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projects:amateur_radio:meshtastic:diy_devices:ikoka_stick

Ikoka Stick Meshtastic Device

Ikoka! (行こか!)

“行こか?” or “行こか!” is Kansai dialect for “shall we go?” or “let's go!”.

I hope that building these long-range Meshtastic designs inspires you to go on your next DXing adventure.

Features

  • LoRa
    • Up to 33 dBm (2 W) output power
    • 410–493 MHz (433 MHz band) or 850–930 MHz (868/915/923 MHz band)
  • Bluetooth 5 LE
  • Wi-Fi 4 (2.4 GHz)
  • Lithium-ion battery with charging
  • 0.96“ OLED display

Feature set above depends on part selection.

Hardware

Parts Selection

Several options are available depending on the feature set you need.

Microcontroller

LoRa Module

Lithium-ion Battery (4.2V charging termination, optional)

  • 21700 Lithium-ion battery cell (4.2V charge termination; holder: BeilaMoo PA21700*1-SMT/MYOUNG BH-21700-B1BJ001)
  • Lithium-polymer pouch battery cell (4.2V charge termination; connector: Molex PicoBlade 1x02P, pitch 1.25mm)
  • Do not use both a 21700 and LiPo battery simultaneously, they will be shorted together in parallel
Wiring for Battery Charging

You will need a PicoBlade Female-to-Pigtail cable assembly such as Molex 218112-0200. A compatible cable ships with Heltec Wireless and LILYGO LoRa products so you probably have spares you can use. Muzi Works and Rokland also sell compatible cables.

  1. Trim the pigtail length to around 5cm if it is longer
  2. Strip 2mm of insulation from each pigtail, then twist and tin the wire strands
  3. Solder the red pigtail (or pin 1) to the BAT+ pad on the back of the XIAO module
  4. Solder the black pigtail (or pin 2) to the BAT- pad on the back of the XIAO module
  5. Plug the cable into the XIAO Charger connector on the Ikoka Stick

In my previous design, the Ikoka Nano, the XIAO module was SMD soldered onto the board, while the BAT+ pad was soldered through a plated through-hole via. However, the actual solder joint is buried and couldn't be inspected for continuity, quality and ensuring the BAT+ pad was not shorted to the BAT- pad.

In the interest of ease-of-assembly and keeping the XIAO module interchangeable, while not wasting the built-in battery charging circuit on XIAO modules, this approach was chosen instead.

OLED Display (Optional)

  • Generic SSD1306 0.96” OLED display modules with 2.54mm pin headers (AliExpress)

Firmware

GPIO Assignment

XIAO PinFunction XIAO-nRF52840XIAO-ESP32-S3
1 (D0) User button 2 (P0.02) 1
2 (D1) EBYTE E22 - DIO1 3 (P0.03) 2
3 (D2) EBYTE E22 - RST 28 (P0.28) 3
4 (D3) EBYTE E22 - BUSY 29 (P0.29) 4
5 (D4) EBYTE E22 - SPI NSS 4 (P0.04) 5
6 (D5) EBYTE E22 - RXEN 5 (P0.05) 6
7 (D6) SSD1306 OLED - I2C SDA43 (P1.11) 43
8 (D7) SSD1306 OLED - I2C SCL44 (P1.12) 44
9 (D8) EBYTE E22 - SPI SCK 45 (P1.13) 7
10 (D9) EBYTE E22 - SPI MISO 46 (P1.14) 8
11 (D10)EBYTE E22 - SPI MOSI 47 (P1.15) 9
12 SSD1306 OLED - 3.3V 3V3 3V3
13 GND GND GND
14 NC 5V 5V

Meshtastic Compatibility

The XIAO module is intended to be socketed with pin headers/pin sockets, to allow swapping out modules depending on what features are needed (Bluetooth, Wi-Fi, different power consumption profiles, etc.); Compatibility with official Meshtastic firmware depends on the inserted XIAO board.

XIAO-nRF52840

XIAO-ESP32-S3

  • Pin definitions are different from the officially-supported Seeed Xiao ESP32-S3 Kit
    • This is because Seeed uses GPIOs on the 30-pin board-to-board press-fit connector instead of the standard XIAO pins
    • A custom firmware must be built (TODO)

PCB Renders

PCB Top

top

PCB Bottom

bottom

Rotating GIF

animation

(Rendered with kicad-render.)

projects/amateur_radio/meshtastic/diy_devices/ikoka_stick.txt · Last modified: by Andrew Yong