Modules

Mesh

A LoRa radio and a GNSS receiver for the Kode Dot: messages that travel far and your position with no network, with the pins for your code.

What it is

The Mesh module lets the Kode Dot send messages to radios far away and know where it is. It needs no Wi-Fi and no phone, so it works where neither reaches, out in the hills or during a blackout. It carries two parts:

• A LoRa radio, which sends short messages a long way on very little power, to other Kode Dots with the module and to LoRa radios with the same settings. It has a sub-GHz port and a 2.4 GHz port.
• A GNSS receiver, which listens to GPS and the other satellite systems and gives position and time.

To see it work before writing code, install MeshKode. It turns the Kode Dot into a Meshtastic node, with chat, a map and the position of every node it hears. TBD: its listing on the marketplace. The radio is a NiceRF LoRa2021, with a Semtech LR2021 inside, and the receiver a Minewsemi ME31GR02.

How it is connected

The module comes in its own case and plugs into the header on the top edge. Inside, its board sits on the interposer, a passive adapter that carries every line straight through, so the GPIOs on this page are the header's own.

1. Screw an antenna on each connector on top of the case. Both stand upright.
2. Seat the module on the top edge of the Kode Dot. The pins enter the header and the case rests against the back.
3. Open MeshKode, or your own app for the module. MeshKode shows the nodes it hears and, outdoors, your position.

The radio uses eight GPIOs: the SPI, a busy line, a reset and two DIOs. The receiver uses six: a UART at 115200 baud, a reset, a pulse per second and an I2C pair. All at 3.3 V. "Pin" is the header's pin, the same as J401's on the board, and the direction is the Kode Dot's:

The labels the case prints beside the header, screen up and top edge towards you:

With the Kode Dot upright and the edge seen from above, left and right swap. The schematic and the KiCad sources are in hardware/mesh.

Specifications

The module:

The radio:

Your country's rules say what you may transmit on each band, at what power and how often. The table says what the hardware can do.

The receiver:

Gotchas

Example code

For the LoRa radio, the library is RadioLib, the one Meshtastic uses, with its LR2021 driver and the pins from the table. For the receiver's sentences any NMEA library works, and ESP-IDF ships an example, peripherals/uart/nmea0183_parser.

This example takes the receiver out of reset and copies everything it sends to the log. In idf.py monitor you will see NMEA sentences, lines starting with $, once a second. Indoors they come with empty fields until the receiver sees satellites.

/*
 * mesh_gnss.c - 2026-10-14 - from Kode with love
 *
 * Copies to the log what the GNSS receiver of the Mesh module says. Takes
 * the receiver out of reset with GPIO8 and opens its UART at 115200 baud on
 * GPIO9 and GPIO11. In the monitor you will see NMEA sentences, lines that
 * start with $, once a second; indoors they come with empty fields.
 */
#include <stdio.h>
#include "driver/gpio.h"
#include "driver/uart.h"
 
#define GNSS_RESET        GPIO_NUM_8    /* active low, no pull-up on the module */
#define GNSS_DATA_IN      GPIO_NUM_9    /* the NMEA arrives here */
#define GNSS_COMMAND_OUT  GPIO_NUM_11   /* commands to the receiver */
 
/* Takes the receiver out of reset and logs every byte it sends. */
void app_main(void)
{
    gpio_set_direction(GNSS_RESET, GPIO_MODE_OUTPUT);
    gpio_set_level(GNSS_RESET, 1);
 
    uart_config_t uart = {
        .baud_rate = 115200,
        .data_bits = UART_DATA_8_BITS,
        .parity = UART_PARITY_DISABLE,
        .stop_bits = UART_STOP_BITS_1,
        .source_clk = UART_SCLK_DEFAULT,
    };
    uart_driver_install(UART_NUM_1, 2048, 0, 0, NULL, 0);
    uart_param_config(UART_NUM_1, &uart);
    uart_set_pin(UART_NUM_1, GNSS_COMMAND_OUT, GNSS_DATA_IN, UART_PIN_NO_CHANGE, UART_PIN_NO_CHANGE);
 
    uint8_t text[256];
    while (1) {
        int length = uart_read_bytes(UART_NUM_1, text, sizeof(text), portMAX_DELAY);
        fwrite(text, 1, length, stdout);   /* every sentence brings its own line end */
    }
}

Compiled on the date in the header with ESP-IDF v6.1. TBD: a run on a module.

In the SDK

• kode.h: in a kodeOS app, kode_exp_power(true) switches the header's 3.3 V on, kode_exp_lend() takes the module's 14 positions under a name and gives you their GPIO numbers, and kode_exp_ctrl() hands you a free SPI, UART and I2C controller for the radio and the receiver.
• TBD: a LoRa2021 driver in kode-sdk. Today RadioLib drives the LR2021.
• TBD: an NMEA parser in kode-sdk.