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232203 - EverTag Connectivity Module Base PCB Bat + WIFI
Article Number 232203
Name EverTag Connectivity Module Base PCB Bat + WIFI
Base PCB 232200 Base Std
Added Features LiFePO4 battery backup + ESP32-C5 WiFi gateway
Status Active

Combined Delta Document

This PCB combines the battery feature from 232201 and the WiFi feature from 232202 on a single board. For full details on each feature, refer to the individual delta documents. This document covers only the integration-specific aspects. Both LED1 (system) and LED2 (gateway) are populated. Service button, USB-C, TC2030-CTX-NL J1 (nRF54, with 470Ω series R), and TC2030 J2 (ESP32, with auto-reset circuit and 470Ω series R) are inherited from 232200/232202.

1. Overview

The 232203 is the combined battery + WiFi variant. It includes all features from both the 232201 (battery backup) and 232202 (WiFi gateway), enabling the EverTag Station to function as a battery-backed Wirepas-to-WiFi gateway.

Key Features

  • Everything in 232200 Base Std: PAN611 (nRF54L15), ST25DV04K NFC, RGB LED, SWD
  • Everything in 232201 Base Bat: LiFePO4 battery, charger, power-path management
  • Everything in 232202 Base WIFI: ESP32-C5 WROOM, UART1 (Wirepas Dual-MCU API), coexistence

Integration-Specific Aspects

  • Combined power budget (battery must support both MCU and WiFi module)
  • Layout optimization for all three RF domains (Wirepas, WiFi, NFC) on a single PCB
  • Battery hold-up time is reduced when WiFi module is active

2. Block Diagram

graph TB
    subgraph power [Power Supply - Full]
        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 --> LDO["AP2112K WiFi LDO"]
        LDO --> WIFI_PWR["3.3V WiFi Rail"]

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

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

    subgraph wifi_block [WiFi Gateway Module]
        ESP32["ESP32-C5 WROOM"]
    end

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

    subgraph indicators [UI]
        LED1["SK6812 #1 System LED"]
        LED2["SK6812 #2 Telematics LED"]
    end

    RAIL --> PAN611
    WIFI_PWR --> ESP32
    PAN611 -->|"I2C"| ST25DV
    ST25DV --> NFCANT
    PAN611 -->|"P0.01 data"| LED1
    LED1 -->|"daisy-chain"| LED2

    PAN611 <-->|"UART1: Dual-MCU API"| ESP32
    ESP32 -->|"COEX REQUEST"| PAN611
    PAN611 -->|"COEX GRANT"| ESP32
    ESP32 -->|"READY"| PAN611

    PAN611 -.->|"Battery presence"| PPM
    PAN611 -.->|"Battery voltage ADC"| BAT

3. Power Budget

The combined variant has the highest power consumption of the active PCB variants. The battery hold-up time depends on the WiFi module operating state.

Estimated Current Consumption

Operating Mode nRF54 (PAN611) ESP32-C5 Total from Power-Path
Sleep (all radios off) TBD uA TBD uA TBD uA
Wirepas + WiFi idle TBD mA TBD mA TBD mA
Wirepas + WiFi active TX TBD mA ~300 mA peak TBD mA

Battery Hold-Up Time Estimate

Preliminary

These are preliminary estimates. Actual hold-up time depends on WiFi traffic pattern and Wirepas network load.

Mode Estimated Hold-Up Time
Wirepas + WiFi idle (connected) TBD (several hours)
Wirepas + WiFi continuous gateway TBD (reduced)

Full Gateway on Battery

The AP2112K WiFi LDO is fed from the power-path diode-OR output -- the same battery-backed node that feeds the TPS62160. When AC power is lost, both the nRF54 and ESP32 continue running on battery. The station remains a fully operational Wirepas gateway on battery: mesh traffic continues to be forwarded via WiFi.

This is essential because gateway nodes are traffic sinks in the Wirepas mesh. If the ESP32 (WiFi uplink) were powered off while the nRF54 remained visible as a gateway, other mesh nodes would continue routing data to it with nowhere to go -- creating a traffic black hole.

Battery life is shorter than anchor-only operation (hours rather than days), but maintaining the gateway link is the correct trade-off. Firmware monitors battery voltage (P1.06 / AIN2) and performs a graceful shutdown of both MCUs before the battery reaches the ESP32 brown-out threshold (~3.0V).

Design consideration: Firmware should monitor BAT_VOLTAGE (P1.06 / AIN2) and trigger an orderly shutdown (ESP32 WiFi disconnect → nRF54 Wirepas leave → power off) when battery voltage drops below a configurable threshold (e.g., 3.1V). This gives the mesh time to re-route traffic to another gateway before this node goes offline.

4. PCB Layout Integration Notes

Combining battery and WiFi features on a single board requires careful layout:

  • Component placement priority: PAN611 module and ESP32-C5 module should be placed first, with RF clearance zones maintained. Battery connector and charger circuit fill remaining space.
  • Ground plane management: maintain ESP32 ground stitching fence from 232202 design while also accommodating battery power-path components
  • Power routing: charger IC, power-path manager, TPS62160, and WiFi LDO all draw from the power-path output -- ensure adequate copper width for combined current (nRF54 + ESP32 peak ~400 mA)
  • Board area: this is the most populated variant -- verify all components fit within the enclosure PCB outline

5. Additional Pin-Out (Delta)

This variant combines pin-outs from both 232201 and 232202. No additional GPIOs are required beyond those defined in the individual delta documents.

Combined GPIO Summary

Function nRF54 GPIO ESP32-C5 GPIO Source Notes
BAT_PRESENT (PG) P2.03 -- 232201 MCP73123 PG (open-drain, 10k pull-up). LOW = AC on
BAT_VOLTAGE (ADC) P1.06 -- 232201 Battery voltage via resistor divider (SAADC AIN2)
CHARGE_STATUS P2.04 -- 232201 MCP73123 STAT2 (open-drain). LOW = charge done
CHARGE_ENABLE P2.05 -- 232201 Enable/disable charging
CHARGE_ACTIVE P1.03 -- 232201 MCP73123 STAT1 (open-drain). LOW = charging
UART1 TX → ESP32 P0.03 GPIO8 (pin 10) 232202 Wirepas Dual-MCU API + config
UART1 RX ← ESP32 P0.04 GPIO9 (pin 11) 232202 Wirepas Dual-MCU API + status
ESP32_RESET P1.10 EN (pin 3) 232202 Boot/reset control
ESP32_READY P2.08 GPIO24 (pin 23) 232202 Boot complete (reused from ACC.INT1)
COEX_REQUEST P2.00 GPIO6 (pin 8) 232202 ESP32 requests airtime
COEX_PRIORITY P2.01 GPIO10 (pin 12) 232202 ESP32 priority
COEX_GRANT P2.02 GPIO23 (pin 21) 232202 nRF54 grants airtime

GPIO Reserve

In this combined variant, P1.03 is used for CHARGE_ACTIVE. P1.02 remains as GPIO reserve. BAT_VOLTAGE uses P1.06 (AIN2) from the always-configured table.

6. Test Points

Combines test points from 232201 and 232202.

Integration-Specific Tests

  • Power-path switchover with WiFi module active (AC loss during WiFi transmission)
  • Battery current draw measurement with WiFi idle
  • Battery current draw measurement with WiFi active
  • Verify no RF interference between WiFi and Wirepas during battery operation
  • Verify charger does not cause voltage droop affecting WiFi module

7. Revision History

Revision Date Author Changes
Rev A TBD TBD Initial prototype