RickRoll Wristband

What is it?

This is a project of a wearable watch with a secret rickroll spam Wi-Fi function based on a LilyGo T-Wristband device. The watch uses deepsleep mode to reduce power consuption and also has debug mode, that loads webrepl via Wi-Fi (station or access point mode).

This repository contains:

• Custom MicroPython-1.19.1 firmware for ESP32
• Instruction how to build your own for a different version
• A code of watch app with rickroll function

Special thanks

• MicroPython (micropython/micropython)
• ST7789_mpy (russhughes/st7789_mpy)

How to build

Step 1

Download last MicroPython stable version (e.g. 1.9.1), st7789_mpy driver and esp-idf tool:

git clone -b v1.9.1 https://github.com/micropython/micropython.git
git clone https://github.com/russhughes/st7789_mpy.git
git clone -b v4.4.3 --recursive https://github.com/espressif/esp-idf.git

Step 2

Install esp-idf and activate it. Make sure that you use non-virtualenv python.

cd esp-idf
./install.sh
. ./export.sh
cd ..

Step 3

Build mpy-cross tool:

cd micropython/mpy-cross
make
cd ../..

Step 4

Insert two additional functions into ESP32 network.WLAN: esp_wifi_set_channel and esp_wifi_80211_tx. The first one is used to select specific channel and the second we can use to transfer some raw data package. You can find a place to put them at micropython/ports/esp32/network_wlan.c. If you use 1.19.1 version of MicroPython you can simple apply the patch in this repo. Otherwise you have to add two includes:

#include "py/objarray.h"
#include "py/binary.h"

And two functions:

STATIC mp_obj_t network_wlan_channel(mp_obj_t self_in, mp_obj_t channel) {
    wifi_mode_t mode;
    esp_exceptions(esp_wifi_get_mode(&mode));
    if ((mode & WIFI_MODE_STA) == 0) {
        mp_raise_msg(&mp_type_OSError, MP_ERROR_TEXT("STA must be active"));
    }

    mp_int_t wifi_channel = 0;
    if (mp_obj_get_int_maybe(channel, &wifi_channel)) {
        esp_exceptions(esp_wifi_set_channel(wifi_channel, WIFI_SECOND_CHAN_NONE));
    } else {
        mp_raise_msg(&mp_type_TypeError, MP_ERROR_TEXT("Channel must be integer value"));
    }

    return mp_const_none;
}
STATIC MP_DEFINE_CONST_FUN_OBJ_2(network_wlan_channel_obj, network_wlan_channel);

STATIC mp_obj_t network_wlan_sendraw(size_t n_args, const mp_obj_t *args) {
    wifi_mode_t mode;
    esp_exceptions(esp_wifi_get_mode(&mode));

    bool en_sys_seq = 0;
    if (n_args == 3) {
        en_sys_seq = mp_obj_is_true(args[2]);
    }

    mp_obj_array_t* a_ptr = MP_OBJ_TO_PTR(args[1]);
    if (a_ptr->typecode != BYTEARRAY_TYPECODE) {
        mp_raise_msg(&mp_type_TypeError, MP_ERROR_TEXT("Package must be a bytestring"));
    }

    byte* packet = (byte*)a_ptr->items;
    size_t packet_len = a_ptr->len;

    int result = esp_wifi_80211_tx(mode & WIFI_MODE_STA ? ESP_IF_WIFI_STA : ESP_IF_WIFI_AP, packet, packet_len, en_sys_seq);

    return mp_obj_new_int(result);
}
STATIC MP_DEFINE_CONST_FUN_OBJ_VAR_BETWEEN(network_wlan_sendraw_obj, 2, 3, network_wlan_sendraw);

You also have to add function objects into methods table:

STATIC const mp_rom_map_elem_t wlan_if_locals_dict_table[] = {
    ...
     { MP_ROM_QSTR(MP_QSTR_channel), MP_ROM_PTR(&network_wlan_channel_obj) },
     { MP_ROM_QSTR(MP_QSTR_sendraw), MP_ROM_PTR(&network_wlan_sendraw_obj) },
};

Step 5

Copy some fonts from st7789 c-module:

cp st7789_mpy/fonts/bitmap/vga2_*.py micropython/ports/esp32/modules/

And build the firmware:

make USER_C_MODULES=../../../../st7789_mpy/st7789/micropython.cmake FROZEN_MANIFEST="" FROZEN_MPY_DIR=./modules