Board Refactor Plan

1:34

Following system rules for planning.

Clarifying tool usage for planning.

Planning queries and project guidelines.

Clarifying formatting and tool use.

Accessing knowledge base.

Creating a detailed execution plan.

I’ve built a plan to refactor your board to LoRa‑E5 only with solar LiFePO4 VSYS, SWD, and SMD edge pads, preserving RF to U4 → J2.

Cleanup & RF

Remove legacy/THT power/IO; keep U4/J2. Clear orphans. Define VSYS (set net types/voltages).

Solar LiFePO4 → VSYS

Add Solar+/Solar− and Batt+/Batt− pads.
PFET ideal‑diode reverse protection + OVP on solar input.
LiFePO4 charger capped at 50 mA; power‑path to VSYS; charge/protect indicators.

Rails from VSYS

Low‑Iq 3.3 V LDO with proper decoupling; verify dropout vs LiFePO4 min voltage (include peaks).
5 V boost 30 mA cont / 40 mA peak, with in/out caps and 5V_OUT pad.

Debug & I/O pads

Tag‑Connect TC2030 SWD: SWDIO/PA13, SWCLK/PA14, NRST (pull‑up), optional SWO/PB3, 3V3, GND.
Castellated SMD 2.54 mm pads:
- I2C SDA/SCL with 4.7 kΩ pull‑ups to 3V3; note maximum 400 pF bus capacitance.
- UART pads on PA2/PA3.
- Two one‑wire pads on PB13/PB15 with 2‑pad jumpers selecting 3.3 V (default) or 5 V pull‑ups.
- Adjacent 3V3/5V/GND pads.

Layout & finalize

Compact square outline, U4 centered, blue soldermask; keep power away from RF; preserve 50‑ohm feed to J2.
Replace generics with real MPNs; run ERC/DRC and fix; update description/BOM.

Let me know if you want any tweaks; otherwise click Start on the plan bar to execute.

Plan

#Goal

Refactor the Green Dot 2040E5 board into a LoRa‑E5 (STM32WLE5JC)-only board, adding a low‑power solar LiFePO4 subsystem to generate a well-regulated VSYS power rail, a low‑Iq 3.3 V LDO output, and a 5 V boost output. The design must include Tag‑Connect TC2030 SWD and SMD 2.54 mm castellated edge pads for I2C (with 4.7 kΩ pull‑ups and a 400 pF bus capacitance note), UART (PA2/PA3), and two one‑wire pads (PB13/PB15, with selectable pull‑ups via 2‑pad jumpers: default 3.3 V and optional 5 V), while preserving the RF connection from U4:RFIO to J2. The board should be a compact, square, blue PCB with pads‑only I/O.

#Implementation plan

Clean up and preserve relevant legacy connections
1. Remove legacy/THT power and I/O blocks.
2. Preserve U4 (LoRa‑E5 / STM32WLE5JC) and ensure the RF net (U4:RFIO) remains connected to J2 (IPEX RF).
3. Define VSYS with appropriate net types and voltage levels in ERC.
Implement the solar LiFePO4 power subsystem on VSYS
1. Add SMD edge pads for Solar+/Solar− and Batt+/Batt− connections.
2. Implement PFET reverse protection as an ideal diode along with over-voltage protection (OVP) on the solar input.
3. Integrate a LiFePO4 charger limited to 50 mA capable of powering VSYS, and include charge and protection indicator signals.
Develop voltage rails from VSYS
1. Add a low‑Iq 3.3 V LDO with proper decoupling, ensuring the dropout voltage matches the LiFePO4 minimum.
2. Implement a 5 V boost converter rated for 30 mA continuous and 40 mA peak, with required input/output capacitors and an exposed 5V_OUT pad.
Add debug and I/O pads
1. Place the Tag‑Connect TC2030 SWD connector, connecting it to SWD signals (SWDIO on PA13, SWCLK on PA14, NRST with pull‑up, and optional SWO/PB3), and provide access to 3V3 and GND.
2. Add SMD 2.54 mm castellated edge pads for the following interfaces:
  1. I2C SDA and SCL, with 4.7 kΩ pull‑ups to 3V3 (note the bus capacitance must not exceed 400 pF).
  2. UART on PA2 and PA3.
  3. Two one‑wire interfaces on PB13 and PB15, with 2‑pad jumpers allowing selection between 3.3 V (default) or 5 V pull‑ups.
3. Include adjacent breakout pads for 3V3, 5V, and GND connections.
Finalize the PCB layout
1. Configure the board as a compact square with a blue soldermask.
2. Position U4 (LoRa‑E5 module) centrally, and route power away from the RF paths.
3. Ensure a 50‑ohm controlled impedance feed from U4:RFIO to J2 remains intact.
4. Replace any generic parts with specific MPNs as necessary.
5. Run ERC/DRC and resolve any issues, and update the project description and BOM accordingly.

#Success criteria

The schematic is complete with all required subsystems fully wired and meeting the specified power rail and I/O configurations.
The RF net from U4:RFIO to J2 is preserved without modification.
The solar LiFePO4 subsystem with its protections and charging capability (50 mA cap) is correctly implemented and feeds VSYS.
The 3.3 V LDO and 5 V boost converter outputs are correctly defined and meet target current specifications.
Debug, I2C, UART, and one‑wire pads are placed and function with the required electrical parameters, and the board layout is a compact square with blue soldermask and pads‑only access.

Pick charger IC

Select 3.3V LDO

Choose 5V boost

Flux net settings

I2C pull-up sizing

76 days

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Documents

Documents are markdown text files which describe project goals, capture details, or even simulation outputs.

Assets

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Project Name

Description

The "Green Dot 2040E5" Board is a Node that interfaces RS485 Sensor probes and can log information to the cloud using LoRa Connectivity. It uses the XIAO RP2040 and the LoRa-E5 (STM32WLE5JC) modules from Seeed Studio to do its magic. It also has amazing power management capabilities (Solar charging, Battery protection, etc) that make it very useful for IoT applications #internetOfThings #smartHomeDevices #SeeedStudio #XIAO #LoRa #RP2040 #IoT

Properties

Properties describe core aspects of the project.

Pricing & Availability

Distributor	Qty 1
Arrow	$13.98–$18.87
Digi-Key	$11.61–$14.77
LCSC	$12.72
Mouser	$18.56
TME	$0.80
Verical	$2.88–$10.77

Controls

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