BLE RGB LED Board

flux

Routing was partially completed: the D1→D32 LED data chain is routed, plus several support/control nets including level-shifter LED data, charger ISET/ILIM/TMR, BAT_NTC, CHG_STAT_N, and USB-C CC/ESD connections.
Open items:
  • The board is not fabrication-ready yet.
  • 88 airwire issues remain, mainly power distribution and blocked control/debug routes.
  • The compact charger/battery/power area needs either a full-board autorouter pass or small placement cleanup.
  • Key unrouted items include BAT_PLUS, VBUS, SYS, LED_VDD, 3V3/GND strategy, LED_EN, RESET_N, PGOOD_N, SWD reroute, USB D+/D− reserved ESD lines, and antenna-related copper details.
  • I updated Layout Plan with the partial routing status.
Suggested next steps:
  1. Slightly spread U2/J2/U5/U3 power area and rerun routing.
  2. Route power with wider copper/pours rather than skinny traces.
  3. Re-route SWD/reset cleanly.
  4. Run full DRC after the next routing pass.
S

sullys

keep working til it's finished please

flux

I’ll keep going: first I’ll open up the congested power/charger area, then continue routing remaining power, debug, reset, and status nets, with checks after each cleanup pass.

flux

I’m blocked now because the account has no available ACUs, so I can’t continue executing layout/routing actions.
Accomplished in this session:
  • Re-checked the routing state and confirmed the main blocker is still the tight charger/battery area around U2/J2.
  • Removed leftover conflicting SWD trace segments that were causing copper-overlap problems.
  • Expanded the board from 80×40 mm to 90×42 mm to improve routing space and reduce density.
Open items:
  • Re-place/spread U2, J2, R5/R7/R8/R9, U3, U5, and nearby passives into the new extra space.
  • Continue routing remaining airwires, especially BAT_PLUS, VBUS, SYS, LED_VDD, 3V3/GND, LED_EN, RESET_N, PGOOD_N, SWD, and USB D+/D− reserved/ESD lines.
  • Run DRC after routing and clean any remaining conflicts.
  • Update the Layout Plan after the next completed routing pass.
Check ACUs
List routing blockers
Suggest charger placement
Run DRC
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Files

Schematic

Layout

Preview

Project Specification — BLE RGB LED Display
Project Overview
Status: Draft. Compact rechargeable BLE-controlled 4x8 RGB LED display board using an ANNA-B112 BLE module, 32 SK6812MINI-E addressable RGB LEDs, USB-C charging, and a single-cell LiPo battery.
Intended Use
Prototype wearable/portable LED display or indicator. The board is intended for low-to-moderate brightness animations controlled over Bluetooth Low Energy.
What the Device Should Do
  • Receive BLE commands.
  • Drive a 4x8 RGB LED display.
  • Recharge from a USB-C 5 V source.
  • Operate from a thin single-cell protected LiPo pack.
  • Report charge status, power-good state, and battery voltage to firmware.
  • Allow SWD programming/debug.
Main Features
  • BLE: ANNA-B112-01B nRF52832-based module.
  • Display: 32x SK6812MINI-E pixels in a 4x8 logical matrix.
  • Power: USB-C sink input, BQ24074 charger/power-path IC, TPS78233 3.3 V LDO.
  • LED rail: MP5075 load switch controlled by firmware, SN74LVC1T45 data level shifter.
  • Protection/debug: USB/ESD protection, reset switch, SWD header.
System Architecture
Diagram



  
    
  
  
    
  



























USB-C 5 V power input
BQ24074 charger and power path
Protected 1-cell LiPo pack with NTC
SYS rail
TPS78233 3.3 V LDO
ANNA-B112 BLE module
MP5075 LED load switch
LED_VDD
32x SK6812MINI-E RGB LEDs
SN74LVC1T45 level shifter
Battery ADC divider
Charge and power-good status
2x3 SWD header
Hardware Subsystems
  • USB-C input: sink-only USB-C power input with CC pull-downs and ESD protection. USB data is reserved/not used.
  • Charging/power path: BQ24074 powers SYS and charges a 1-cell LiPo.
  • BLE control: ANNA-B112 module runs application firmware and handles BLE communication.
  • LED display: SK6812MINI-E LEDs daisy-chain data from D1 through D32.
  • LED power control: MP5075 gates LED power; firmware should default LEDs off until battery/SYS conditions are safe.
  • Debug/programming: SWD header and reset switch.
Interfaces and Connections

Table

InterfaceNets / ComponentsNotes
USB-C powerJ1, VBUS, GND, CC1, CC2Power-only sink; no USB PD.
BatteryJ2, BAT_PLUS, BAT_NTC, GNDRequires approved protected 1-cell pack and verified connector polarity.
SWDJ3, SWDIO, SWDCLK, RESET_N, 3V3, GNDProgramming/debug.
LED dataLED_DATA_RAW, LED_DATA_SHIFTED, LED_DIN_1BLE module drives level shifter; shifted data drives D1.
StatusCHG_STAT_N, PGOOD_NActive-low charger/power-good signals to MCU.
Battery senseVBAT_ADCDivider + filter to MCU ADC.
Power and Runtime Expectations
Runtime is dominated by LED brightness. Full-white theoretical LED current can approach about 1.9 A for 32 pixels at 60 mA/pixel, so long battery life requires firmware current limiting and low average brightness.
Power Tree and Power Budget
See the separate Power and Runtime Notes file for detailed current modes and battery-life assumptions.
Manufacturing and Assembly Expectations
  • Intended as a compact prototype PCB, likely 4-layer for RF/power/return-path quality.
  • All external connector pinouts and footprints must be verified before fabrication.
  • RF antenna geometry and keepout must be checked against the u-blox integration guidance before ordering boards.
Firmware-Relevant Hardware Requirements
  • Keep LED_EN low at boot, reset, debugger halt, and brownout when possible.
  • Measure VBAT_ADC before and during LED operation.
  • Use brightness/current limiting; avoid sustained full-white operation.
  • Advertise/connect over BLE and accept display commands.
  • Use SWD for flashing/recovery.
Physical Design Expectations
  • Compact board with LEDs arranged as a clear 4x8 matrix.
  • BLE module antenna at board edge with required keepout/tuning geometry.
  • USB-C accessible at an edge.
  • Battery connector accessible but mechanically protected.
  • Thin battery should sit behind or beside the board without intruding into antenna keepout.
Important Design Decisions
  • BLE module instead of discrete RF design to reduce RF risk.
  • BQ24074 selected for integrated charger and power-path behavior.
  • Direct LiPo/SYS-powered LED rail selected for compactness, accepting reduced guaranteed LED behavior near low battery.
  • Hardware LED power switch included so firmware can completely remove LED power.
Assumptions
  • Battery is a protected 1-cell LiPo with compatible NTC and connector polarity.
  • USB-C is used for 5 V power only.
  • The display will normally run at reduced brightness to meet runtime and thermal goals.
  • ANNA-B112 lifecycle/variant suitability is still to be confirmed.
Change Notes
  • Initial schematic created with BLE, charger, power path, 3.3 V rail, LED chain, level shifter, battery monitor, SWD, reset, and protection blocks.
  • Current layout is not production-ready; it still needs compact placement, routing, antenna implementation, and DRC cleanup.

  • Project Overview

  • Intended Use

  • What the Device Should Do

  • Main Features

  • System Architecture

  • Hardware Subsystems

  • Interfaces and Connections

  • Power and Runtime Expectations

  • Power Tree and Power Budget

  • Manufacturing and Assembly Expectations

  • Firmware-Relevant Hardware Requirements

  • Physical Design Expectations

  • Important Design Decisions

  • Assumptions

  • Change Notes