# 2G-Sound ## Description Battery-Powered IoT MQTT Notifier with USB-C Power-Path Charging, Multi-Rail Power Architecture, and 3 s Long-Press PFET Power-Gate (MP5014 + LTC2955 + MCU SYS_EN Override) #power_control #long_press #load_switch #sys_en ## Project Details - **Owner:** supcaree - **Created:** 12/13/2025 - **Last Updated:** 2/28/2026 - **Visibility:** Public - **parts_available:** 2025-12-13 - **Board Width:** 54.025mm - **Connectivity:** WiFi, Cellular, USB - **Power Requirements:** USB, Battery - **Software:** Arduino - **Human Interface:** Buttons, Switches - **System Architecture:** ```mermaid flowchart TD USBC["USB-C\nVBUS"] --> U5["USB-C Charger\nBQ25750"] U5 --> Battery["LiPo\n3.7V VBAT"] Battery --> VBAT_Dir["VBAT Direct\nAlways-On"] VBAT_Dir --> U5 VBAT_Dir --> VSYS_SW["High-Side Load Switch\nU10 MP5014"] VSYS_SW --> VSYS["VSYS System Rail"] VSYS --> BB3V3["3.3V Buck-Boost\nU6 TPS63051"] VSYS --> BB6V5["6.5V Boost\nU7 TPS61252"] VSYS --> LCFIL["LC Filter\nL1/C3/C4"] LCFIL --> SIM800L["SIM800L\nU2"] SW1["SW1 Power Button\n3 s Long-Press"] --> U11["Long-Press Controller\nU11 LTC2955"] Battery --> U11 U11 --> VSYS_SW U11 --> CT["CT Delay\nR_CT/C_CT"] CT --> GND["GND"] MCU_Override["MCU GPIO Override\nU1 GPIO2"] --> U11_KILL["Kill Input\nU11 KILL"] U11_KILL --> VSYS_SW BB3V3 --> PG3V3["PG/EN\nU6 PG"] BB6V5 --> PG6V5["PG/EN\nU7 PG"] PG3V3 --> SYS_EN["SYS_EN Net"] PG6V5 --> SYS_EN SYS_EN --> U6_EN["EN\nU6 EN"] SYS_EN --> U7_EN["EN\nU7 EN"] U6_EN --> BB3V3 U7_EN --> BB6V5 ``` - **Board Size:** 54.025 mm x 86.075 mm - **Power Architecture Diagram:** flowchart TD USBC["USB-C\nVBUS"] --> Charger["USB-C Charger\nPower Path"] Charger --> Battery["LiPo\n3.7V VBAT"] Battery --> BB3V3["3.3V Buck-Boost Regulator"] BB3V3 --> Logic["ESP-12F/U3 Logic\n3.3V Rail"] Battery --> LCFIL["LC Filter\nSIM800L VBAT"] LCFIL --> SIM800L["SIM800L"] Battery --> BB6V5["6.5V Boost Converter"] BB6V5 --> Amp["MAX98357A Audio Amp"] Logic --> SW1["SW1 Power Control"] Logic --> SW2["SW2 Volume -"] Logic --> SW3["SW3 Volume +"] Logic --> LED1["LED1 Online"] Logic --> LED2["LED2 Offline"] - **Board Height:** 86.075mm - **Domain:** Consumer Electronics ## Key Components ### B1 — [BH-18650-A1AJ0062](https://www.flux.ai/birkanozer/bh-18650-a1aj0062~gk.md) - Voltage: 4.2V - Manufacturer Part Number: BH-18650-A1AJ006 **Pins:** - NEGATIVE [pin -] - POSITIVE [pin +] ### J1 — [Pin Header 01x03 2.54mm Vertical](https://www.flux.ai/adrian95/pin-header-01x03-254mm-vertical~cp4.md) - Part Type: Connector **Pins:** - Pin_1 [pin 1] - Pin_2 [pin 2] - Pin_3 [pin 3] ### J3 — [Pin Socket 01x08 2.54mm Vertical](https://www.flux.ai/adrian95/pin-socket-01x08-254mm-vertical~cz1.md) - Part Type: Connector - License: https://creativecommons.org/licenses/by/4.0/ **Pins:** - Pin_1 [pin 1] - Pin_2 [pin 2] - Pin_3 [pin 3] - Pin_4 [pin 4] - Pin_5 [pin 5] - Pin_6 [pin 6] - Pin_7 [pin 7] - Pin_8 [pin 8] ### U1 — [WeMos D1 mini](https://www.flux.ai/jharwinbarrozo/wemos-d1-mini~27.md) - Manufacturer Part Number: WeMos_D1_mini - Part Type: Integrated Circuit **Pins:** - 3V3 - 5V - A0 - CS/D8 - D0 - D3 - D4 - GND - MISO/D6 - MOSI/D7 - RST - RX - SCK/D5 - SCL/D1 - SDA/D2 - TX ### U3 — [M2 Mounting Hole](https://www.flux.ai/vasyl/m2-mounting-hole~st.md) **Pins:** - ~ ### U4 — [M2 Mounting Hole](https://www.flux.ai/vasyl/m2-mounting-hole~st.md) **Pins:** - ~ ### U5 — [M2 Mounting Hole](https://www.flux.ai/vasyl/m2-mounting-hole~st.md) **Pins:** - ~ ### U6 — [M2 Mounting Hole](https://www.flux.ai/vasyl/m2-mounting-hole~st.md) **Pins:** - ~ ### U7 — [PAM8403D](https://www.flux.ai/kicad-part-library/pam8403d~3t.md) - Datasheet URL: https://www.diodes.com/assets/Datasheets/products_inactive_data/PAM8403.pdf - Manufacturer Name: Texas Instruments Inc. - Package or Case Code: SOP-16_3.9x9.9mm_P1.27mm - Manufacturer Part Number: PAM8403D **Pins:** - ~{MUTE} [pin 5] - ~{SHDN} [pin 12] - GND [pin 11] - INL [pin 7] - INR [pin 10] - LOUT- [pin 3] - LOUT+ [pin 1] - NC [pin 9] - PGND [pin 15] - PGND [pin 2] - PVDD [pin 4] - PVDD [pin 13] - ROUT- [pin 14] - ROUT+ [pin 16] - VDD [pin 6] - VREF [pin 8] *The full schematic, PCB layout, bill of materials, and interactive design are available at [https://www.flux.ai/supcaree/2g-sound~jf](https://www.flux.ai/supcaree/2g-sound~jf).* --- *Generated from [https://www.flux.ai/supcaree/2g-sound~jf](https://www.flux.ai/supcaree/2g-sound~jf)*