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232204 - EverTag Connectivity Module Base PCB Bat + Radar
Article Number 232204
Name EverTag Connectivity Module Base PCB Bat + Radar
Base PCB 232200 Base Std
Added Features Battery + PIR/Radar occupancy sensor
Status Not included in the first PCB iteration

Anchor-Only Variant

The 232204 is an anchor (Wirepas mesh node), not a gateway. It extends 232201 Base Bat with a PIR/Radar occupancy sensor. No WiFi gateway, no ESP32, no LTE board-to-board connector. This keeps the radar variant focused on presence detection in battery-backed anchor deployments.

Not in First PCB Iteration

This PCB variant is fully specified but is not included in the first PCB production run. The specification is provided here for future iterations.

1. Overview

The 232204 extends 232201 Base Bat with a PIR/Radar occupancy sensor. It does not include WiFi gateway or LTE extension capabilities. In Wirepas terms, combining radar with gateway options adds complexity without clear use cases; the 232204 targets battery-backed anchor deployments with local presence detection.

Key Features

  • Everything in 232201 Base Bat: PAN611, ST25DV04K NFC, LED1 (LED2 DNP), USB-C, service button, battery
  • PIR or Radar occupancy/presence sensor
  • No ESP32 WiFi module
  • No LTE board-to-board connector (no mount)

2. Block Diagram

graph TB
    subgraph power [Power Supply]
        VIN["5V Input from Power Base"] --> PPM["Power-Path Manager"]
        BAT["LiFePO4 Battery"] --> VPROT["Voltage Protection"]
        VPROT --> PPM
        PPM --> BUCK["TPS62160 Buck Converter"]
        BUCK --> RAIL["3.3V Rail"]

        PPM --> CHRG["MCP73123 Charger"]
        CHRG --> VPROT
    end

    subgraph mcu_block [MCU / Radio]
        PAN611["PAN611 - nRF54L15"]
    end

    subgraph sensor [Occupancy Sensor]
        PIR["PIR / Radar Sensor"]
    end

    subgraph nfc_block [NFC]
        ST25DV["ST25DV04K"]
        NFCANT["2-Layer Coil Antenna"]
    end

    subgraph indicators [UI]
        LED1["SK6812 #1 System LED"]
    end

    RAIL --> PAN611
    RAIL --> PIR

    PAN611 <-->|"SPI or UART or I2C"| PIR
    PAN611 -->|"I2C"| ST25DV
    ST25DV --> NFCANT
    PAN611 -->|"P0.01 data"| LED1

    PAN611 -.->|"Battery mgmt"| PPM

3. Schematics

3.1 Occupancy Sensor Interface (Multi-Option)

The sensor type is a customer-driven BOM decision. The PCB routes a 5-pin sensor interface to a footprint area near the enclosure front, supporting multiple sensor families via the same pin set:

Parameter Value
Interface Options SPI (radar), UART (radar), Analog + digital (PIR), I2C (shared)
Supply 3.3V
Detection Occupancy / presence (motion and/or static)
nRF54 Pins P1.11, P1.13, P1.14 (SAADC-capable), P1.08, P2.09, P1.03 (RADAR_EN)

Sensor Interface Pin Assignment

On 232204 (no gateway), P0.03/P0.04/P1.10 remain available; P1.08 and P2.09 were SPI CS and ACC INT2 on 230220, now available on Station boards. P1.11/P1.13/P1.14 are SAADC-capable and used for the sensor.

Pin SAADC Direction SPI Use (Radar) UART Use (Radar) Analog Use (PIR) Notes
P1.11 AIN4 Output SPI_CLK UART_TX (to sensor) -- Sensor CLK
P1.13 AIN6 Input SPI_MISO UART_RX (from sensor) Analog in (PIR signal) Sensor MISO
P1.14 AIN7 Output SPI_MOSI -- -- Sensor MOSI
P1.08 -- Output SPI_CS -- -- Sensor CS
P2.09 -- Input IRQ / data ready Presence out Digital out (comparator) Sensor IRQ
P1.03 -- Output RADAR_EN -- -- A121 ENABLE

Additionally, the I2C bus (P1.04/P1.05) is available as a shared bus with ST25DV04K for I2C-based sensors.

Option A: SPI Radar — Acconeer A121 (Default)

Pulsed coherent radar (60 GHz). Excellent static presence detection. SPI interface uses all 4 dedicated pins + IRQ + ENABLE. This is the default/recommended option. See Section 5.1 for the complete circuit specification.

Feature Value
Interface SPI (CLK, MISO, MOSI, CS) + IRQ + ENABLE
Detection Motion + static presence, 0--10m
Power ~30--80 mA active, duty-cyclable
RF coexistence 60 GHz -- zero concern with 2.4 GHz
Enclosure No IR window needed (radar penetrates plastic)
Dev effort Medium (SPI driver + algorithm tuning)
BOM ~$5--8 (module)

Integrated 24 GHz radar module with built-in signal processing. UART AT command interface.

Option C: Analog PIR

Bare dual-element pyroelectric sensor. Requires external analog frontend on the PCB.

Option D: I2C Sensor

Uses shared I2C bus (P1.04/P1.05) and P2.09 for IRQ.

4. Pin-Out (Delta)

Additional GPIO requirements beyond 232201 pin-out:

nRF54 Pins -- Occupancy Sensor

GPIO SAADC Function Direction Notes
P1.11 AIN4 SENSOR_CLK / TX Output SPI CLK or UART TX to sensor
P1.13 AIN6 SENSOR_MISO / RX / AIN Input SPI MISO or UART RX or analog PIR
P1.14 AIN7 SENSOR_MOSI Output SPI MOSI
P1.08 -- SENSOR_CS Output SPI CS
P2.09 -- SENSOR_IRQ Input IRQ / presence detect digital output
P1.03 -- RADAR_EN Output A121 ENABLE (HIGH = active, LOW = < 1 µA standby)

Multi-Option Sensor Interface

These 6 pins route to a common sensor footprint area. The BOM determines which sensor is populated. SPI radar uses all 6 pins (including RADAR_EN). UART radar uses P1.11 + P1.13 + P2.09. Analog PIR uses P1.13 (AIN6 for ADC) + P2.09. I2C sensors share the bus and use P2.09 for IRQ.

5. Component Selection (Delta)

5.1 Occupancy Sensor — Default: Acconeer A121 (SPI Radar)

The Acconeer A121 is the default/recommended occupancy sensor for BOM costing and first prototype builds. Other sensor options (UART radar, PIR, I2C) remain supported by the PCB layout -- see Section 3.1 for the full multi-option interface.

Parameter Value
Sensor IC Acconeer A121
Technology Pulsed coherent radar (PCR), 60 GHz
Package fcCSP, 5.5 × 5.2 × 0.88 mm, 0.5 mm pitch
Interface SPI (CLK, MISO, MOSI, CS) + ENABLE + INTERRUPT
Detection Motion + static presence, 0--10 m range
Power (1.8V) ~3 mA sleep, ~75 mA active (duty-cyclable)
Standby (EN=LOW) < 1 µA
RF band 60 GHz — zero coexistence concern with 2.4 GHz BLE/WiFi
Enclosure No IR window needed (60 GHz penetrates plastic enclosure)
Est. Price ~$5--8 (sensor module)
Datasheet Acconeer A121 Datasheet

A121 Complete Circuit

The A121 requires external support circuitry: a 1.8V LDO, a 24 MHz crystal, decoupling capacitors, and SPI connection to the nRF54L15 host MCU.

1.8V LDO Regulator (Sensor Power)
Parameter Value
IC TI LP5907MFX-1.8/NOPB
Package SOT-23-5
Input 3.3V main rail
Output 1.8V (A121 VRX, VTX, VDIG)
Max Current 250 mA (sufficient for A121 ~75 mA peak)
Noise 6.5 µVrms (ultra-low noise, critical for radar)
Est. Price ~$0.35 USD
24 MHz Crystal
Parameter Value
Frequency 24.000 MHz
Type AT-cut, fundamental mode
Load Cap Per A121 datasheet specification
Package 3215 or 2016 SMD
Tolerance ±10 ppm
SPI Connection to nRF54L15
A121 Pin nRF54 Pin Function Notes
SPI_CLK P1.11 SPI clock Keep trace short, ground-referenced
SPI_MISO P1.13 Data: A121 → MCU SAADC-capable pin (AIN6)
SPI_MOSI P1.14 Data: MCU → A121
SPI_CS P1.08 Chip select (active low)
INTERRUPT P2.09 Data ready / alert Rising edge interrupt
ENABLE P1.03 (RADAR_EN) Sensor power control HIGH = active, LOW = < 1 µA standby
VIO 3.3V rail I/O voltage reference Matches nRF54 I/O level

ENABLE Pin GPIO

The ENABLE pin allows firmware to completely shut down the A121 (< 1 µA). Connected to P1.03 (RADAR_EN) -- the NFC2 GPIO reserve pin, which is free on 232204 because the MCP73123 charger has only one STAT output (on P2.04) and does not need P1.03.

A121 PCB Design Notes
  • Ground plane: A121 requires a solid ground plane beneath the sensor. Minimum ground plane size per Acconeer recommendation: ≥20 × 20 mm.
  • Placement: Sensor faces the enclosure front (sensor window region). Keep away from heat sources (buck converter).
  • Radome distance: Target 2.5 mm, 5 mm, or 7.5 mm air gap between A121 antenna face and inner enclosure wall (optimum: m × λ₀/2 at 60 GHz). See 232506 Enclosure Design for full radome requirements.
  • SPI traces: Short, ground-referenced.
  • VIO: Connect to 3.3V rail (matches nRF54 I/O voltage).
  • No IR window: 60 GHz radar penetrates the plastic enclosure.
  • Conformal coating: If coating is applied over the A121, use thin layer (< 40 µm) with low permittivity and low loss. Many coatings are not well characterized at 60 GHz — verify performance by test.

6. PCB Design Notes (Delta)

6.1 Board Area

This variant adds the sensor footprint to the 232201 layout:

  • PAN611 module (with RF clearance zone)
  • Battery connector and charger circuit
  • PIR/Radar sensor (facing front of enclosure)

No ESP32 module, no LTE B2B connectors (no mount).

7. Test Points (Delta)

Additional test points beyond 232201:

TP # Signal Expected Value Notes
TP33 PIR_OUT Logic Sensor detection output

232204-Specific Tests

  • PIR/Radar sensor detection test (motion in front of enclosure)

8. Revision History

Revision Date Author Changes
Rev A TBD TBD Renamed from Base Full. Removed WiFi gateway, LTE B2B connector. Anchor-only variant.