Troubleshooting and FAQs

1. Connecting over Bluetooth

1.1. My Shimmer pairs, then Windows shows it as “Disconnected”

Applies to: Shimmer3, Shimmer3R

This is normal. Windows connects to the Shimmer only for the few seconds it takes to pair, then shows it as disconnected. The connection that carries data is made later, by Consensys or your own software.

1. Pair the Shimmer in Windows Bluetooth settings. Shimmer3 asks for the PIN 1234.
2. Open Consensys, go to the Live Data tab and connect to the Shimmer from there.

Still stuck? Try 1.2.

1.2. My Shimmer stopped connecting after a firmware or Consensys update

Applies to: Shimmer3, Shimmer3R

A firmware update keeps the Shimmer’s configuration by default, but not if Reload configuration after firmware write was unticked (Consensys User Guide), and a configuration written from Consensys can change it too. If the recording mode is SD log recording only, Bluetooth is switched off and the Shimmer can’t be found.

1. Dock the Shimmer and open Consensys.
2. Select the Shimmer and open Configure.
3. Set the recording mode to one that uses Bluetooth (streaming, or logging and streaming).
4. Write the configuration to the Shimmer, then undock it.
5. In Windows Bluetooth settings, remove the Shimmer, then pair it again.

One PC can stream from up to 7 Shimmers at once over Bluetooth Classic. If you use several Shimmer3R units on one PC, also check that each Shimmer appears in Windows Bluetooth settings only once. Then test each unit on its own.

Still stuck? See 1.3. Then send us the Consensys version, the firmware version, and the LEDs you see when the Shimmer is undocked (3.1).

1.3. My Shimmer is slow to connect, or takes several tries

Applies to: Shimmer3, Shimmer3R

1. Check that the Shimmer’s configuration has Bluetooth on (see 1.2).
2. Bring it within a few metres of the PC, in sight of it. The Shimmer reaches about 10 m; the PC’s own Bluetooth may reach less.
3. Dock it for a few minutes, in case the battery is low, then try again.
4. Try connecting several times. While it waits for a connection, a Shimmer listens for only 320 ms in every 2.56 s, and a Shimmer the PC has not connected to for a long time can take a few attempts. Once connected, it connects quickly again.

Still stuck? Send us the Consensys version, the firmware version, and the LEDs the Shimmer shows when undocked (3.1).

1.4. What Bluetooth radio does a Shimmer use, and how far does it reach?

Applies to: Shimmer3, Shimmer3R

Indoors the range is typically about 10 m. It depends on how both ends are oriented, on what is in between (a body absorbs 2.4 GHz well), and on the PC’s own Bluetooth adapter. One PC can stream from up to 7 Shimmers at once over Bluetooth Classic.

More than 7 Shimmers on one PC: use a second Bluetooth adapter (one for every 7 Shimmers), each with its own Bluetooth driver; we have tested a Toshiba driver alongside the Microsoft one. Pair at most 7 Shimmers with each adapter, and pair each Shimmer with only one of them.

1.5. How much delay does Bluetooth streaming add?

Applies to: Shimmer3, Shimmer3R

Samples reach the PC a little after they are measured, and the delay varies from packet to packet: in our tests it was typically about 25 ms, and up to about 100 ms. So data from several Shimmers arriving at the PC at the same moment was not necessarily measured at the same moment. Use each sample’s timestamp, not its arrival time. See Bluetooth latency in the User Manual.

1.6. My Shimmer won’t connect to my Android phone or tablet

Applies to: Shimmer3, Shimmer3R

1. Charge the Shimmer fully.
2. Switch off the Shimmer and the phone’s Bluetooth, then switch both on again.
3. Remove the Shimmer from the phone’s Bluetooth settings, then pair it again.

Still stuck? Try the steps in 1.3.

1.7. My Shimmer’s COM port isn’t listed in my software

Applies to: Shimmer3, Shimmer3R, with the MATLAB or LabVIEW drivers and other software that connects by COM port

1. Refresh the list of COM ports in your software.
2. Check which COM port Windows gave the Shimmer when you paired it, as described in Finding the COM port in the User Manual, and choose that one.

2. Firmware and the dock

2.1. My Shimmer shows as “Unknown” in the dock, or a firmware update failed

Applies to: Shimmer3, Shimmer3R

A Shimmer that shows as Unknown, with a Bluetooth radio ID of 0000 and a battery of 0%, has usually been left without working firmware by an interrupted update. In most cases you can recover it by programming it again.

1. Update Consensys to the latest release first. A newer Consensys alone fixes some of these cases.
2. Dock the Shimmer, open Manage Devices and select it. You can select it even when it shows as Unknown.
3. Open the Firmware tab and choose the latest firmware under Quick.
4. Untick Reload configuration after firmware write, then click Program.
5. Leave the Shimmer docked until programming finishes. Don’t undock it and don’t close Consensys while it runs.
6. When it finishes, configure the Shimmer again. Because Reload configuration after firmware write was unticked, programming reset the configuration and the calibration to the defaults, so calibrate the Shimmer again too. The data on the SD card is not touched. See Reload configuration after firmware write.

Warning: Shimmer3 and Shimmer3R use different firmware. Programming a Shimmer3 with Shimmer3R firmware, or the other way round, can leave it unrecoverable without returning it to us.

Still stuck? Send us the firmware version you tried, a screenshot of the error, and the LEDs the Shimmer shows when undocked. We may send you a firmware file to program through Other and + on the same tab.

2.2. Programming the firmware fails with an error

Applies to: Shimmer3, Shimmer3R

1. Make sure the Shimmer is switched on. Programming a Shimmer that is switched off fails.
2. With a Shimmer Dock: take the Shimmer out, unplug the dock’s USB cable, plug it back in, then dock the Shimmer again.
3. With a Consensys Base: take all the Shimmers out, unplug the Base’s USB cable and power supply, plug the power back in, then the USB cable, then dock the Shimmers again.
4. Try again. If Consensys can’t find the dock or Base at all, see 5.2.

Still stuck? See 2.1.

2.3. Why does the Shimmer Dock add two serial ports?

Applies to: Shimmer3, Shimmer3R, in the Shimmer Dock

The dock has two USB serial ports, which the PC numbers in order (for example COM21 and COM22 on Windows, or /dev/ttyUSB0 and /dev/ttyUSB1 on Linux). The lower-numbered port is the programming port, which Consensys uses to program and configure the Shimmer. The other connects to the Shimmer’s serial port, for your own software.

3. LEDs, battery and charging

3.1. What do the LEDs on my Shimmer mean?

Applies to: Shimmer3 and Shimmer3R with current LogAndStream firmware

The upper LED shows what the Shimmer is doing. The lower LED shows its health: battery, charging and errors. These are the patterns we’re asked about most:

Older Shimmer3 firmware: before LogAndStream v1.00.003 the lower LED shows the battery level (green, yellow or red), not the charging state, so a charging Shimmer3 can show yellow or green. Updating the firmware gives the patterns above.

Every pattern is listed in LED indicators in the Shimmer3/3R User Manual.

3.2. My Shimmer’s battery runs down quickly or won’t charge

Applies to: Shimmer3, Shimmer3R

1. Make sure the dock is connected to a powered USB port. A Shimmer left in an unpowered dock discharges.
2. Dock the Shimmer on its own and check its battery level in Consensys.
3. Charge it fully, then time how long it runs undocked.

A battery that has been left flat for a long time can fall into deep discharge, and then charges slowly and runs down early. To recover it:

1. In Consensys, program the Shimmer with the Sleep firmware, from the Other tab of the firmware selection.
2. Charge it for 6 to 7 hours, no longer. Undock it, then charge it for another 6 to 7 hours.
3. Program LogAndStream again, stream the battery voltage, and check that the battery is full.
4. Plot the battery voltage against time while the Shimmer runs, to see how fast it discharges.

If it still runs down early, the battery may need replacing: see Battery Replacement in the User Manual.

Still stuck? Send us the battery level Consensys shows and how long the Shimmer runs undocked.

3.3. What battery does a Shimmer have, and can I fit a bigger one?

Applies to: Shimmer3, Shimmer3R

Current Shimmer3 and Shimmer3R units have a 3.7 V, 400 mAh rechargeable lithium battery; early Shimmer3 units have 450 mAh. How long it lasts depends on the sensors, the sampling rate and whether you stream or log: see Battery Life in the User Manual.

Fitting a different battery means opening the unit, which invalidates its warranty, and the charger limits a charge to about 770 mAh. Contact us if you need a longer battery life.

4. Logging to the SD card and getting your data

4.1. Consensys reports an SD card error, or can’t import my data

Applies to: Shimmer3, Shimmer3R

Your data is usually still on the card. Before anything else, make a copy of it.

1. Dock the Shimmer, right-click it in Consensys and choose Open SD. Check that the folder opens in Windows Explorer.
2. Copy the data folder from the card to your PC before trying anything else. On a Shimmer3R you can also connect the Shimmer directly over USB-C and copy the folder from the drive that appears.
3. Update Consensys and the Shimmer’s firmware, configure the Shimmer, and write the configuration.
4. If you use a multi-unit dock, import from one Shimmer at a time.

Still stuck? Send us the Consensys app logs (Settings → Workspace Directory → Open) and the copy of the data folder. See also PC fails to recognise the SD card in the Shimmer Dock User Guide.

4.2. The lower LED flashes green fast when I undock or switch on my Shimmer

Applies to: Shimmer3, Shimmer3R

The firmware can’t read the SD card, or can’t create its folders and files on it.

1. Check that the SD card is inserted properly.
2. Check that it is a card the Shimmer supports: see Choosing a microSD card in the User Manual.
3. Check that the card is not full.
4. Check that the trial name and Shimmer name in the configuration use only letters, digits, dashes and underscores.

Still stuck? Copy the data off the card first, as in 4.1, then try another card.

4.3. The data file is empty after logging

Applies to: Shimmer3, Shimmer3R

Log for at least one minute. The Shimmer writes data to the card in blocks, and a very short session can end before the first one is written.

5. Consensys installation and licences

5.1. How do I move my ConsensysPRO licence to another PC, or another Windows user?

Applies to: ConsensysPRO

A ConsensysPRO licence is activated for one Windows user account on one PC. You can deactivate and activate it as often as you need.

To deactivate it: in Consensys, open Help → Manage Licenses. In the Licensee Activations panel on the right, click the X beside the PC you want to deactivate.

To move it to a new PC: deactivate the licence in Consensys on the old PC, then activate it on the new one with the same key.

To use it under a second Windows user on the same PC: deactivate it under the first user, then activate it under the second.

If the old PC no longer works, or Consensys won’t open there, send us your licence key through our contact page and we’ll release it so you can activate it on the new PC.

5.2. Consensys doesn’t detect my dock or Base after installation

Applies to: Consensys with the Shimmer Dock or Consensys Base, on Windows

The dock and Base connect through an FTDI USB serial driver. If Windows installed the wrong driver, Consensys can’t find them.

1. Unplug the dock or Base.
2. Open Device Manager. Uninstall every USB Serial Converter the dock or Base added (A and B for a Shimmer Dock, A to D for a Base6 or Base15), ticking Delete the driver software for each.
3. Restart the PC.
4. Install the latest FTDI VCP driver, as an administrator, as described in Installing the FTDI driver by hand in the Consensys User Guide.
5. Plug the dock or Base back in and open Consensys.

Consensys does not support virtual machines, because the dock’s serial ports are not passed through to them.

6. Exporting data

6.1. Export to MATLAB (.mat) stays “In progress”

Applies to: ConsensysPRO 2.2.9. Fixed in ConsensysPRO 2.2.12.

When a recording has about 50,000 samples or more per Shimmer, export to MATLAB format doesn’t finish. The .mat files it writes are incomplete. Don’t use them.

• Update to ConsensysPRO 2.2.12 or later, and export the sessions to MATLAB again.
• If you can’t update yet, export the same sessions as CSV instead. CSV export is not affected. Close the progress window when the CSV export finishes.

7. Signal quality

7.1. How do I get a reliable GSR signal?

Applies to: Shimmer3 GSR+, Shimmer3R GSR+

1. Place the electrodes on the palm side of the end segments of the index and middle fingers, on the same hand every session. For participants who move around, the palm (thenar and hypothenar) is a steadier site.
2. Clean the skin lightly and let it dry completely. Don’t use lotion.
3. If you use gel, use one made for electrodermal recording, with about 0.05 M sodium chloride. Don’t use pre-gelled ECG electrodes, or ECG or EEG gel: their salt content is several times higher and alters the skin conductance you measure (Boucsein et al., Publication recommendations for electrodermal measurements, Psychophysiology 49, 2012).
4. Fit the electrodes snugly without squeezing the skin.
5. Keep the cable from moving.
6. Wait 5 to 10 minutes before taking a baseline. Drift in the first few minutes is normal.

Typical resting skin conductance is about 2 to 10 µS. It varies widely between people and between sessions, so compare responses within each participant rather than absolute values across sessions.

More detail is in the GSR+ User Guide.

7.2. A magnetometer axis reads -4096

Applies to: Shimmer3

-4096 means the axis has overflowed: the magnetic field is stronger than the range the magnetometer is set to. Choose a wider magnetometer range in the Shimmer’s configuration.

7.3. Is it safe? Does the GSR+ pass a current through the skin?

Applies to: Shimmer3 GSR+, Shimmer3R GSR+

Yes, a very small DC current flows from one electrode through the skin to the other. The circuit limits it, and even with a single fault it stays far below any level that could cause harm. In normal use it is typically a couple of orders of magnitude below the level a person can feel.

7.4. Does GSR measurement use AC or DC, and don’t the electrodes polarise?

Applies to: Shimmer3 GSR+, Shimmer3R GSR+

The GSR+ measures with a low DC voltage, and polarisation of the electrodes is negligible in practice: see DC-voltage excitation in the GSR+ User Guide.

7.5. Can I put the ECG limb electrodes on the chest instead of the arms and legs?

Applies to: Shimmer3 ECG, Shimmer3R ExG

Yes. Despite their names, all the limb electrodes can go on the torso. Place each one away from the heart, toward the limb it is named after. Putting them on the limbs needs longer leads, which can lower the ECG quality. See Electrode Positioning in the ECG User Guide.

7.6. Can I measure heart rate with a GSR+?

Applies to: Shimmer3 GSR+, Shimmer3R GSR+

Yes. Besides its GSR inputs, the GSR+ has a 3.5 mm jack for an external sensor, such as our Optical Pulse Sensor (finger probe or ear clip). It records a photoplethysmogram (PPG), from which heart rate is estimated with a PPG-to-heart-rate algorithm.

8. Timing and synchronisation

8.1. Does a Shimmer have a real-time clock?

Applies to: Shimmer3, Shimmer3R

Yes. Consensys sets it from the PC’s clock whenever the Shimmer is docked in a Shimmer Dock or Consensys Base, or connected over Bluetooth. Each sample’s timestamp counts from the Shimmer’s own clock, and the real-time clock relates it to the time of day.

A Shimmer3 loses the clock whenever it is reset or switched off; a Shimmer3R keeps it across a reset, and loses it only if it loses power completely. Until the clock is set, the upper LED flashes green and blue together (cyan on Shimmer3R). See Real-time clock in the User Manual.

How closely does it follow the PC’s time? When Consensys sets the clock, it matches the PC’s to within about a millisecond. From then on it runs on the Shimmer’s own crystal and drifts slowly; two Shimmers can drift apart by up to about 43 ms an hour, or about 1 s a day. Setting the clock again (docking the Shimmer, or connecting to it) brings it back into line. For long recordings from several Shimmers, use SD sync, which measures the drift and corrects for it (8.2). See Clock drift in the User Manual.

8.2. How do I synchronise data from several Shimmers?

Applies to: Shimmer3, Shimmer3R

• Streaming over Bluetooth: Consensys timestamps the data of every Shimmer against the PC’s clock, so streams recorded together line up.
• Logging to the SD card: either set each Shimmer’s real-time clock (dock them, or connect, just before the session) so that all record against the PC’s time, or use SD sync: one Shimmer acts as the centre and measures the others’ clock offsets over Bluetooth during the session, so Consensys can align the data precisely afterwards. SD sync uses some Bluetooth power, so it shortens battery life a little. See Synchronised logging across several Shimmers in the User Manual.

Don’t reset or switch off a Shimmer during a synchronised session.

8.3. Can I synchronise a Shimmer with another device or system?

Applies to: Shimmer3, Shimmer3R

Yes. See Synchronising with an external system in the User Manual. When streaming, Consensys can also send data to Lab Streaming Layer, which records it alongside other LSL devices.

8.4. How do I convert the Unix timestamps in my export to a date and time?

Applies to: Shimmer3, Shimmer3R, data exported from Consensys

By default, the first column of a Consensys export is Unix time in milliseconds since 00:00:00 UTC on 1 January 1970, for example 1761654125125.0. To get the date and time:

• Excel: =A2/86400000 + DATE(1970,1,1), then format the cell as yyyy-mm-dd hh:mm:ss.000. The result is UTC; for local time, add your offset from UTC in hours divided by 24, for example + 1/24.
• MATLAB: datetime(t, 'ConvertFrom', 'epochtime', 'TicksPerSecond', 1000, 'TimeZone', 'UTC'), where t is the timestamp column. Set the TimeZone property of the result to see local time.
• Python (pandas): pd.to_datetime(t, unit="ms", utc=True), then .dt.tz_convert(...) for local time.

You can also choose Formatted Local as the Timestamp Format when you export, and Consensys writes the local date and time for you. See The timestamp column in the Consensys User Guide.

9. Sensors and data

9.1. What is the highest sampling rate?

Applies to: Shimmer3, Shimmer3R

The firmware accepts sampling rates up to 4096 Hz, but how high you can go without losing samples depends on how many sensors are enabled and, when streaming, on the PC’s or phone’s Bluetooth adapter. The more sensors, the lower the rate at which samples start to be lost. Each sensor guide recommends rates for the signals it measures.

9.2. Can I get the raw sensor data?

Applies to: Shimmer3, Shimmer3R

Yes. Consensys exports both uncalibrated (raw, unfiltered) and calibrated data, and the Shimmer APIs and instrument drivers give access to the raw data as well.

9.3. Is there sample data I can look at?

Applies to: Shimmer3, Shimmer3R

Yes. Consensys includes sample datasets in MANAGE DATA, which you can export to the format you want, and sample data for each sensor is on the documentation pages.

9.4. How is orientation (quaternion) data calculated?

Applies to: Shimmer3, Shimmer3R

From the accelerometer (low-noise or wide-range), the gyroscope and the magnetometer, with the MARG algorithm of Madgwick, Harrison and Vaidyanathan, Estimation of IMU and MARG orientation using a gradient descent algorithm (IEEE ICORR 2011). It is available in ConsensysPRO (the 9DoF to Quaternion algorithm) and in the Shimmer APIs and instrument drivers. There is no filter against magnetic disturbance, so keep the Shimmer away from metal and magnetic fields.

9.5. How many analogue inputs does a Shimmer have?

Applies to: Shimmer3, Shimmer3R

Seven: three on the external connector and four on the internal expansion connector, which the PROTO3 boards use. Shimmer3R names them differently, and has no internal expansion connector: its PROTO3 Deluxe is a single unified board. See Analogue channel names in the User Manual.

9.6. Why does a sensor give readings outside its range?

Applies to: Shimmer3, Shimmer3R, accelerometers, gyroscope and magnetometer

The range you choose (for example ±8 g or ±500 dps) is the range over which the sensor is specified to be accurate. When the motion or field goes beyond it, the sensor can still give readings a little past the range you set, but those readings are not accurate. At the very end of its scale the sensor stops at its largest value (see 7.2).

If your readings reach or pass the range, choose a wider range and record again.

10. Hardware and development

10.1. Is a Shimmer waterproof?

Applies to: Shimmer3, Shimmer3R

No. Never submerge it, or soak it with fluid, in use or when cleaning it. See Maintenance in the User Manual.

10.2. Is a Shimmer a medical device?

Applies to: Shimmer3, Shimmer3R

No. Shimmer3 and Shimmer3R are research devices, not medical devices, and must not be used for diagnosis. See Intended Use and Safety in the User Manual.

10.3. Can I write my own software for a Shimmer?

Applies to: Shimmer3, Shimmer3R

Yes. There are APIs for Java and Android, C# and Python, and instrument drivers for MATLAB and LabVIEW. See Software Development in the User Manual. The firmware is open source too: see Firmware Development in the same manual.

10.4. Can I fit two expansion boards, or design my own?

Applies to: Shimmer3, Shimmer3R

A Shimmer3 IMU has an internal expansion connector as well as the external one, so it can take one board on each at the same time, for example a PROTO3 Mini inside and the External Expansion Board outside. On a PROTO3 Deluxe, the prototyping board itself uses the internal connector. The Shimmer3 ExG, GSR+ and Bridge Amplifier+ are unified boards with no internal connector, and so is every Shimmer3R: they take only an external board.

You can design your own board for the external connector; its pin assignments are in the Shimmer3/3R Hardware Developer Reference.