Connecting and configuring sensors

This guide covers connecting sensors to a BODAQS logger and configuring the logger to read the sensor correctly.

The inputs on a BODAQS logger are general purpose - this means flexibility, but it also means some simple configuration is necessary when you first set up the logger, or when you want to attach additional sensors.

Plugs that look the same but aren't

BODAQS loggers use the same physical connector type to do many jobs. All the plugs on an A8 logger have the same 6-pin design, but there are three different configurations: one for analog connectors, one for I2C and one for UART and the bar switch. Ideally, all of these connector types would be unique but I haven’t been able to achieve that on a tight budget. It is recommended you color-code each male and female connector pair. Nail polish works well for this.

What ‘Configuring’ Means

Configuring a sensor means telling the logger:

• what type of sensor it is;
• where it is connected, such as AIN0, I2C1 address 54, or UART0;
• what the sensor is measuring, (‘signal semantics’) so downstream analysis tools know what to do with its output
• how to translate the raw sensor output into real-world measurements (calibration information)
• for some sensors, additional settings particular to the type of sensor.

Currently BODAQS loggers support the following sensor types:

Sensor type	Physical connection	Typical use
Analog Potentiometer	Analog input	Linear potentiometers for suspension travel.
AS5600 Angle (I2C)	I2C	Measurement of suspension linkage rotation for calculating rear wheel movement
AS5048B Angle (I2C)	I2C	Linkage rotation, higher-resolution single-turn rotary angle measurement.
DAN-F10N GPS (UART)	UART	On-logger GPS position, speed, and heading.
AS5600 String Pot (I2C)	I2C	Multi-turn AS5600-based string potentiometer, digitally read.
AS5600 String Pot (Analog)	Analog input	AS5600-based string potentiometer, read via analog.

Configuration information lives in a file on the SD card inside your logger. Normally you change it by connecting to the logger via WiFi.

As well as sensors, BODAQS loggers have an optional handlebar switch with an LED that can be used to start and stop logging and provide visual confirmation that logging is running. The switch does not require configuration: it just plugs in.\

Restart after structural changes

Adding a sensor, deleting a sensor, or changing a sensor’s type can be saved immediately, but will not take effect until the logger is re-started. Other sensor configuration changes are effective immediately on save.

Analog Sensors

Analog sensors use three logical wires:

Sensor wire	Connects to	Notes
+, VCC, excitation	Logger sensor power	Use the logger’s sensor supply, labelled ‘+3V0’ on A8 loggers and ‘+3V3’ on Prototype F loggers.
-, GND, 0V	Logger ground	Use the logger’s Ground, labelled ‘GND’.
signal, out, wiper	One analog input	Analog inputs are labelled ‘A0’ or ‘AIN0’, ‘A1’ or ‘AIN1’ etc.

See Sensor Overview to locate these pins on the logger. See Wiring and Connector Tips for practical wiring advice.

Analog Potentiometer

Use Analog Potentiometer configuration for ordinary three-wire linear potentiometers, often used as fork and shock displacement sensors. Connect each analog potentiometer per the table above. Multiple potentiometers can connect to the same logger + and - pins, but each one must have its own analog input.

+ and - wires can be swapped

It does not strictly matter which way around the + and - connections are wired: in one arrangement the sensor wil give maximum output at maximum travel; in the other, maximum output at minimum travel. Either is OK: the firmware infers polarity when range calibration is done.

Choose sensible sensor travel

The potentiometer must have more mechanical travel than the part it is measuring. Do not rely on the sensor’s internal end stops to limit suspension movement.

Analog potentiometer configuration

Connect to the logger configuration web interface and navigate to the Sensors page, as described in the User Guide

Add a new sensor of type Analog Potentiometer. Give it a helpful name, for example front_shock or rear_shock.

Click ‘Edit’ to edit the sensor configuration.

Set configuration options for the sensor:

1. Set Analog input to the AIN where the signal wire is connected.
2. Set Output mode to LINEAR. Enable Include raw column.
3. Measure the actual travel of the potentiometer. This is usually a few mm longer than the nominal travel. Set Sensor full travel (mm) to the measured value. potentiometer.
4. Set Installed range to the maximum travel of the thing you are measuring (usually a fork or shock). Note that ‘installed range’ does not directly affect the measurements made by the logger, but is needed if you want to use the logger’s Sag Helper.
5. Set the usage metadata. The primary quantity for analog pots is always ‘disp’ (they measure displacement). Set end to front or rear. Primary domain should usually be suspension, even for the front wheel (BODAQS considers all wheel travel to be vertical travel, so front suspension travel and wheel travel aren’t the same).
6. Leave the calibration data unchanged. Calibration is done through the logger and these values are set automatically.

Save the sensor when you are finished.

Analog potentiometer calibration and testing

There are two different calibration processes for an analog potentiometer: range calibration and zeroing. Both processes are completed on the logger. Instructions for calibration are here

Note that the order you read the end points matters for range calibration. The first reading must be the ‘zero travel’ end of the range. In most setups, this will be with the potentiometer fully extended. The second reading must be the ‘full travel’ end, usually with the potentiometer fully compressed. This matters because the logger uses the information to infer whether sensor output increases or decreases with travel.

Zeroing sensors on the bike is not strictly necessary since the software can guess zero from the minimum travel seen. However, I recommend zeroing. It’s super reliable and takes less than 30 seconds. Make sure the suspension is at full extension when zeroing: forks especially don’t always rest at fll extension.

Open the Sag Helper and switch to percentage mode. Sit on the bike and confirm that the sag percentages look about right.

AS5600 String Pot (Analog)

This sensor configuration is intended for use with the BODAQS string potentiometer design, a multi-turn string pot using an AS5600 magnetic encoder. At the time of writing the design is still in testing and has not been published.

AS5600 chips can be read either as I2C devices or as analog devices. This section covers configuration as an analog device.

Use I2C where possible

It is generally preferable to use AS5600 sensors in I2C mode since it provides access to all the chip’s on-board settings. Use analog only if you have a particular reason (e.g. you have spare analog inputs and have address-conflict issues).

BODAQS A8 logger only

It is not recommended that you run string pots in analog mode on Prototype F loggers due to limitations of the ESP32’s on-board ADCs.

Wiring is generally the same as for other analog devices, but with some additional caveats:

• The general rule that + and - can be reversed for analog devices does not apply here. An AS5600 is fundamentally a digital device, even if it can emulate an analog one.
• The AS5600’s GPO pin must be connected to + when in analog mode. -The AS5600’s DIR pin must be connected to either + or ’-’ (not left floating). In analog mode it’s generally easiest to tie it to +.

String potentiometer configuration (analog)

Connect to the logger configuration web interface and navigate to the Sensors page, as described in the User Guide Add a new sensor of type AS5600 string pot (analog). Give it a helpful name, for example front_shock or rear_shock. Click ‘Edit’ to edit the sensor configuration.

Set configuration options for the sensor:

1. Set Analog input to the AIN where the signal wire is connected.
2. Set Output mode to LINEAR. Enable Include raw column.
3. Measure the actual travel of the potentiometer. Set Sensor full travel (mm) to the measured value.
4. Set Installed range to the maximum travel of the thing you are measuring (usually a fork or shock). Note that ‘installed range’ does not directly affect the measurements made by the logger, but is needed if you want to use the logger’s Sag Helper.
5. Set the usage metadata. The primary quantity for string pots is always ‘disp’ (they measure displacement). Set end to front or rear. Primary domain should usually be suspension, even for the front wheel (BODAQS considers all wheel travel to be vertical travel, so front suspension travel and wheel travel aren’t the same).
6. Leave the calibration data unchanged. Calibration is done through the logger and these values are set automatically.
7. Leave the ‘wrapping’ data unchanged.

Save the sensor when you are finished.

String potentiometer calibration and testing (analog)

Use the same calibration and testing procedure as for an analog potentiometer.

Move string pot smoothly during range calibration

Move the string pot smoothly between zero and max during range calibration. This is important because the logger counts the turns of the encoder during calibration. Start with the pot at full extension and slowly let it retrct.

I2C Sensors

I2C sensors use four wires:

Sensor wire	Connects to
VCC	Logger 3.3 V
GND	Logger Ground
SDA	Logger SDA for the chosen bus
SCL	Logger SCL for the chosen bus

BODAQS loggers have two independent I2C buses, numbered 0 and 1. Each bus can have multiple I2C devices connected to it. Every device on the same I2C bus needs a unique address.

See Sensor Overview to locate these pins on the logger. See Wiring and Connector Tips for practical wiring advice.

AS5600 address conflict

AS5600 sensors normally use I2C address (hexadecimal)0x36, which the web UI stores as decimal 54. This conflicts with the logger’s battery ‘fuel gauge’, which also uses 0x36 on the I2C0 bus. AS5600 sensors need to be used on I2C1, connected via an address translator, or used in analog mode on an analog input.

AS5600 Angle Sensor

This sensor configuration is intended for use with AS5600 magnetic encoders used to measure an angle of less than one full turn. A common application is measuring the rotation of a rear suspension linkage in order to calculate wheel travel.

AS5600 bit count

The AS5600 is a 12-bit sensor, meaning it produces 4096 discrete outputs over a full cycle. For measuring linkages with a relatively small rotation, such as Santa Cruz VPP top linkages, consider a higher bit count encoder like the AS5048B.

Wiring is generally the same as for other I2C devices. The AS5600’s DIR pin must be connected to either + or ’-’ (not left floating).

AS5600 angle sensor configuration

Connect to the logger configuration web interface and navigate to the Sensors page, as described in the User Guide Add a new sensor of type AS5600 angle (I2C). Give it a helpful name, for example front_shock or rear_shock. Click ‘Edit’ to edit the sensor configuration.

Set configuration options for the sensor:

1. Set I2C bus. Normally for AS5600 sensors this will be 1 to avoid address conflict with the logger’s fuel gauge on I2C0. Leave I2C address unchanged.
2. Set Output mode to LINEAR. Enable Include raw column.
3. Set Installed range to the maximum rotational travel of the thing you are measuring (usually a linkage). Note that ‘installed range’ does not directly affect the measurements made by the logger, but is needed if you want to use the logger’s Sag Helper.
4. Set the usage metadata. The primary quantity for rotary sensors is always ‘ang_disp’ (they measure angular displacement). Set end to front or rear. Primary domain should usually be suspension.
5. Leave the calibration data unchanged. Calibration is done through the logger and these values are set automatically.
6. Generally leave the ‘other’ data unchanged at its default values.

Save the sensor when you are finished.

AS5600 angle sensor calibration and testing

AS5600 angle sensors require zeroing. The process is completed on the logger. Instructions for zeroing are here

Zeroing required for angle sensors

Unlike analog pots, the zeroing procedure is strictly required for angle sensors to ensure the logger can deal with sensor zero-crossings.

Open the Sag Helper and switch to percentage mode. Sit on the bike and confirm that the sag percentages look about right.

AS5048B Angle Sensor

This sensor configuration is intended for use with AS5048B magnetic encoders used to measure an angle of less than one full turn. A common application is measuring the rotation of a rear suspension linkage in order to calculate wheel travel.

AS5048B vs AS5600

The AS5048B is a 14-bit I2C magnetic encoder that can be configured with one of four I2C addresses. The most convenient way to buy one is as a dev board from a major electronics supplier. Use these if you are measuring small angles or would have address conflict issues with an AS5600.

The AS5600 is a 12-bit sensor with a fixed I2C address. It can emulate an analog sensor. It is available on a breakout board for a couple of dollars from AliExpress. If you are running a single rotary sensor and are measuring over a reasonable range of rotation, then consider savign your money and using one. But be warned: they are often supplied with very low quality magnets. You should source a diametric magnet separately from a reputable supplier if you buy an AliExpress AS5600.

In addition to wiring 3V3, GND, SCL and SDA to their matching inputs on the logger:

• The AS5048’s 3V3 and 5V pins must be connected together
• The A1 and A2 pins must each be connected either to 3V3 or GND, with the combination chosen determining the device’s I2C address.

AS5048B angle sensor configuration

Connect to the logger configuration web interface and navigate to the Sensors page, as described in the User Guide Add a new sensor of type AS5048B angle (I2C). Give it a helpful name, for example front_shock or rear_shock. Click ‘Edit’ to edit the sensor configuration.

Set configuration options for the sensor:

1. Set I2C bus and I2C address. Choose the bus you are going to connect the sensor to. Choose the address based on how you have wired pins A1 and A2 on the sensor.
2. Set Output mode to LINEAR. Enable Include raw column.
3. Set Installed range to the maximum rotational travel of the thing you are measuring (usually a linkage). Note that ‘installed range’ does not directly affect the measurements made by the logger, but is needed if you want to use the logger’s Sag Helper.
4. Set the usage metadata. The primary quantity for rotary sensors is always ‘ang_disp’ (they measure angular displacement). Set end to front or rear. Primary domain should usually be suspension.
5. Leave the calibration data unchanged. Calibration is done through the logger and these values are set automatically.
6. Generally leave the ‘other’ data unchanged at its default values.

Save the sensor when you are finished.

AS5048B angle sensor calibration and testing

Use the same calibration and testing procedure as for an AS5600 angle sensor.

AS5600 String Pot (I2C)

This sensor configuration is intended for use with the BODAQS string potentiometer design, a multi-turn string pot using an AS5600 magnetic encoder. At the time of writing the design is still in testing and has not been published.

AS5600 chips can be read either as I2C devices or as analog devices. This section covers configuration as an I2C device.

Wiring is generally the same as for other I2C devices. The AS5600’s DIR pin must be connected to either + or ’-’ (not left floating).

String potentiometer configuration (I2C)

Connect to the logger configuration web interface and navigate to the Sensors page, as described in the User Guide Add a new sensor of type AS5600 string pot (I2C). Give it a helpful name, for example front_shock or rear_shock. Click ‘Edit’ to edit the sensor configuration.

Set configuration options for the sensor:

1. Set I2C bus. Normally for AS5600 sensors this will be 1 to avoid address conflict with the logger’s fuel gauge on I2C0. Leave I2C address unchanged.
2. Set Output mode to LINEAR. Enable Include raw column.
3. Measure the actual travel of the potentiometer. Set Sensor full travel (mm) to the measured value.
4. Set Installed range to the maximum travel of the thing you are measuring (usually a fork or shock). Note that ‘installed range’ does not directly affect the measurements made by the logger, but is needed if you want to use the logger’s Sag Helper.
5. Set the usage metadata. The primary quantity for string pots is always ‘disp’ (they measure displacement). Set end to front or rear. Primary domain should usually be suspension, even for the front wheel (BODAQS considers all wheel travel to be vertical travel, so front suspension travel and wheel travel aren’t the same).
6. Leave the calibration and wrapping data unchanged. Calibration is done through the logger and these values are set automatically.
7. Leave the ‘async_rate_hz’ data unchanged.

Save the sensor when you are finished.

String potentiometer calibration and testing (I2C)

Use the same calibration and testing procedure as for an analog potentiometer.

Move string pot smoothly during range calibration

Move the string pot smoothly between zero and max during range calibration. This is important because the logger counts the turns of the encoder during calibration. Start with the pot at full extension and slowly let it retrct.

UART sensors

UART sensors use four logical wires:

Logger wire	Connects to sensor	Notes
3.3V	VCC
GND	GND
TX	RX	UART transmit and receive cross over.
RX	TX	UART transmit and receive cross over.

UART is crossed

Unlike power, ground, analog signal, SDA, or SCL, UART TX and RX are not connected like-for-like. Logger TX goes to sensor RX, and logger RX goes to sensor TX.

DAN-F10N GPS (UART)

Use the DAN-F10N GPS (UART) sensor type for an external u-blox based GPS module connected to the logger UART.

Connect:

GPS pin	Logger connection
VCC	3.3 V
GND	Ground
TX	Logger RX
RX	Logger TX

DAN-F10N GPS configuration

Connect to the logger configuration web interface and navigate to the Sensors page, as described in the User Guide Add a new sensor of type DAN-F10N GPS (UART). Give it a helpful name, like ‘GPS’. Click ‘Edit’ to edit the sensor configuration.

Set configuration options for the sensor:

1. Leave the UART_port set to 0. BODAQS loggers only have one UART connection.
2. Leave the baud rate at 38400.
3. Set update_rate_hz. This is the rate at which the GPS will update. 10hz (10 samples per second) is the maximum supported by the DAN-F10N GPS module.
4. Leave the remaining settings unchanged.

Save the sensor when you are finished.

DAN-F10N GPS testing

The GPS module does not require any calibration. After a GPS sensor is configured (and the logger restarted) tts status appears on the OLED idle screen:

• GPS means the logger has a usable fix.
• ..... means the receiver is present and acquiring.
• NOGPS means the receiver is absent, in error, muted, or not producing usable data.

While the web interface or upload mode is active, GPS acquisition will be deferred. After configuration, turn Wi-Fi off or restart the logger and give the receiver a clear sky view before judging fix performance.