# ESP32 Audio Radio Li-ion Node ## Description Low-power ESP32 audio/radio device with SA828 walkie-talkie module, MAX9814 microphone, PAM8403-driven GD14 bone-conduction output, and single-cell Li-ion charging, power-path, 3.3 V regulation, and battery monitoring. ## Project Details - **Owner:** papachop - **Created:** 4/8/2026 - **Last Updated:** 4/8/2026 - **Visibility:** Public - **Power Requirements:** Single-cell Li-ion battery operation with charging, managed power path, 3.3V regulation, and battery monitoring for ESP32, SA828, GD14, PAM8403, and MAX9814 across idle, active, peak-load, battery-only, and externally powered/charging states. - **Implementation Details:** Updated plan must document battery voltage range, charging input assumptions, power-path behavior during charge/discharge, always-on vs switched domains, typical and peak current budgets per module, startup and duty-cycle assumptions, low-battery thresholds, state-of-charge indication, safety responses, trade-offs, and acceptance criteria for later schematic implementation. ## Key Components ### D1 — [PRTR5V0U2X,215](https://www.flux.ai/openpartlist/prtr5v0u2xc215.md) - Role Details: TVS protection on USB-C VBUS and connector exposed lines - Manufacturer Part Number: PRTR5V0U2X,215 - Manufacturer Name: Nexperia USA Inc. - License: https://creativecommons.org/licenses/by/4.0/ - Role: ESD Protection - Datasheet URL: https://assets.nexperia.com/documents/data-sheet/PRTR5V0U2X.pdf - Part Type: Protection - Package: SOT-143B **Pins:** - GND [pin 1] - I/O1 [pin 2] - I/O2 [pin 3] - VCC [pin 4] ### IC1 — [PAM8403DR](https://www.flux.ai/adrian95/pam8403dr.md) - Manufacturer Part Number: PAM8403DR - License: https://creativecommons.org/licenses/by/4.0/ - Role: Audio Amplifier - Package: SOP-16 - Datasheet URL: https://www.diodes.com/assets/Datasheets/products_inactive_data/PAM8403.pdf - Role Details: Class-D amplifier used to drive GD14 bone-conduction output from audio source - Part Type: Integrated Circuit - Manufacturer Name: Diodes Incorporated **Pins:** - -OUT_L [pin 3] - -OUT_R [pin 14] - +OUT_L [pin 1] - +OUT_R [pin 16] - GND [pin 11] - INL [pin 7] - INR [pin 10] - MUTE [pin 5] - NC [pin 9] - PGND_1 [pin 2] - PGND_2 [pin 15] - PVDD_1 [pin 4] - PVDD_2 [pin 13] - SHND [pin 12] - VDD [pin 6] - VREF [pin 8] ### J1 — [USB4235-03-C](https://www.flux.ai/cherepanyadima/usb4235-03-c.md) - Manufacturer Name: GST - Package: USB-C - Role Details: USB-C sink connector for 5V charging and external system power - Datasheet URL: https://gct.co/files/specs/usb4235-spec.pdf - Role: Power Input Connector - Manufacturer Part Number: USB4235-03-C_REVA - Part Type: Connectors **Pins:** - CC1 [pin A5] - CC2 [pin B5] - DN1 [pin A7] - DN2 [pin B7] - DP1 [pin A6] - DP2 [pin B6] - GND_A [pin A1] - GND_A__1 [pin A12] - GND_B [pin B1] - GND_B__1 [pin B12] - SBU1 [pin A8] - SBU2 [pin B8] - SHIELD [pin SH1] - SHIELD__1 [pin SH2] - VBUS_A [pin A4] - VBUS_A__1 [pin A9] - VBUS_B [pin B4] - VBUS_B__1 [pin B9] ### J2 — [B2B-PH-K-S](https://www.flux.ai/adrian95/b2b-ph-k-s.md) - Package: JST-PH-2 - Package or Case Code: JST_B2B-PH-K-S - Part Type: Connector - Manufacturer Part Number: B2B-PH-K-S - License: https://creativecommons.org/licenses/by/4.0/ - Datasheet URL: https://www.jst-mfg.com/product/pdf/eng/ePH.pdf - Manufacturer Name: JST - Role: Battery Connector - Role Details: 2-pin Li-ion battery connection **Pins:** - 1 [pin 1] - 2 [pin 2] ### J3 — [1769](https://www.flux.ai/adrian95/1769.md) - Role Details: 2-wire connection for external GD14 bone-conduction transducer/module - Manufacturer Name: Adafruit Industries - Manufacturer Part Number: 1769 - Datasheet URL: https://www.verical.com/datasheet/adafruit-headers---pcb-receptacles-1769-4576025.pdf - Part Type: Connector - Role: Audio Output Connector - Package: JST-PH-2-SMT - License: https://creativecommons.org/licenses/by/4.0/ **Pins:** - 1 [pin 1] - 2 [pin 2] ### LED1 — [Low Power Green LED](https://www.flux.ai/corynrobinson/low-power-green-led.md) - Package: 0603 - Part Type: LED - Role: Status LED - Role Details: Green power-good indicator driven from charger PGOOD through R6 - Forward Voltage: 2V - Package or Case Code: D_0603_1608Metric - Current: 20mA - Manufacturer Name: Dialight - Purchase Url: https://octopart.com/598-8070-107f-dialight-872854?r=sp - Manufacturer Part Number: 598-8070-107F - Datasheet URL: https://octopart.com/datasheet/598-8070-107f-dialight-872854 **Pins:** - A - K ### LED2 — [LTST-C190KRKT](https://www.flux.ai/adrian95/ltst-c190krkt.md) - License: https://creativecommons.org/licenses/by/4.0/ - Manufacturer Name: Lite-On Inc. - Role: Status LED - Part Type: LED - Role Details: Red charge-status indicator driven from charger CHG through R7 - Package: 0603 - Datasheet URL: https://optoelectronics.liteon.com/upload/download/DS-22-99-0151/LTST-C190KRKT.pdf - Manufacturer Part Number: LTST-C190KRKT **Pins:** - A [pin 2] - K [pin 1] ### MK1 — [POM-3535P-3-R](https://www.flux.ai/adrian95/pom-3535p-3-r.md) - Role Details: Electret microphone connected to MAX9814 MICIN and MICBIAS - Manufacturer Part Number: POM-3535P-3-R - Datasheet URL: https://www.mouser.com/datasheet/2/334/POM-3535P-3-R-270441.pdf - Package: PC Pins - License: https://creativecommons.org/licenses/by/4.0/ - Role: Microphone Capsule - Part Type: Microphone - Manufacturer Name: PUI Audio, Inc. **Pins:** - 1 [pin N] - 2 [pin P] ### U1 — [ESP32-WROOM-32](https://www.flux.ai/vasy_skral/esp32-wroom-32.md) - Role: MCU - Manufacturer Name: Espressif Systems - Role Details: Main controller handling SA828 UART/PTT, amplifier control, mic sampling, and battery ADC monitoring - Manufacturer Part Number: ESP32-WROOM-32 - Part Type: Integrated Circuit - Datasheet URL: https://www.espressif.com/sites/default/files/documentation/esp32-wroom-32_datasheet_en.pdf - Package: Module **Pins:** - EN [pin 3] - GND [pin 15] - GND [pin 39] - GND [pin 38] - GND [pin 1] - IO0 [pin 25] - IO12 [pin 14] - IO13 [pin 16] - IO14 [pin 13] - IO15 [pin 23] - IO16 [pin 27] - IO17 [pin 28] - IO18 [pin 30] - IO19 [pin 31] - IO2 [pin 24] - IO21 [pin 33] - IO22 [pin 36] - IO23 [pin 37] - IO25 [pin 10] - IO26 [pin 11] - IO27 [pin 12] - IO32 [pin 8] - IO33 [pin 9] - IO34 [pin 6] - IO35 [pin 7] - IO4 [pin 26] - IO5 [pin 29] - NC [pin 32] - RXD0/IO3 [pin 34] - SCK/CLK [pin 20] - SCS/CMD [pin 19] - SDI/SD1 [pin 22] - SDO/SD0 [pin 21] - SENSOR_VN [pin 5] - SENSOR_VP [pin 4] - SHD/SD2 [pin 17] - SWP/SD3 [pin 18] - TXD0/IO1 [pin 35] - VDD [pin 2] ### U2 — [SA828-U](https://www.flux.ai/lcsc/sa828-u.md) - Package or Case Code: WIRELM-TH_G-NICERF_SA828-X - Role Details: UHF/VHF walkie-talkie module interfaced to ESP32 through UART and control pins - Role: Radio Module - Package: Module - Manufacturer Part Number: SA828-U - JLCPCB Part Class: Extended Part - LCSC Part Number: C3001505 - Manufacturer Name: G-NiceRF(思为无线) **Pins:** - 1 [pin 4] - 2 [pin 5] - 4 [pin 7] - 8 [pin 6] - CS [pin 23] - GND [pin 21] - GND [pin 10] - H/L [pin 8] - MIC- [pin 2] - MIC+ [pin 1] - PTT [pin 20] - RXD [pin 18] - SPK [pin 15] - SPK [pin 14] - SPKEN [pin 9] - TXD [pin 19] - VCC [pin 22] - VOL [pin 16] - VOL [pin 17] - VOXEN [pin 3] ### U3 — [MAX9814](https://www.flux.ai/kicad-part-library/max9814.md) - Role Details: Electret microphone amplifier with AGC feeding an ESP32 ADC input - Package: TDFN-14 - Role: Microphone Front End - Manufacturer Part Number: MAX9814 - Package or Case Code: DFN-14-1EP_3x3mm_P0.4mm_EP1.78x2.35mm - Datasheet URL: https://datasheets.maximintegrated.com/en/ds/MAX9814.pdf - Manufacturer Name: Maxim Integrated Products, Inc. **Pins:** - ~{SHDN} [pin 2] - A/R [pin 9] - BIAS [pin 12] - CG [pin 3] - CT [pin 1] - GAIN [pin 10] - GND [pin 7] - GND [pin 4] - GND [pin 11] - GND [pin 15] - MICBIAS [pin 13] - MICIN [pin 8] - MICOUT [pin 6] - TH [pin 14] - VDD [pin 5] ### U4 — [BQ24075RGTT](https://www.flux.ai/jecstronic/bq24075rgtt.md) - Manufacturer Part Number: BQ24075RGTT - License: https://creativecommons.org/licenses/by/4.0/ - Datasheet URL: https://www.ti.com/lit/ds/symlink/bq24075.pdf - Package: VQFN-16 - Part Type: Power Management - Manufacturer Name: Texas Instruments - Role: Battery Charger - Role Details: USB-input single-cell Li-ion charger with system OUT power-path support **Pins:** - ~CE [pin 4] - ~CHG [pin 9] - ~PGOOD [pin 7] - BAT_1 [pin 2] - BAT_2 [pin 3] - EN1 [pin 6] - EN2 [pin 5] - ILIM [pin 12] - IN [pin 13] - ISET [pin 16] - OUT_1 [pin 10] - OUT_2 [pin 11] - SYSOFF [pin 15] - TMR [pin 14] - TS [pin 1] - VSS [pin 8] - VSS_THERMAL_PAD [pin 17] ### U5 — [NCP176BMX330TCG](https://www.flux.ai/ryanf/ncp176bmx330tcg.md) - Package: XDFN6 - Role: Voltage Regulator - Datasheet URL: https://www.mouser.com/datasheet/2/308/1/NCP176_D-2316728.pdf - Package or Case Code: XDFN6 - Manufacturer Part Number: NCP176BMX330TCG - Part Type: Linear Voltage Regulator - Role Details: Low quiescent current 3.3V LDO from charger OUT to logic and analog 3.3V rail - Manufacturer Name: onsemi **Pins:** - EN [pin 4] - FB [pin 2] - GND [pin 3] - IN [pin 6] - N/C [pin 5] - OUT [pin 1] *The full schematic, PCB layout, bill of materials, and interactive design are available at [https://www.flux.ai/papachop/esp32-audio-radio-li-ion-node](https://www.flux.ai/papachop/esp32-audio-radio-li-ion-node).* --- *Generated from [https://www.flux.ai/papachop/esp32-audio-radio-li-ion-node](https://www.flux.ai/papachop/esp32-audio-radio-li-ion-node)*