diff --git a/components/mch2022-rp2040 b/components/mch2022-rp2040
index 2b4cbce..3c859b5 160000
--- a/components/mch2022-rp2040
+++ b/components/mch2022-rp2040
@@ -1 +1 @@
-Subproject commit 2b4cbce95827f6da3841584b8f6e80930f269f21
+Subproject commit 3c859b52f3f8cc3b3969d6a6d57a12f22781f291
diff --git a/main/CMakeLists.txt b/main/CMakeLists.txt
index a381bbb..fd2f49b 100644
--- a/main/CMakeLists.txt
+++ b/main/CMakeLists.txt
@@ -25,6 +25,7 @@ idf_component_register(
          "animation.c"
          "button_test.c"
          "adc_test.c"
+         "webusb.c"
     INCLUDE_DIRS "."
                  "include"
                  "menus"
diff --git a/main/factory_test.c b/main/factory_test.c
index ad286be..4e154c4 100644
--- a/main/factory_test.c
+++ b/main/factory_test.c
@@ -60,6 +60,20 @@ bool test_stuck_buttons(uint32_t* rc) {
     return (state == 0x0000);
 }
 
+bool test_adc_vbat(uint32_t* rc) {
+    float value = 0;
+    esp_err_t res = rp2040_read_vbat(get_rp2040(), &value);
+    *rc = value * 100;
+    return ((res == ESP_OK) && (value < 4.3) && (value > 3.9));
+}
+
+bool test_adc_vusb(uint32_t* rc) {
+    float value = 0;
+    esp_err_t res = rp2040_read_vusb(get_rp2040(), &value);
+    *rc = value * 100;
+    return ((res == ESP_OK) && (value > 4.5));
+}
+
 bool test_sd_power(uint32_t* rc) {
     *rc = 0x00000000;
     // Init all GPIO pins for SD card and LED
@@ -106,8 +120,12 @@ bool run_basic_tests(pax_buf_t* pax_buffer, ILI9341* ili9341) {
     RUN_TEST_MANDATORY("ICE40",  test_ice40_init);
     RUN_TEST_MANDATORY("BNO055", test_bno055_init);
     RUN_TEST_MANDATORY("BME680", test_bme680_init);
-    RUN_TEST_MANDATORY("STUCK BUTTONS", test_stuck_buttons);
-    RUN_TEST_MANDATORY("SD/LED POWER", test_sd_power);
+    
+    /* Run tests */
+    RUN_TEST("STUCK BUTTONS", test_stuck_buttons);
+    RUN_TEST("SD/LED POWER", test_sd_power);
+    RUN_TEST("Battery voltage", test_adc_vbat);
+    RUN_TEST("USB voltage", test_adc_vusb);
     
 
 error:
diff --git a/main/include/webusb.h b/main/include/webusb.h
new file mode 100644
index 0000000..2cd234c
--- /dev/null
+++ b/main/include/webusb.h
@@ -0,0 +1,8 @@
+#pragma once
+
+#include "ice40.h"
+#include "pax_gfx.h"
+#include "ili9341.h"
+#include <freertos/FreeRTOS.h>
+
+void webusb_main(xQueueHandle buttonQueue, pax_buf_t* pax_buffer, ILI9341* ili9341);
diff --git a/main/main.c b/main/main.c
index 3c01c49..1b3dab4 100644
--- a/main/main.c
+++ b/main/main.c
@@ -49,6 +49,8 @@
 #include "menus/start.h"
 
 #include "factory_test.h"
+#include "fpga_download.h"
+#include "webusb.h"
 
 extern const uint8_t wallpaper_png_start[] asm("_binary_wallpaper_png_start");
 extern const uint8_t wallpaper_png_end[] asm("_binary_wallpaper_png_end");
@@ -69,9 +71,29 @@ void display_fatal_error(pax_buf_t* pax_buffer, ILI9341* ili9341, const char* li
     ili9341_write(ili9341, pax_buffer->buf);
 }
 
+void stop() {
+    ESP_LOGW(TAG, "*** HALTED ***");
+    gpio_set_direction(GPIO_SD_PWR, GPIO_MODE_OUTPUT);
+    gpio_set_level(GPIO_SD_PWR, 1);
+    ws2812_init(GPIO_LED_DATA);
+    uint8_t led_off[15] = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0};
+    uint8_t led_red[15] = {0, 50, 0, 0, 50, 0, 0, 50, 0, 0, 50, 0, 0, 50, 0};
+    uint8_t led_red2[15] = {0, 0xFF, 0, 0, 0xFF, 0, 0, 0xFF, 0, 0, 0xFF, 0, 0, 0xFF, 0};
+    while (true) {
+        ws2812_send_data(led_red2, sizeof(led_red2));
+        vTaskDelay(pdMS_TO_TICKS(200));
+        ws2812_send_data(led_red, sizeof(led_red));
+        vTaskDelay(pdMS_TO_TICKS(200));
+        ws2812_send_data(led_off, sizeof(led_off));
+        vTaskDelay(pdMS_TO_TICKS(200));
+    }
+}
+
 void app_main(void) {
     esp_err_t res;
     
+    audio_init();
+    
     const esp_app_desc_t *app_description = esp_ota_get_app_description();
     ESP_LOGI(TAG, "App version: %s", app_description->version);
     //ESP_LOGI(TAG, "Project name: %s", app_description->project_name);
@@ -113,23 +135,21 @@ void app_main(void) {
     if (res != ESP_OK) {
         ESP_LOGE(TAG, "NVS init failed: %d", res);
         display_fatal_error(pax_buffer, ili9341, "Failed to initialize", "NVS failed to initialize", "Flash may be corrupted", NULL);
-        esp_restart();
+        stop();
     }
-    
-    audio_init();
 
     display_boot_screen(pax_buffer, ili9341, "Starting...");
 
     if (bsp_rp2040_init() != ESP_OK) {
         ESP_LOGE(TAG, "Failed to initialize the RP2040 co-processor");
         display_fatal_error(pax_buffer, ili9341, "Failed to initialize", "RP2040 co-processor error", NULL, NULL);
-        esp_restart();
+        stop();
     }
 
     RP2040* rp2040 = get_rp2040();
     if (rp2040 == NULL) {
         ESP_LOGE(TAG, "rp2040 is NULL");
-        esp_restart();
+        stop();
     }
 
     rp2040_updater(rp2040, pax_buffer, ili9341); // Handle RP2040 firmware update & bootloader mode
@@ -140,7 +160,7 @@ void app_main(void) {
     if (rp2040_get_uid(rp2040, rp2040_uid) != ESP_OK) {
         ESP_LOGE(TAG, "Failed to get RP2040 UID");
         display_fatal_error(pax_buffer, ili9341, "Failed to initialize", "Failed to read UID", NULL, NULL);
-        esp_restart();
+        stop();
     }
 
     printf("RP2040 UID: %02X%02X%02X%02X%02X%02X%02X%02X\n", rp2040_uid[0], rp2040_uid[1], rp2040_uid[2], rp2040_uid[3], rp2040_uid[4], rp2040_uid[5], rp2040_uid[6], rp2040_uid[7]);*/
@@ -148,13 +168,13 @@ void app_main(void) {
     if (bsp_ice40_init() != ESP_OK) {
         ESP_LOGE(TAG, "Failed to initialize the ICE40 FPGA");
         display_fatal_error(pax_buffer, ili9341, "Failed to initialize", "ICE40 FPGA error", NULL, NULL);
-        esp_restart();
+        stop();
     }
 
     ICE40* ice40 = get_ice40();
     if (ice40 == NULL) {
         ESP_LOGE(TAG, "ice40 is NULL");
-        esp_restart();
+        stop();
     }
     
     /*display_boot_screen(pax_buffer, ili9341, "Initializing BNO055...");
@@ -162,13 +182,13 @@ void app_main(void) {
     if (bsp_bno055_init() != ESP_OK) {
         ESP_LOGE(TAG, "Failed to initialize the BNO055 position sensor");
         display_fatal_error(pax_buffer, ili9341, "Failed to initialize", "BNO055 sensor error", "Check I2C bus", "Remove SAO and try again");
-        esp_restart();
+        stop();
     }
 
     BNO055* bno055 = get_bno055();
     if (bno055 == NULL) {
         ESP_LOGE(TAG, "bno055 is NULL");
-        esp_restart();
+        stop();
     }*/
 
     /*display_boot_screen(pax_buffer, ili9341, "Initializing BME680...");
@@ -176,13 +196,13 @@ void app_main(void) {
     if (bsp_bme680_init() != ESP_OK) {
         ESP_LOGE(TAG, "Failed to initialize the BME680 position sensor");
         display_fatal_error(pax_buffer, ili9341, "Failed to initialize", "BME680 sensor error", "Check I2C bus", "Remove SAO and try again");
-        esp_restart();
+        stop();
     }
 
     BME680* bme680 = get_bme680();
     if (bme680 == NULL) {
         ESP_LOGE(TAG, "bme680 is NULL");
-        esp_restart();
+        stop();
     }*/
     
     //display_boot_screen(pax_buffer, ili9341, "Initializing AppFS...");
@@ -192,7 +212,7 @@ void app_main(void) {
     if (res != ESP_OK) {
         ESP_LOGE(TAG, "AppFS init failed: %d", res);
         display_fatal_error(pax_buffer, ili9341, "Failed to initialize", "AppFS failed to initialize", "Flash may be corrupted", NULL);
-        esp_restart();
+        stop();
     }
 
     //display_boot_screen(pax_buffer, ili9341, "Initializing filesystem...");
@@ -235,12 +255,40 @@ void app_main(void) {
     /* Start WiFi */
     wifi_init();
     
-    /* Rick that roll */
-    play_bootsound();
+    /* Check WebUSB mode */
+    
+    uint8_t webusb_mode;
+    res = rp2040_get_webusb_mode(rp2040, &webusb_mode);
+    if (res != ESP_OK) {
+        ESP_LOGE(TAG, "Failed to read WebUSB mode: %d", res);
+        display_fatal_error(pax_buffer, ili9341, "Failed to initialize", "Failed to read WebUSB mode", NULL, NULL);
+        stop();
+    }
+    
+    ESP_LOGI(TAG, "WebUSB mode 0x%02X", webusb_mode);
+    
+    if (webusb_mode == 0x00) { // Normal boot
+        /* Rick that roll */
+        play_bootsound();
 
-    /* Launcher menu */
-    while (true) {
-        menu_start(rp2040->queue, pax_buffer, ili9341, app_description->version);
+        /* Launcher menu */
+        while (true) {
+            menu_start(rp2040->queue, pax_buffer, ili9341, app_description->version);
+        }
+    } else if (webusb_mode == 0x01) {
+        display_boot_screen(pax_buffer, ili9341, "WebUSB mode");
+        while (true) {
+            webusb_main(rp2040->queue, pax_buffer, ili9341);
+        }
+    } else if (webusb_mode == 0x02) {
+        display_boot_screen(pax_buffer, ili9341, "FPGA download mode");
+        while (true) {
+            fpga_download(rp2040->queue, get_ice40(), pax_buffer, ili9341);
+        }
+    } else {
+        char buffer[64];
+        snprintf(buffer, sizeof(buffer), "Invalid mode 0x%02X", webusb_mode);
+        display_boot_screen(pax_buffer, ili9341, buffer);
     }
 
     free(framebuffer);
diff --git a/main/menus/start.c b/main/menus/start.c
index fa6e54a..ce2b703 100644
--- a/main/menus/start.c
+++ b/main/menus/start.c
@@ -140,8 +140,12 @@ void menu_start(xQueueHandle buttonQueue, pax_buf_t* pax_buffer, ILI9341* ili934
                 usb_voltage = 0;
             }
             
-            battery_percent = ((battery_voltage - 3.7) * 100) / (4.1 - 3.7);
-            if (battery_percent > 100) battery_percent = 100;
+            if (battery_voltage >= 3.6) {
+                battery_percent = ((battery_voltage - 3.6) * 100) / (4.2 - 3.6);
+                if (battery_percent > 100) battery_percent = 100;
+            } else {
+                battery_percent = 0;
+            }
             
             battery_charging = (usb_voltage > 4.0) && (battery_percent < 100);
             
diff --git a/main/rp2040_updater.c b/main/rp2040_updater.c
index e05663b..41b8896 100644
--- a/main/rp2040_updater.c
+++ b/main/rp2040_updater.c
@@ -47,7 +47,7 @@ void rp2040_updater(RP2040* rp2040, pax_buf_t* pax_buffer, ILI9341* ili9341) {
         restart();
     }
 
-    if (fw_version < 0x02) { // Update required
+    if (fw_version < 0x03) { // Update required
         display_rp2040_update_state(pax_buffer, ili9341, "Starting bootloader...");
         rp2040_reboot_to_bootloader(rp2040);
         esp_restart();
diff --git a/main/webusb.c b/main/webusb.c
new file mode 100644
index 0000000..995fe11
--- /dev/null
+++ b/main/webusb.c
@@ -0,0 +1,117 @@
+#include <stdio.h>
+#include <string.h>
+#include <sdkconfig.h>
+#include <freertos/FreeRTOS.h>
+#include <freertos/task.h>
+#include <freertos/queue.h>
+#include <esp_system.h>
+#include <esp_err.h>
+#include <esp_log.h>
+#include "driver/uart.h"
+#include "hardware.h"
+#include "managed_i2c.h"
+#include "pax_gfx.h"
+#include "ice40.h"
+#include "system_wrapper.h"
+#include "graphics_wrapper.h"
+#include "esp32/rom/crc.h"
+
+void webusb_install_uart() {
+    fflush(stdout);
+    ESP_ERROR_CHECK(uart_driver_install(0, 2048, 0, 0, NULL, 0));
+    uart_config_t uart_config = {
+        .baud_rate  = 921600,
+        .data_bits  = UART_DATA_8_BITS,
+        .parity     = UART_PARITY_DISABLE,
+        .stop_bits  = UART_STOP_BITS_1,
+        .flow_ctrl  = UART_HW_FLOWCTRL_DISABLE,
+        .source_clk = UART_SCLK_APB,
+    };
+    ESP_ERROR_CHECK(uart_param_config(0, &uart_config));
+}
+
+void webusb_uninstall_uart() {
+    uart_driver_delete(0);
+}
+
+bool webusb_read_stdin(uint8_t* buffer, uint32_t len, uint32_t timeout) {
+    int read = uart_read_bytes(0, buffer, len, timeout / portTICK_PERIOD_MS);
+    return (read == len);
+}
+
+bool webusb_uart_sync(uint32_t* length, uint32_t* crc) {
+    uint8_t rx_buffer[4*3];
+    webusb_read_stdin(rx_buffer, sizeof(rx_buffer), 100);
+    if (memcmp(rx_buffer, "WUSB", 4) != 0) return false;
+    memcpy((uint8_t*) length, &rx_buffer[4 * 1], 4);
+    memcpy((uint8_t*) crc, &rx_buffer[4 * 2], 4);
+    return true;
+}
+
+bool webusb_uart_load(uint8_t* buffer, uint32_t length) {
+    return webusb_read_stdin(buffer, length, 3000);
+}
+
+void webusb_uart_mess(const char *mess) {
+    uart_write_bytes(0, mess, strlen(mess));
+}
+
+void webusb_print_status(pax_buf_t* pax_buffer, ILI9341* ili9341, char* message) {
+    pax_noclip(pax_buffer);
+    pax_background(pax_buffer, 0x325aa8);
+    pax_draw_text(pax_buffer, 0xFFFFFFFF, NULL, 18, 0, 20*0, "WebUSB mode");
+    pax_draw_text(pax_buffer, 0xFFFFFFFF, NULL, 18, 0, 20*1, message);
+    ili9341_write(ili9341, pax_buffer->buf);
+}
+
+void webusb_main(xQueueHandle buttonQueue, pax_buf_t* pax_buffer, ILI9341* ili9341) {
+    webusb_install_uart();
+
+    while (true) {
+        webusb_print_status(pax_buffer, ili9341, "Waiting...");
+
+        // 1) Wait for WUSB followed by data length as uint32 and CRC32 of the data as uint32
+        uint32_t length, crc;
+        while (!webusb_uart_sync(&length, &crc)) {
+            webusb_uart_mess("WUSB");
+        }
+
+        webusb_print_status(pax_buffer, ili9341, "Receiving...");
+
+        // 2) Allocate RAM for the data to be received
+        uint8_t* buffer = malloc(length);
+        if (buffer == NULL) {
+            webusb_uart_mess("EMEM");
+            webusb_print_status(pax_buffer, ili9341, "Error: malloc failed");
+            vTaskDelay(100 / portTICK_PERIOD_MS);
+            continue;
+        }
+
+        // 3) Receive data into the buffer
+        if (!webusb_uart_load(buffer, length)) {
+            free(buffer);
+            webusb_uart_mess("ERCV");
+            webusb_print_status(pax_buffer, ili9341, "Error: receive failed");
+            vTaskDelay(100 / portTICK_PERIOD_MS);
+            continue;
+        }
+
+        // 4) Check CRC
+        uint32_t checkCrc = crc32_le(0, buffer, length);
+        
+        if (checkCrc != crc) {
+            free(buffer);
+            webusb_uart_mess("ECRC");
+            webusb_print_status(pax_buffer, ili9341, "Error: CRC invalid");
+            vTaskDelay(100 / portTICK_PERIOD_MS);
+            continue;
+        }
+
+        webusb_uart_mess("OKOK");
+        webusb_print_status(pax_buffer, ili9341, "Packet received");
+
+        // To-do: parse packet
+    }
+    
+    webusb_uninstall_uart();
+}
diff --git a/resources/rp2040_firmware.bin b/resources/rp2040_firmware.bin
index 917aafd..c445a28 100755
Binary files a/resources/rp2040_firmware.bin and b/resources/rp2040_firmware.bin differ