exactly the same.

Download Version 1.2.2 - This release has the updates from 1.2.1 as well as a couple minor bug fixes.

Version 1.2.2 New Features - This release adds support for Fixed-Wing and VTOL aircraft to the SATS-MINI and more.

Fixed Angle Detection - A new detection algorithm, called Fixed Angle, is now available. Ideal for fixed-wing applications, you can specify the acceptable flight envelope for your aircraft. Detection parameters available are Pitch Forward, Pitch Back, Roll Left and Roll Right. In addition, the rate of roll in degrees per second can be specified for all four pitch directions.
Dual Setup Support - To support VTOL, you can specify a channel allowing both multicopter rotation detection for take off (multirotor) and fixed angle detection for forward flight (Fixed-Wing) to be switched between during flight. Each setup is completely independent, allowing any combination of detection types to be used in each of the two setups. Even better, the autopilot can signal the SATS-MINI which setup mode to use while in flight. Dual setup support can also be used in any case where you want two different dedicated setups for different types of flying. For example, in a multicopter for precision videography or for sport flying.
Logging Support for Thousands of Flights - V1.2.0 also adds a new Terse Logging feature allowing over 50,000 flights to be flown before you need to erase the log file. With Terse Logging enabled only Log Events are logged for normal flights. But if there is a parachute trigger the SATS waited to the log the previous 100 detail logging entries, the trigger event details, and then the next 30 seconds of detailed flight data. Since a normal flight only required about 50 bytes of log memory you can fly well over 50,000 normal flight before the memory is fill. If there is a parachute trigger event the detailed log information just prior and after the trigger event are available for download.
Automatic Log Erase - This option if enable will automatically erase the log once it is full. With this enabled you never have to worry about your flight log being full and missing a parachute trigger event.
Trigger Delay can now be set for up to 16 seconds - This allows the SATS-MINI to be used as a timer between multi-stage parachute deployment. For example with a high speed flights a small drogue chute is first deployed to slow down the drone or even a rocket. Then after up to 16 seconds the main chute can be deployed.

Bug Fixes:

Logging bug fix: In testing we found a subtle data sensitivity that can cause the SATS-MINI firmware to think the log flash memory is full, even while it is not. The probability of this happening was data dependent and had a probability of 1.17% of the time for each flight. There was no core operational risk to the SATS due to this issue except if there was a trigger at the right time the log may not be available.
Voltage Logging: Voltage measurements in the log were offset by approximately 30mv higher. This is due to a bug in a low level core library.
Performance Bug: When the SATS triggers there was a logic ordering issue that could delay the parachute channel from reacting by between 40 to 80ms. This has been fixed.

Upgrade note: Upgrading from 1.1.2 to 1.2.0 is supported. Releases prior to 1.1.2 should first upgrade to 1.1.2 and then upgrade to 1.2.0. If you are having problems upgrading, contact Fruity Chutes support and we will assist.

Download Version 1.2.1

Download Version 1.2.0 - Pre-release of 1.2.1 - This release was an interim release between 1.1.2 and 1.2.1. Version 1.2.0 had an issue with version 2 hardware that does not have the real time clock. There was an initialization problem when the RTC was not present causing the SATS-MINI to go into the ERROR state.

Download Version 1.1.2 - Important - This release fixes some critical bugs reported by the field and it is essential to install this update. This fix only affects the SATS-MINI firmware; the Shooty Chute UI functionality is the same as V1.1.1. If you already have V1.1.1 of Shooty Chute installed, you do not need to reinstall the V1.1.2 of the Windows UI. There are no core feature changes between versions 1.1.1 and 1.1.2.

Bug Fixes:

Logging Bug

When shutting down the SATS-MINI while Armed and logging, there was a bug related to closing out the current log properly. In some cases, log data could still be written to the flash memory after the shutdown is triggered, and it could write fragments of data and cause problems with the next power-up.
Not properly closing out the log can then lead to the next log number jumping to a random log number.
In some cases, it can cause the SATS-MINI to not properly export all logs, so some may be missing.

IMU Initialization

During burn-in cycle testing, we would occasionally see an issue where the IMU is not initialized correctly despite all the IMU self tests successfully passing. This would cause the accelerometer data to read zero for the X / Y / Z axis and, when armed, could lead to a false trigger. The bug fix implements a more rigorous set of secondary testing that checks the IMU accelerometer and sees that the magnitude of X / Y / Z is between 0.9G and 1.1G of acceleration. If an error is detected, the IMU is reinitialized again until the secondary testing passes. If there is a chronic inability to get the IMU to initialize, the SATS-MINI will enter the ERROR status and be non-operational.

Download Version 1.1.1 - First Production Release - Version 1.1.1 is considered our first non-beta production release and has many improvements over previous versions. Included are a number of new features both for the SATS-MINI, and the Shooty Chute UI. There are also some bug fixes. We urge all SATS-MINI users on 1.0.XX beta versions to upgrade. New in this release is support for SATS-MINI V2.1 Hardware! The new version of the SATS-MINI adds a real time clock (RTC), so logging can be time-stamped when various log events happen, such as log start, trigger event, power events, and shutdown events. The RTC draws just 40 nano-amps and is very accurate with a temperature and voltage corrected time base. Once set, the RTC can run indefinitely as long as the LiPo battery stays connected and has even the most minimal charge - even below 3.0V. The V1.1.1 Shooty Chute UI includes a button that sets the RTC time to your PC time.

Version 1.1.1 SATS-MINI Operational Features:

Configurable automatic shutdown after external power removal. In V1.0.29 the turn off time was set for 2 minutes. Now this is configurable for between 15 seconds to 10 minutes.
Automatic power-up in Safety / Armed. This feature makes sure that when the SATS-MINI is powered up, it is always ready to fly. This removes the possibility of powering-up and the user forgetting to arm the SATS-MINI. This feature should be used in conjunction with the Safety features.
Comprehensive error reporting. There is now more error detection at powerup to ensure all the sensors are working and the IMU has no errors. If there is an error, the status LED will flash purple at startup, and the SATS-MINI can not be armed. Connecting to the new Shooty Chute UI, the errors are displayed on the dashboard.
Variable Log Rate. You can now configure the detail flight logging rate for the SATS-MINI to 5 Hz, 10 Hz (default), or 20 Hz. Below is the log capacity for each rate:

5 Hz logging capacity: 12hr 25min
10 Hz logging capacity: 6hr 49min
20 Hz logging capacity: 3hr 6min - This is useful when doing parachute system testing or other testing and you want the best resolution possible.

Version 1.1.1 SATS-MINI Trigger Features:

Primary Axis Tolerance maximum is now 90 degrees. This can be used in conjunction with Tumble rotation of 90 degrees, providing a fast trigger if the drone tips just 90 degrees. This may also be useful for VTOL or fixed-wing, where a complete rotation is unlikely.
Altimeter Based Fall. This trigger watches for a given descent distance occurring within a given time. The default is a fall of 12 meters of fall happening in 1 second or less. This trigger guards against what can be described as a slow-motion crash where the done is not in freefall or completely out of control but, instead, descends at an unsafe rate. For example, when the LiPo power on the drone is nearing complete discharge.
External Voltage Monitor. This allows you to connect your drone's main LiPo battery voltage to the expansion port pin 8. The Shooty Chute UI lets you configure your minimum acceptable battery voltage. When the feature is enabled, the SATS-MINI will trigger the parachute if the external voltage monitor falls below the threshold for 0.5 seconds. The maximum voltage that can be monitored is 33.2 volts, allowing you to monitor up to a 6S battery.

Bug Fixes:

Sometimes at startup, the IMU could come up in an error state. We discovered that one of the Magnetometer calibration values could sometimes be out of bounds and cause this. Code was added to ensure this over-range IMU calibration value is limited when needed. Even with this, the IMU self-calibrates quickly and resumes normal operation in just a few seconds.
Error detection for the IMU was not properly watching for all the initialization errors in some cases.
Fixed a corner case in the rotation detection algorithm when using small Tumbling angles, such as 90 degrees, along with large Yaw rotation angles, such as 540 degrees. In certain combinations of movement, this could cause problems when the Primary Axis Tolerance is exceeded, thereby causing the parachute to eject. We have no reports of any customers having this issue. We recognized the issue in our own testing.
Better detection when using a mis-matched version of the SATS-MINI firmware and the Shooty Chute UI to alert the user of the problem. You should always be using the same version of all the software.

Download Version 1.0.29 (Beta 3)

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 you're 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 requires 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.

We strongly recommend that all V1.0.27 users upgrade to the 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-MINI. This version must be used with the version 1.0.30 Shooty Chutes Windows UI, so be sure to install this. The installer will seamlessly upgrade older versions. Again, see the notes below regarding upgrading the SATS-MINI and migrating your settings to the new version.

After upgrading and restarting, the SATS-MINI will power-up in the Error state and will flash purple. With the new Windows UI, go to Tools - Factory Reset to update the SATS-MINI EEProm and Flash memory. After restarting, the SATS-MINI should power-up in Idle quickly. Sometimes, after factory reset, the SATS may not immediately restart. In this case, force the SATS-MINI off using a paper clip, after which turning on the SATS-MINI should be fine.

Download Version 1.0.28 (Beta 2)

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

New in V1.0.28 is an optional feature that allows the SATS to auto-turnoff after external power is removed. Coupled with the auto-on when power is applied, this allows 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 itself off. With this feature enabled, you don't need to manage the SATS_MINI power; it will automatically turn on and off with your drone's power. If there is a complete loss of power to your autopilot, this likely means the drone is going to lose control and crash. The 2 minute wait time allows the SATS-MINI to detect the drone falling and trigger the parachute before the unit turns off.

Download Version 1.0.27 (Beta 1)

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.

Diagram of SATS-MINI next to the real device.

IMPORTANT - READ FIRST FOR NEW SATS-MINI USERS - 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, charge the SATS-MINI via the USB port. We DO recommend thorough ground testing before flight to validate operation. See the instructions below for basic operation. If you have any questions about the device, please contact us!

The Sentinel Automatic Trigger System (SATS-MINI) has many complex programmable features that can be setup using the Shooty Chute Windows UI program. Once the configuration is uploaded, the only thing required to fly and protect your drone is to turn on the SATS-MINI. Before you fly, ensure that 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 your 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:

Safety Altitude - This is set to 0 so the altitude-based safety is not active. After testing, you may want to set this to 10 meters so the SATS stays in safety until 10 meters above ground level (AGL). Above 10 meters, the SATS-MINI will auto-arm. Download the flight log file to verify proper operation.

External Power Auto-Shutdown - It is generally cleared. For some parachute systems, this will be enabled. For example, the Inspire 1 or Inspire 2: these bundles have external 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 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 launchers 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 this 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 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 a PWM trigger signal so you can remote eject the parachute from the Skycat rescue radio. If the Nano is not installed, 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 almost all drones, such as 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 Shooty Chute Windows UI to edit the configuration. See the SATS-MINI Users and Programing Guide for details on how to use the program.

SATS-MINI Basic Operation

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

Diagram of the SATS-MINI

To turn on the SATS-MINI press and hold the System Mode button for 2 seconds. Once the indicator lights come on, release the button. 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 before changing.

To Turn Off the SATS-MINI, quickly press and release the System Mode button. The SATS-MINI will beep twice: high then low. After this, 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 states. The beeper will sound as well.

Install Shooty Chute 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. You will need to agree to the End User License Agreement.

Using the Shooty Chute UI

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

2 - Start Shooty Chute.

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

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

Control Panel

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 restarting, the status LED will flash Green, and the UI Drone will track the movement of the SATS-MINI. When upgrading the SATS-MINI firmware, we recommend that you do “Tools - Reset to Factory Defaults.” The software release will indicate when this is needed.

Updating the Firmware to a New Version

The SATS-MINI is always shipped with the latest firmware software. When new versions are available, the firmware installs for the SATS-MINI are provided as a self installing UF2 file format.

Before you start:

Before upgrading, save your current SATS-MINI setup to your hard drive, and download your log file if you want to save it. After you upgrade, you can reload your configuration, saving you setup time. Always test your configuration thoroughly before flight.

Before upgrading the SATS-MINI, install the new Shooty Chute UI. You will need this in order to complete the Firmware upgrade. The new UI will not work with pre 1.2.X firmware, so do not connect to the SATS-MINI before upgrading the firmware to the latest version.

In order to install:

Power-up the SATS-MINI and connect the USB cable. You should hear a beep, indicating that the USB port is recognized.
Before you start, make sure the SATS-MINI is in the Idle state; the green light should be flashing.
To load the firmware, you first need to put the SATS-MINI into the bootloader mode. To do this, use a paper clip or other small tool and press the reset button through the clear bezel twice within 1 second or less. There is an access hole in the SATS-MINI case to reach the Reset button (RST). 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.
Open the release folder on your PC. Drag the ATS.UF2 file into the FEATHERBOOT folder. You should see the red light flicker, and the SATS-MINI will restart.
The SATS-MINI will power up in the Error state (Purple pulsing). The UI will tell you you need
Connect the Shooty Chute UI and do the Factory Reset in the Tools section.

To Configure the SATS-MINI

For detailed information about setting up and programming the SATS-MINI download the SATS-MINI Users and Programming Guide with VTOL PDF

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

2 - At this time, you can reload your saved setups.

3 - You can now do any other configuration items needed. After making a change, be sure to upload to the SATS-MINI, which will automatically restart the unit.

General Settings

Advanced Settings

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

SATS-MINI Primary Axis Calibration

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

Mount the SATS-MINI on your drone. Any orientation is okay.
Turn on the SATS-MINI and first initialize the IMU magnetometer by rotating the SATS-MINI (or rotating your drone) a few rotations around all three axes. 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.
This next step is optional and is not required for proper SATS-MINI operation. In order to have the SATS-MINI precisely track your drone movement (so the Shooty Chute 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.
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.
Upload that to the SATS-MINI and restart the SATS-MINI.
Reconnect the UI and the SATS-MINI. 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 will be exactly matched by the UI Drone. It’s key that the IMU is internally calibrated (step 2). If it does not face away from you, the IMU magnetometer 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.

Important: When using the Fixed Angle detection the calibration, offset is not considered. The SATS-MINI must be mounted in the native IMU orientation onto the aircraft. See the SATS-MINI Product Guide for details.

SATS-MINI Log File

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

When the SATS-MINI is in safety or armed trigger events, flight data and other events, such as low power, are logged to the onboard Flash memory. The Flash memory will hold approximately 6 hours of detailed log data when running at 10Hz. Once at 30 minutes or less log space available, only critical events are logged. To transfer the log to your hard drive, do the following:

Connect the Shooty Chute UI to your SATS-MINI. Then go to Tools - Dump Log.
Enter the file name to save to. The dump is in CSV format and can be easily viewed in Excel.
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.

New! - If you enable Terse Logging, only key events are logged for each flight and take very little log space, so many thousands of flights can be logged. And if you have a parachute trigger the detail logging immediatly before and after the parachute trigger are saved to the log file. Also enable Auto Erase to automatically erase the log file once it is full.

Using the SATS-MINI with Pixhawk Based Systems

The Pixhawk hardware platform can work well with the SATS-MINI depending on the software stack used. The key feature needed is the ability to stop the rotors when the parachute is ejected by the SATS-MINI. Additionally, the SATS-MINI can be driven by the Parachute Channels output of the Pixhawk to provide external trigger of the SATS-MINI and eject the parachute. The default SATS-MINI configuration has CH4 setup for external trigger 2000us, 20% tolerance. The Pixhawk parachute output also uses a 2000us PWM pulse width. In addition to this, the Pixhawk 5V power pin on the Parachute output channel will feed power to the SATS-MINI to keep the LiPo battery charged.

PX4 Software Stack - The latest version of the PX4 now has support for Flight Termination built in. The feature is not yet merged into an official branch (V1.10 is the latest, but does not have support), but it is in Master. Here is the documentation on how to setup Flight Termination:

https://docs.px4.io/master/en/advanced_config/flight_termination.html - General article about flight termination done by the PX4 firmware

https://docs.px4.io/master/en/config/safety.html#external_ats - External ATS Integration to support Flight Termination. This lets the SATS-MINI stop the rotors. Connect one of the PWM parachute out channels to Aux5 or Main5. Termination happens when the SATS-MINI assets a 2000us signal (135 degrees).

https://github.com/PX4/PX4-Autopilot/pull/13726 - Bitbucket pull request outlining some of the details.

ArduPilot Software Stack - This software stack has parachute support already, but it does not have external Flight Termination allowing a tight integration with an external ATS like the SATS-MINI. We have submitted an enhancement request to have external Flight Termination supported, but there has not been any effort yet to complete this. Here is the request:

https://discuss.ardupilot.org/t/add-external-flight-termination-feature-to-autdupilot-per-astm-f3322-18/50976

If this seems valuable, please advocate for this to the ArduPilot development community so we can get this implemented.

Use a Relay for Flight Termination - It's possible to use an external relay to cut power to the autopilot or the ESC power to stop the rotors. Here is a schematic to do this. It works with the DJI A3 autopilot.

SATS-MINI Configuration with Pixhawk and Flight Termination Relay.pdf

Sample SATS-MINI configuration with flight termination support - SATS-MINI Configuration XML - Right click and save to your hard drive. Then upload to the SATS-MINI. Be sure to thoroughly test your setup.

Testing and Verification

After setting up your SATS-MINI, be sure to test and verify all operations. Use the Shooty Chute UI for some of these tests.

Test for rotation detection - This may be easiest to do before the SATS-MINI is mounted to the drone. After arming with the red light flashing, flip the device end over end. The SATS-MINI should trigger, showing a blue flashing light. You can use a Servo to verify movement.
Test for Free Fall detection - After arming, toss the device into the air, being careful not to rotate it. After about ½ second, the SATS-MINI should trigger to a blue light.
Make sure the SATS-MINI IMU is calibrated. In the Shooty Chute UI main panel, note that the line Calibration Status says “Calibrated.” All units are calibrated at the factory and should not need recalibration. If it does not indicate calibration or you see the Error indicator show that there is a IMU error, contact Fruity Chutes for assistance.
With the drone level on the ground, using the Shooty Chute UI, check that the virtual drone is also level.
Rotating the drone will cause the virtual drone to rotate.
Test the parachute channel endpoints. You can toggle the SATS-MINI states using the mode pulldown. If you have an energetic parachute system like CO2 or Pyro, be sure to disconnect these first. Use a servo to test for channel operation.
If you are using advanced features, like altimeter safety or overrides, be sure to verify these.
If you are using an external trigger input, be sure to test again for proper operation.
Dry run your setup - If you are concerned about possible false triggers due to sensitive setup parameters, test fly the SATS-MINI on your drone first and make sure the device does not trigger accidentally. Fly the drone at the edges of the flight envelope to see if you can false trigger the SATS. If you do see a false trigger, then download the flight log to see the conditions. You may need to adjust the trigger settings.
After testing, download the Log file and verify for expected operation.

Best Practices

Unless you are using an external 5V input power feed, make sure you charge the SATS daily before flight. Charging can be done via USB cable to your computer. Charging takes about 90 minutes. The Yellow charge light will extinguish once charged.
Before flight, ensure the SATS-MINI is sufficiently charged. The SATS-MINI LiPo is sufficient to operate the unit for up to 6 hours of operation (when not using the Nano receiver). When there is under one hour of battery life remaining, the device will chirp twice per second. Do not fly if the SATS-MINI is chirping since the battery life may be too short.
Check the parachute launcher and connection to the SATS-MINI before flight.
Before takeoff, make sure the SATS-MINI is armed (or in safety, if used).

IMPORTANT - The SATS-MINI includes features that allow it to automatically turn on in the armed state and be ready to go when external power is applied via CH3, or CH4. When power is removed, the SATS-MINI can be programmed to automatically turn off after a period of time. However, even while the SATS-MINI has these features, it is not set and forget! It is STRONGLY recommended that the pilot always check the SATS-MINI for proper operation before takeoff. If an unrecoverable error is detected, the SATS-MINI will hold in the ERROR state and will not monitor the flight. In this case, simply power cycling the SATS-MINI will clear this. In testing over thousands of power cycles, the odds of this occurring are very small. However, it is still best to always have a pre-flight check to ensure the SATS-MINI is ready to go.
After flight, disarm and turn off the SATS-MINI to save battery and log space.

What To Do After Parachute Deployment

If the SATS-MINI triggers a parachute deployment, be sure to disarm the SATS-MINI and download the log file. The log events will show what condition caused the parachute to eject. If you like, please send the log to Fruity Chutes and we can do a post-deployment analysis to verify operation. In this case, it would be helpful to indicate the drone type, weight, parachute system, etc., as well as flight conditions.

Contact us if you require any assistance.

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

SATS-MINI Software DownloadsCurrent Version: 1.3.6

Download Version 1.3.6 - Current Production Release

Previous SATS-MINI Software Releases

Get Started Here

Preloaded Default Configuration

SATS-MINI Basic Operation

Install Shooty Chute Windows UI

Using the Shooty Chute UI

Updating the Firmware to a New Version

To Configure the SATS-MINI

SATS-MINI Primary Axis Calibration

SATS-MINI Log File

Using the SATS-MINI with Pixhawk Based Systems

Testing and Verification

Best Practices

What To Do After Parachute Deployment

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

SATS-MINI Software Downloads
Current Version: 1.3.6