SY021-PCB Datasheet

Overview

The Kallisto® SY021-PCB is a standalone sensor platform module based on the Nordic Semiconductor nRF52840 SoC. It combines six sensor ICs, Bluetooth LE, flash memory, a real-time clock and battery power management. The module can operate independently or be integrated into a carrier board using its bottom LGA pads. A separate extension connector provides access to shared sensor interfaces and additional I/O signals.

General Information

Item	Description
Product	Kallisto® SY021-PCB
Hardware design	v1.5
Product type	Standalone sensor platform module
SoC	Nordic Semiconductor nRF52840

Board views

Top view	Bottom view

Features

• SoC
  • nRF52840 with Bluetooth LE and an on-board antenna.
• Sensors
  • Acceleration, gyroscope, magnetic field and high-frequency vibration sensing.
  • Temperature, relative humidity, pressure and VOC values.
  • Optical sensing and a digital MEMS microphone.
• Peripherals
  • 1 Gbit (128 MiB) external flash memory and a real-time clock.
  • Four low-side transistor outputs, a user LED and a reset button.
• Connectors and power
  • Bottom LGA pads for carrier-board integration.
  • 10-pin extension connector and USB-C connector.
  • Battery connector, LiPo charging and Qi receiver circuitry for an external coil.

Programming & software support

The module is supplied with Kallisto® firmware for sensor configuration and data acquisition over Bluetooth LE. The Web Toolbox and the Android and iOS mobile apps provide access to the module. See Quick-Start for the initial connection and Ecosystem for software tools. Firmware updates for the platform module are available through the firmware update page.

Integrated Sensors

Component	Function	Interface	Key parameters
BMI270	3-axis accelerometer 3-axis gyroscope	SPI1	Acceleration: ±2/4/8/16 g, output data rate up to 1.6 kHz. Angular velocity: ±125/250/500/1000/2000 °/s, output data rate up to 6.4 kHz.
LIS2MDL	3-axis magnetometer	SPI1	±50 gauss; 16-bit output; continuous-mode output data rates of 10, 20, 50 or 100 Hz.
KX134-1211	3-axis accelerometer for vibration sensing	SPI3	±8/16/32/64 g; 16-bit output; output data rate up to 25.6 kHz.
BME680	Temperature, humidity, pressure and gas sensor	I²C	Temperature: −40 to +85 °C. Relative humidity: 0–100 % RH. Pressure: 300–1100 hPa. VOC values: software processing with the Bosch BSEC library.
OPT3002	Light-to-digital sensor	I²C	Spectral range: 300–1000 nm. Measurement levels: 1.2 nW/cm² to 10 mW/cm² at 505 nm. Integration time: 100 or 800 ms.
SPK0641HT4H-1	Digital MEMS microphone	PDM	Mono PDM output. Typical sensitivity: −26 dBFS at 94 dB SPL and 1 kHz in low-power mode.

The key parameters describe the capabilities of the individual sensor ICs, rather than firmware sampling or Bluetooth streaming rates. Available settings and data rates depend on the firmware and its configuration.

Measurement characteristics

The following values describe the sensor ICs, not the accuracy of the complete board or the output rate of Kallisto® firmware. Available ranges, rates and processed outputs depend on firmware configuration. Typical values are marked typ.; accuracy figures apply under the stated conditions.

Measurement overview

Measurand	Component	Range / response
Acceleration, x/y/z	BMI270	±2 / ±4 / ±8 / ±16 g
Angular velocity, x/y/z	BMI270	±125 / ±250 / ±500 / ±1,000 / ±2,000 °/s
Magnetic field, x/y/z	LIS2MDL	Nominal ±50 gauss
Vibration acceleration, x/y/z	KX134-1211	±8 / ±16 / ±32 / ±64 g
Temperature	BME680	−40 to +85 °C
Relative humidity	BME680	0–100 %RH, non-condensing
Ambient pressure	BME680	300–1,100 hPa
Gas resistance / VOC response	BME680	Resistance in Ω; no selective gas-concentration range
IAQ (derived)	BME680 + BSEC	0–500 air-quality index
eCO₂ (derived)	BME680 + BSEC	CO₂-equivalent in ppm
bVOC (derived)	BME680 + BSEC	Breath-VOC equivalent in ppm
Optical irradiance	OPT3002	1.2 nW/cm² to 10.064 mW/cm² at 505 nm; spectral response 300–1,000 nm
Raw audio	SPK0641HT4H-1	20 Hz–20 kHz response; 120 dB SPL overload typ. at 10% THD, 1 kHz

IAQ, eCO₂ and bVOC require the Bosch BSEC library. These values are calculated from the BME680 measurements; they are not direct VOC or CO₂ concentration measurements. Availability depends on the firmware's BSEC integration. See the BME680 details below.

Resolution, accuracy and output formats

BMI270 — acceleration and angular velocity

Source: BMI270 datasheet.

Parameter	Acceleration	Angular velocity
Hardware output data rate	Normal: 12.5–1,600 Hz; low power: 0.78–400 Hz	Normal/performance: 25–6,400 Hz; low power: 25–100 Hz
Sensitivity, in ascending range order	16,384 / 8,192 / 4,096 / 2,048 LSB/g	262.144 / 131.072 / 65.536 / 32.768 / 16.384 LSB/(°/s)
Gain error	±0.4% at ±8 g	±2%; ±0.4% after component retrimming (CRT)
Zero offset at 25 °C	±20 mg	±0.5 °/s
Output	16 bits/axis	16 bits/axis

LIS2MDL — magnetic field

Source: LIS2MDL datasheet.

Parameter	Value / condition
Hardware output data rate	10 / 20 / 50 / 100 Hz
Digital range	±49.152 gauss; nominal ±50 gauss
Sensitivity	1.5 mgauss/LSB (0.15 µT/LSB)
Sensitivity tolerance	±7%
Offset with offset cancellation	±60 mgauss at 25 °C, 2.5 V
Output	16 bits/axis

The offset test voltage differs from the board's nominal 1.8 V supply.

KX134-1211 — vibration acceleration

Source: KX134-1211 specifications, Rev. 4.0, tables 1–2. Unless stated otherwise, these IC specifications apply at 2.5 V and 25 °C.

Parameter	Value / condition
Measurement ranges	±8 / ±16 / ±32 / ±64 g
Output data rate	Up to 25.6 kHz
Sensitivity, 16-bit mode, in ascending range order	4,096 / 2,048 / 1,024 / 512 counts/g typ.
Sensitivity min.–max., same range order	3,768–4,424 / 1,884–2,212 / 942–1,106 / 471–553 counts/g; tolerance at ±1 g stimulus
Zero-g offset	±75 mg typ.; ±175 mg max.
Sensitivity temperature variation	0.01%/°C typ.
Zero-g offset temperature variation	0.5 mg/°C typ.
Non-linearity	0.6% of full scale typ.
Cross-axis sensitivity	2% typ.
Mechanical −3 dB bandwidth	x: 8.2 kHz; y: 8.5 kHz; z: 5.6 kHz typ., at 25.6 kHz ODR and LPRO = 1
Output	16 bits/axis; optional 8-bit buffer mode

Effective bandwidth depends on the output data rate and filter settings. The manufacturer's 2.5 V test condition differs from the module's nominal 1.8 V sensor supply; these figures are not module-level accuracy guarantees.

BME680 — temperature, humidity, pressure and gas response

Source: BME680 datasheet.

Measurand	Resolution	Accuracy / condition	Raw output
Temperature	0.01 °C API step	±0.5 °C at 25 °C; ±1 °C over 0–65 °C	20-bit register; 16–20 useful bits
Humidity	0.008 %RH	±3 %RH at 25 °C, 20–80 %RH, including hysteresis	16 bits
Pressure	0.18 Pa at highest oversampling	Absolute ±0.6 hPa over 0–65 °C; relative ±0.12 hPa over 700–1,100 hPa, 25–40 °C, constant RH	20-bit register; 16–20 useful bits
Gas resistance	0.08% relative resolution typ.	No universal VOC concentration accuracy	10-bit ADC + 4-bit range code

Derived outputs — Bosch BSEC library required

Output	Range / meaning	Resolution / accuracy	Format
IAQ	0–500 air-quality index	1 index point; algorithm and test-condition dependent	BSEC software output
eCO₂	CO₂-equivalent in ppm	Algorithm-dependent; no direct CO₂ measurement accuracy	BSEC software output
bVOC	Breath-VOC equivalent in ppm	Algorithm-dependent; no universal concentration accuracy	BSEC software output

These outputs require the Bosch BSEC library integrated into the firmware. They are calculated from sensor measurements, not direct VOC or CO₂ concentration measurements. LP updates every 3 s; ULP every 300 s. Availability depends on the BSEC version and firmware configuration.

Temperature, pressure and humidity share a conversion cycle. Timing depends on enabled measurements, oversampling and heater settings; useful temperature and pressure bits depend on oversampling. The temperature reading includes PCB temperature and sensor self-heating.

Measurement timing

The BME680 uses host-triggered measurements; conversion time depends on oversampling and heater duration. BSEC defines the following update intervals (BME680 datasheet, section 4.1, table 17):

BSEC mode	Temperature, pressure and humidity	Gas / IAQ update interval
Ultra-low power (ULP)	300 s	300 s
Quick ultra-low power (q-ULP)	3 s	300 s
Low power (LP)	3 s	3 s
Continuous (CONT), testing only	1 s	1 s

CONT is intended for short-term testing. These intervals describe BSEC operating modes, not a guaranteed board output rate. Firmware must follow the scheduling of its BSEC version and configuration; a 10 s interval is not one of the modes listed in the datasheet.

OPT3002 — optical irradiance

Source: OPT3002 datasheet.

Parameter	Value / condition
Resolution	1.2 × 2ᴱ nW/cm²/LSB; exponent E = 0–11
Integration time	100 / 800 ms; approximately 9.7 / 1.25 samples/s
Linearity	2% above 5,000 nW/cm²; 5% below
Range matching	0.2% typ.
Output	12-bit mantissa + 4-bit exponent; 23-bit dynamic range

The finest resolution requires 800 ms integration. Automatic range changes and conversion timing affect the effective rate.

SPK0641HT4H-1 — raw audio

Source: SPK0641HT4H-1 datasheet.

Parameter	Value / condition
PDM clock frequency	Performance: 1–4.8 MHz; low power: 0.35–0.8 MHz
Sensitivity	−26 dBFS at 94 dB SPL, 1 kHz
Sensitivity tolerance	±1 dB
Signal-to-noise ratio	64.5 dB(A) typ., performance mode
Output	1-bit PDM

Sensitivity conditions: 1.8 V supply, 768 kHz PDM clock, 23 ±2 °C and 55 ±20 % relative humidity. PDM clock frequency is not the PCM sample rate. Decimation, PCM sample rate and word length are set by firmware.

SoC and peripherals

Component	Function
nRF52840	64 MHz Arm Cortex-M4F SoC with Bluetooth LE, 1 MB internal flash and 256 KB RAM.
W25Q01NWZEIM	1 Gbit (128 MiB) external serial flash on SPI2, including the additional Quad SPI data lines.
PCF85263ATL	I²C real-time clock with battery backup. Its interrupt output is connected to SHPHLD.
nPM1100	Power management, battery charging, system power path and the 1.8 V buck supply.
BQ51013BRHL	Qi wireless-power receiver and USB input-source control.
CSD13381F4	Four low-side switching outputs EXT0–EXT3 on the LGA pads.

System Block Diagram

SPI1, I²C and PDM signals are shared with on-board devices. In particular, PDM_DATA is driven by the on-board microphone; an external device must not drive the same data slot. The low-side outputs switch a load towards ground and do not supply a positive output voltage.

Technical Data

Mechanical Parameters

Parameter	Value
Board construction	Bottom LGA pads with top-side component assembly
PCB outline, length × width × height	54 mm × 22 mm × 5 mm
Mounting holes	Three holes, Ø2.2 mm
Battery connector	Molex 78171-0003, 3 pins
Extension connector	Molex 504050-1091, 10 pins
Radio antenna	On-board chip antenna
User controls	Reset button and user LED

LGA Pinout

The following drawing is a top view of the PCB with the bottom LGA pads projected onto it. Signal directions in the table are relative to the module. Logic signals use the nominal 1.8 V domain unless another domain is listed.

Pad	Signal	Direction / type	Domain	Function / restrictions
1	EXT_UART_RX	Input	1.8 V logic	UART receive; shared with extension connector pin 10.
2	EXT_UART_TX	Output	1.8 V logic	UART transmit; shared with extension connector pin 9.
3	EXT_GPIO2	I/O	1.8 V logic	GPIO; shared with extension connector pin 8.
4	EXT_GPIO1	I/O	1.8 V logic	GPIO; shared with extension connector pin 7.
5	PDM_DATA	Input to SoC	1.8 V logic	Shared with the on-board microphone and extension connector pin 6.
6	PDM_CLK	Output	1.8 V logic	Shared microphone clock; extension connector pin 5.
7	SCL	I/O	1.8 V logic	Shared I²C clock; extension connector pin 4.
8	SDA	I/O	1.8 V logic	Shared I²C data; extension connector pin 3.
9	+1V8	Power output	1.8 V	Regulated module supply rail.
10	GND	Ground	Ground	Common ground.
11	SWDCLK	Debug	1.8 V logic	Reserved for programming/debugging; do not connect in application circuitry.
12	SWDIO	Debug	1.8 V logic	Reserved for programming/debugging; do not connect in application circuitry.
13	SWO	Debug	1.8 V logic	Reserved for programming/debugging; do not connect in application circuitry.
14	nRES	Input	1.8 V logic	Active-low system reset; shared with the reset button.
15	SPI1_MOSI	Output	1.8 V logic	Shared SPI1 controller data output.
16	SPI1_SCK	Output	1.8 V logic	Shared SPI1 clock.
17	SPI1_MISO	Input	1.8 V logic	Shared SPI1 controller data input.
18	QI_COIL2	Coil connection	Qi receiver input	Receiver-coil terminal 2.
19	QI_COIL1	Coil connection	Qi receiver input	Receiver-coil terminal 1.
20	+1V8	Power output	1.8 V	Same regulated rail as pad 9.
21	EXT0	Low-side output	Load circuit	Switched connection towards ground, channel 0.
22	EXT1	Low-side output	Load circuit	Switched connection towards ground, channel 1.
23	USB_P	I/O	USB	USB D+; shared with USB-C connector.
24	USB_N	I/O	USB	USB D−; shared with USB-C connector.
25	EXT2	Low-side output	Load circuit	Switched connection towards ground, channel 2.
26	EXT3	Low-side output	Load circuit	Switched connection towards ground, channel 3.
27	VSYS	Power output	System rail	PMIC system supply; shared with extension connector pin 2. Do not supply this pad externally.
28	+5V	Power input / shared rail	Nominal 5 V	Charger input rail, also supplied by the USB input switch or Qi receiver.
29	SHPHLD	Control input	PMIC; VBAT pull-up	Active-low wake input; shared with the RTC interrupt output.
30	GND	Ground	Ground	Common ground.
31	SHPACT	Control	1.8 V logic	Ship-mode activation; shared with an internal SoC output.
32	RESERVED	—	—	Do not connect.
33	ISET	Internal control output	1.8 V logic	PMIC input-current selection; not a general-purpose I/O.
34	GND	Ground	Ground	Common ground.
35	ADC1	Analog input	SoC analog input	Connected to nRF52840 AIN4 / P0.28.
36	ADC0	Analog input	SoC analog input	Connected to nRF52840 AIN0 / P0.02.
37	VBAT	Battery power	Battery rail	Battery positive; shared with battery connector pin 1.
38	BAT_NTC10K	Analog input	Battery-temperature circuit	Battery 10 kΩ NTC; shared with battery connector pin 2.
39	GND	Ground	Ground	Common ground; shared with battery connector pin 3.

Electrical Parameters

The nPM1100 generates the nominal 1.8 V rail for the SoC, sensors, memory and RTC main supply. VSYS is the separate system rail and follows the active power path; it is not the regulated 1.8 V output. The extension connector supplies VSYS, while the bottom LGA exposes both rails.

Board Power & Battery Charge

A 150 mAh or 500 mAh battery can be ordered together with the module. Other battery capacities can be ordered on request.

Supply path	Connection	Use
USB-C	USB-C connector	Module power and battery charging.
External 5 V	LGA pad 28 (+5V) and ground	Shared charger-input supply.
Battery	Battery connector or LGA pads 37–39	Module power without external input.
Qi	Receiver coil on LGA pads 18–19	Charger input via BQ51013B.

The module can operate from USB-C with or without a battery. The USB input switch and Qi receiver feed the common +5V rail upstream of the nPM1100. The BQ51013B selects the wired USB source when it is present. Its AD-EN output controls the USB input switch.

Current selection and source control

Signal / configuration	Function
ISET low	Nominal PMIC input-current limit: 100 mA. A pull-down establishes this state when the SoC does not drive the signal.
ISET high	Nominal PMIC input-current limit: 500 mA. Firmware must select this only when the connected source permits it.
ICHG configuration	Charger-current setting: 400 mA. Actual battery current also depends on the input-current limit, system load and thermal regulation.

ISET selects an input limit, not a guaranteed battery charge current.

Qi receiver coil

Connect the receiver coil to QI_COIL2 and QI_COIL1, LGA pads 18 and 19. The coil specified in the hardware design is the TDK WR222230-26M8-G. Its placement and coupling to the transmitter are part of the mechanical integration. The receiver coil can be ordered together with the module.

Battery Interface

A 150 mAh or 500 mAh battery is available as an option when ordering the module. Other battery capacities can be ordered on request.

Use a protected single-cell LiPo battery with a 10 kΩ temperature-sensing NTC. The battery must be suitable for the configured charging current. The battery connector is Molex 78171-0003; the same signals are available on the LGA pads.

Battery connector pin	Signal	LGA pad
1	VBAT — battery positive	37
2	Battery NTC	38
3	GND — battery negative	39

The RTC backup supply is connected to VBAT independently of the main 1.8 V rail.

Extension Interface

The 10-pin Molex Pico-Lock connector 504050-1091 exposes the signals below. Directions are relative to the module; digital signals use the nominal 1.8 V domain. The I²C and PDM connections share their on-board sensor buses.

Pin	Signal	Direction / type	Domain	Function
1	GND	Ground	Ground	Common ground.
2	VSYS	Power output	System rail	PMIC system supply; do not supply externally.
3	SDA	I/O	1.8 V logic	Shared I²C data.
4	SCL	I/O	1.8 V logic	Shared I²C clock.
5	PDM_CLK	Output	1.8 V logic	Shared microphone clock.
6	PDM_DATA	Input to SoC	1.8 V logic	Shared microphone data.
7	EXT_GPIO1	I/O	1.8 V logic	GPIO; also LGA pad 4.
8	EXT_GPIO2	I/O	1.8 V logic	GPIO; also LGA pad 3.
9	EXT_UART_TX	Output	1.8 V logic	UART transmit.
10	EXT_UART_RX	Input	1.8 V logic	UART receive.

Ship Mode Activation / Deactivation

Ship mode isolates the battery from the PMIC system power path for transport or storage. It does not disconnect the RTC backup supply from the battery.

Action	Conditions / signal
Enter ship mode	Remove external input power. Hold SHPACT high, at least 1.1 V, for at least 200 ms. Firmware can also drive the internally connected SHPACT signal.
Leave ship mode through SHPHLD	Hold SHPHLD low, at most 0.4 V, for at least 200 ms. The RTC interrupt shares this signal.
Leave ship mode through input power	Apply power to the PMIC input, for example through USB-C.

For development and programming support, contact support@sensry.de.