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Also see PaperFT8

Mini-FT8 is built on Karlis Goba’s ft8_lib. It’s also a joint adventure between Zhenxing (N6HAN) and Wei (AG6AQ), with inspiration from DXFT8 by Barb (WB2CBA) and Charley (W5BAA). It has been a great learning platform for me, and I hope you find it just as fun to use. It supports FT8 and FT4 with QMX, QDX, and KH1.

• The DX FT8 team — Barb (WB2CBA), Charley (W5BAA), and Paul (G8KIG) — for the inspiration.
• Zhenxing (N6HAN) — for helping build the audio/DSP path (UAC) and autoseq. This project would not have been possible without his help.
• Karlis Goba — for ft8_lib. Thanks also to Shawn Rutledge for non-standard callsign support.
• OpenAI and Anthropic — for their incredible coding assistance.

(I have no affiliation with the vendors.)

• Must order: https://shop.m5stack.com/products/m5stack-cardputer-adv-version-esp32-s3 or from digikey: https://www.digikey.com/en/products/detail/m5stack-technology-co-ltd/K132-ADV/27685158
• Optional: https://shop.m5stack.com/products/gps-bds-unit-v1-1-at6668 (PORTA GPS for Date/Time/Grid; other UART NMEA GPS modules work too)
• Optional: M5Stack LoRa-1262 cap GNSS (set GNSS_LoRa:ON; only the GNSS is used)
• Optional: DS3231 RTC module on I2C G8/G9 (for retained UTC date/time without GPS)
• For KH1 TX : https://shop.m5stack.com/products/4pin-buckled-grove-cable, for a custmized serial cable
• For KH1 RX: USB C Microphone Adapter, Other adapters may also work, but this one is confirmed. (V2.0.2 Supports Cardputer direct microphone in, so the USB-C adapter becomes optional, choose KH1-Mic)

73, Wei AG6AQ

• R / T / B / S / G / Q / D / C: switch to the selected mode. Press the same mode key again to return to RX.
• M / N / O: jump to MENU page 1 / 2 / 3. Press the current page key again to return to RX.
• `: cancel TX globally in RX, TX, and STATUS when not editing.
• ▲ / ▼: page up / page down in RX, TX, BAND, MENU, QSO, and Delete.
• ◀ / ▶: move left / right in QSO-SNR, STATUS date/time, MENU P2 (N->2).
• 1..6: always select the currently visible row in the active mode.

• ` acts as ESC where applicable.
• Text Edit: Backspace deletes, ` cancels, Enter saves.

• A standalone first install requires the full merged image so the 3 MB fatfs partition table is installed. The merged image contains no FATFS payload, so normal reflashing does not overwrite stored files.

• Mini-FT8 and Mini-CW share the fatfs partition. Their files can coexist, and current M5Launcher installs/reinstalls can switch between the applications while preserving an existing compatible FATFS partition. Both applications use 512-byte FATFS and wear-levelling sectors.

• A fresh or invalid FATFS is formatted automatically. erase_flash, a full-chip erase, or an incompatible partition-table change destroys its files.

• Use SD

  • Insert a FAT/FAT32-formatted SD card.
  • In MENU P3 (O), press 5 (Copy files to SD). All files will be copied to the SD card.
  • If the result shows Missed, a reboot will usually fix it.

• Use pc_terminal.py

  • On the M5 Cardputer, press C to enter communication mode.
  • On the PC, run python .\pc_terminal.py COM11 for interactive use with multiple commands.
  • On the PC, run python .\pc_terminal.py COM11 read 20260113.txt for a single command.

Mini-FT8 supports two GPS sources selected from MENU P3 (O -> 4):

• GNSS_LoRa:OFF uses the PORTA GPS wiring below. Both 9600 and 115200 baud GPS modules are supported and auto-detected. Make sure the micro swithch is on the left. Once Mini-FT8 gets its time/grid, the GPS can be removed, this is important for KH1.
• GNSS_LoRa:ON uses the M5Stack LoRa-1262 cap GNSS on UART2 (RX=G15, TX=G13) at 115200 baud. The LoRa/SX1262 radio side is not used. This source can keep running while KH1 CAT uses PORTA/UART1.

When GNSS_LoRa is ON, the physical G4/G5 debug UART path is disabled and the pins are left as floating inputs to avoid conflicts. USB Serial/JTAG host commands still work.

The GPS view shows the active source on its first line.

┌──────────────────┐                 ┌─────────────────────────────┐
│ GPS              │                 │ Cardputer ADV               │
│                  │                 │ PORTA                       │
│ GND ─────────────┼─────────────────┤ GND                         │
│ VDD ─────────────┼─────────────────┤ 5V                          │
│ RX  ─────────────┼<──(Not Used)────┤ TX (G2)                     │
│ TX  ─────────────┼────────────────>┤ RX (G1)                     │
└──────────────────┘                 │                             │
                                     │ SW: 5VOUT (Left)            │
                                     └─────────────────────────────┘

Mini-FT8 can use an optional DS3231 module as an external UTC clock. Connect it to the Cardputer Adv shared I2C bus: SDA=G8, SCL=G9, plus module power and ground. On boot, a valid DS3231 time is used before the ESP RTC or saved Station.txt time. Status S -> 6 appends R when the active time came from the DS3231, and appends G after a full GPS time sync. GPS and manual time updates write the DS3231 when it is present; FT8 decode fine corrections do not.

• TX Only (sotamat)

┌──────────────────┐                 ┌────────────────────────────┐
│ KH1 RS232        │                 │ Cardputer ADV              │
│                  │                 │ PORTA                      │
│ GND ─────────────┼─────────────────┤ GND                        │
│                  │                 │ 5V (NC)                    │
│ Tip(Rx) ─────────┼<────────────────┤ TX (G2)                    │
│ Ring(TX) ────────┼───(Not Used)───>┤ RX (G1)                    │
└──────────────────┘                 │                            │
                                     │ SW: NA                     │
                                     └────────────────────────────┘

• TX + RX (FT8/FT4 QSO) (V2.0.2 Supports Cardputer direct microphone in, so the USB-C adapter becomes optional, choose KH1-Mic)
  • Use a USB-C audio/mic adapter for RX. Tested adapter: Amazon B0FWC9ZFC4. Other adapters may also work, but this one is confirmed.
  • Supply 5 V to PORTA; otherwise, the USB-C OTG port will not be powered. Make sure the micro swithch is on the right

┌──────────────────┐
│ Power Cable      │
│ GND ─────────────┼─────────┐
│ 5V  ─────────────┼─────┐   │
└──────────────────┘     |   |
┌──────────────────┐     |   |       ┌────────────────────────────┐
│ KH1 RS232        │     |   |       │ Cardputer ADV              │
│                  │     |   |       │ PORTA                      │
│ GND ─────────────┼─────)───┴───────┤ GND                        │
│                  │     └───────────┤ 5V                         │
│ Tip(Rx) ─────────┼<────────────────┤ TX (G2)                    │
│ Ring(TX) ────────┼── (Not Used)───>┤ RX (G1)                    │
└──────────────────┘                 │                            │
                                     │ SW: 5VIN (Right)           │
                                     └────────────────────────────┘

• Mini-FT8 automatically sets KH1 TX power to 2 W.
• For best RX performance, reduce AF volume to 05 or 06.