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Malher Mycelium

A fully modular Meshtastic device based on the ultra-low-power nRF52840. Supports 22 dBm with the HT-RA62 or up to 1W using the E22-900M30S. The compact core PCB scales via side modules (display, GPS, sensors). Designed in Mexico for the community.

Pictures

| PCB Front (Top) | PCB Back (Bottom) | |--------------------------------------|--------------------------------------| | <img src="https://github.com/MalherLabs/Mycelium/blob/main/Images/pcb-top-bare.png?raw=true" height="500" alt="PCB Top Bare"> | <img src="https://github.com/MalherLabs/Mycelium/blob/main/Images/pcb-bottom-bare.png?raw=true" height="500" alt="PCB Bottom Bare"> |

<details><summary>More Pictures (3D, Assembled, With Case)</summary>

3D Render

| PCB Front (Top) | PCB Back (Bottom) | |--------------------------------------|--------------------------------------| | <img src="https://github.com/MalherLabs/Mycelium/blob/main/Images/pcb-top-ecad.png?raw=true" height="500" alt="PCB Top Bare"> | <img src="https://github.com/MalherLabs/Mycelium/blob/main/Images/pcb-bot-ecad.png?raw=true" height="500" alt="PCB Bottom Bare"> |

PCB Assembled HT-RA62 Variant with GPS module

| PCB Assembled Front (Top) | PCB Assembled Back (Bottom) | |--------------------------------------|--------------------------------------| | <img src="https://github.com/MalherLabs/Mycelium/blob/main/Images/pcb-top-populated_ht.png?raw=true" height="500" alt="PCB Top Bare"> | <img src="https://github.com/MalherLabs/Mycelium/blob/main/Images/pcb-bottom-populated.png?raw=true" height="500" alt="PCB Bottom Bare"> |

PCB Assembled E22 Variant with OLED 1.3 Screen, GPS INA226

| PCB Assembled Front (Top) | | |--------------------------------------|--------------------------------------| | <img src="https://github.com/MalherLabs/Mycelium/blob/main/Images/pcb-top-populated_e22.png?raw=true" height="500" alt="PCB Top Bare"> | |

Fully Assembled Radio with optional Baofeng Clip

| Assembled Radio Front | Assembled Radio Back | |--------------------------------------|--------------------------------------| | <img src="https://github.com/MalherLabs/Mycelium/blob/main/Images/radio-assembled-front.png?raw=true" height="500" alt="PCB Top Bare"> | <img src="https://github.com/MalherLabs/Mycelium/blob/main/Images/radio-assembled-back.png?raw=true" height="500" alt="PCB Bottom Bare"> |

</details>

Features

• Compact base PCB: 39 mm × 65 mm, expandable as required
• nRF52840 Pro Micro–compatible module

LoRa Radio Support

• Support for 1 W Ebyte E22-900M30S or Heltec HT-RA62 LoRa modules
• On-board 3.3 V to 5 V boost converter to supply the E22 module when 1 W TX power is used

Power Management

• On-board power switch (optional)
• PH2.0-2 battery connector, compatible with most lithium batteries (optional)
• Battery voltage sensing (optional)
• MOSFET-based power control to enable or disable the GPS module (optional)

User Interface

• User button and reset button (optional)
• Support for OLED displays: (optional)
  • 1.3" SH1106
  • 0.96" SSD1306
• SMD buzzer for message and event notifications (optional)
• Header for PEC11 rotary encoder for menu navigation and canned messages (optional)

Sensors and Expansion

• Support for ATGM336H GPS module (optional)
• Support for INA226 current sensing (optional)

Variants & Assembly Options

The board is designed with full modularity. You can build exactly what you need:

• Base → Minimal, cheapest, lowest power consumption
• Standard → Recommended for most users (ready-to-use daily driver)
• Extended → Fully loaded (you can pick and choose any of the optional modules)

| Module | Base Variant | Standard Variant | Extended Variant | |-------------------------------------------------|---------------------------------------|---------------------------------------|-----------------------------------------------| | nRF52840 ProMicro board | ✅ Required | ✅ Required | ✅ Required | | LoRa radio module | ✅ Required<br>Choose one:<br>• HT-RA62 (22 dBm)<br>• E22-900M30S (30 dBm / 1 W) | ✅ Required<br>Choose one:<br>• HT-RA62 (22 dBm)<br>• E22-900M30S (30 dBm / 1 W) | ✅ Required<br>Choose one:<br>• HT-RA62 (22 dBm)<br>• E22-900M30S (30 dBm / 1 W) | | +5V Boost Regulator | ⚠️ Only if E22-900M30S is used | ⚠️ Only if E22-900M30S is used | ⚠️ Only if E22-900M30S is used | | Power switch | ❌ Solder bridge JP1 | ✅ Required | ✅ Required | | Battery connector (PH2.0-2) | ❌ Connect Battery directly to PCB | ✅ Required | ✅ Required | | Battery voltage sensing | ❌ | ✅ Required | ✅ Required | | Reset button | ❌ | ✅ Required | ✅ Required | | User button | ❌ | ✅ Required | ✅ Required | | OLED display<br>(1.3" SH1106 or 0.96" SSD1306) | ❌ | ❌ | ✅ Optional (choose one) | | GPS module (ATGM336H) | ❌ | ❌ | ✅ Optional | | GPS power MOSFET switch | ❌ | ❌ | ⚠️ Required only if GPS is populated | | SMD Buzzer (message alert) | ❌ | ❌ | ✅ Optional | | Rotary encoder (Canned Messages) | ❌ | ❌ | ✅ Optional | | INA226 current sense (CJMCU-226 module) | ❌ Solder bridge JP4 | ❌ | ✅ Optional |

How to choose your build

• Base → Ultra-compact, ultra-low-power node (perfect for solar or long-term deployment).
• Standard → The sweet spot for 95 % of users (all basic features + battery management).
• Extended → Add only the modules you actually want. Everything uses standard footprints/headers — no conflicts.

Bill of Materials (BOM)

<details><summary>Base Variant – HT-RA62 (22 dBm)</summary>

| Designators | Qty | Type | Part Number / Value | Package | Link to Supplier | Notes | |-----------------|-----|-----------------------|--------------------------|---------|----------------------------------------------------------------------------------|------------------------| | C4 | 1 | Ceramic Capacitor | 22 µF / 16 V | 0805 | AliExpress | | | JP1, JP4 | 2 | Solder Bridge | N/A | N/A | N/A | Solder bridges | | U2 | 1 | NRF52840 Module | NRF52840 ProMicro | SMD | AliExpress | Core MCU | | U3 | 1 | LoRa Radio Module | HT-RA62 | SMD | AliExpress | | | N/A | 1 | Antenna Connector | SMA-Female | SMA | AliExpress | |

</details> <details><summary>Base Variant – E22-900M30S (30 dBm / 1 W)</summary>

| Designators | Qty | Type | Part Number / Value | Package | Link to Supplier | Notes | |--------------------------|-----|---------------------------|--------------------------|---------|----------------------------------------------------------------------------------|------------------------| | C1, C2, C3 | 3 | Ceramic Capacitor | 100 µF / 10 V | 1206 | AliExpress | | | C4, C5, C6 | 3 | Ceramic Capacitor | 22 µF / 16 V | 0805 | [AliExpress](https://www.aliexpress.com/wholesale?Sear