feat: Add support for communication via CP210x and CH34x serial converters

Extends USB serial flashing beyond CDC ACM to support CP210x (Silicon Labs)
and CH34x (WinChipHead) serial converters, enabling flashing through
most common USB-to-serial bridge chips.

Author: Dzarda7

examples/esp32_usb_cdc_acm_example/main/main.c

@@ -20,9 +20,6 @@
 #include "usb/usb_host.h"
 #include "usb/cdc_acm_host.h"
 
-#define ESPRESSIF_VID 0x303a
-#define ESP_SERIAL_JTAG_PID 0x1001
-
 static const char *TAG = "usb_flasher";
 static SemaphoreHandle_t device_disconnected_sem;
 
@@ -81,8 +78,8 @@ void app_main(void)
 
     while (true) {
         const loader_esp32_usb_cdc_acm_config_t config = {
-            .device_vid = ESPRESSIF_VID,
-            .device_pid = ESP_SERIAL_JTAG_PID,
+            .device_vid = USB_VID_PID_AUTO_DETECT,
+            .device_pid = USB_VID_PID_AUTO_DETECT,
             .connection_timeout_ms = 1000,
             .out_buffer_size = 4096,
             .device_disconnected_callback = device_disconnected_callback,

idf_component.yml

@@ -8,3 +8,13 @@ dependencies:
     rules:
       - if: "idf_version >=4.4"
       - if: "target in [esp32s2, esp32s3, esp32p4]"
+  usb_host_cp210x_vcp:
+    version: "^2.2"
+    rules:
+      - if: "idf_version >=4.4"
+      - if: "target in [esp32s2, esp32s3, esp32p4]"
+  usb_host_ch34x_vcp:
+    version: "^2.2"
+    rules:
+      - if: "idf_version >=4.4"
+      - if: "target in [esp32s2, esp32s3, esp32p4]"

port/esp32_usb_cdc_acm_port.c

@@ -17,10 +17,12 @@
 #include <stdio.h>
 #include "esp_log.h"
 #include "esp_timer.h"
+#include "usb/cdc_acm_host.h"
+#include "usb/vcp_cp210x.h"
+#include "usb/vcp_ch34x.h"
+#include "esp_loader_io.h"
 #include "esp32_usb_cdc_acm_port.h"
 
-#define ESP_SERIAL_JTAG_PID 0x1001
-
 static const char *TAG = "usb_cdc_acm_port";
 
 static cdc_acm_dev_hdl_t s_acm_device;
@@ -104,18 +106,18 @@ static void usb_serial_jtag_enter_booloader(void)
 static void usb_serial_converter_reset_target(void)
 {
     xStreamBufferReset(s_rx_stream_buffer);
-    cdc_acm_host_set_control_line_state(s_acm_device, true, true);
+    cdc_acm_host_set_control_line_state(s_acm_device, false, true);
     loader_port_delay_ms(SERIAL_FLASHER_RESET_HOLD_TIME_MS);
-    cdc_acm_host_set_control_line_state(s_acm_device, true, false);
+    cdc_acm_host_set_control_line_state(s_acm_device, false, false);
 }
 
 static void usb_serial_converter_enter_bootloader(void)
 {
-    cdc_acm_host_set_control_line_state(s_acm_device, true, false);
-
-    usb_serial_converter_reset_target();
-
+    xStreamBufferReset(s_rx_stream_buffer);
+    cdc_acm_host_set_control_line_state(s_acm_device, false, true);
     loader_port_delay_ms(SERIAL_FLASHER_BOOT_HOLD_TIME_MS);
+    cdc_acm_host_set_control_line_state(s_acm_device, true, false);
+    loader_port_delay_ms(SERIAL_FLASHER_RESET_HOLD_TIME_MS);
     cdc_acm_host_set_control_line_state(s_acm_device, false, false);
 }
 
@@ -169,11 +171,6 @@ esp_loader_error_t loader_port_esp32_usb_cdc_acm_init(const loader_esp32_usb_cdc
     s_device_disconnected_callback = config->device_disconnected_callback;
     s_acm_host_serial_state_callback = config->acm_host_serial_state_callback;
 
-    /* Different reset and enter bootloader sequences are needed depending on whether the target
-     * device is connected via internal USB Serial/JTAG or an USB to serial converter which
-     * connects to target UART and BOOT/RST pins. See pages 1207 and 1208 of the ESP32-S3 TRM */
-    s_is_usb_serial_jtag = config->device_pid == ESP_SERIAL_JTAG_PID;
-
     s_rx_stream_buffer = xStreamBufferCreate(1024, 1);
 
     if (s_rx_stream_buffer == NULL) {
@@ -189,20 +186,42 @@ esp_loader_error_t loader_port_esp32_usb_cdc_acm_init(const loader_esp32_usb_cdc
         .data_cb = handle_usb_data
     };
 
-    esp_err_t err = cdc_acm_host_open(config->device_vid,
-                                      config->device_pid,
-                                      0,
-                                      &dev_config,
-                                      &s_acm_device);
+    const bool auto_detect = (config->device_vid == USB_VID_PID_AUTO_DETECT ||
+                              config->device_pid == USB_VID_PID_AUTO_DETECT);
 
-    if (err != ESP_OK) {
-        ESP_LOGE(TAG, "Failed to open the USB device");
-        esp_loader_error_t deinit_status = loader_port_esp32_usb_cdc_acm_deinit();
-        assert(deinit_status == ESP_LOADER_SUCCESS);
-        return ESP_LOADER_ERROR_FAIL;
+    if (auto_detect) {
+        if (cdc_acm_host_open(ESPRESSIF_VID, ESP_SERIAL_JTAG_PID, 0, &dev_config, &s_acm_device) == ESP_OK) {
+            s_is_usb_serial_jtag = true;
+            return ESP_LOADER_SUCCESS;
+        }
+        if (cp210x_vcp_open(CP210X_PID_AUTO, 0, &dev_config, &s_acm_device) == ESP_OK) {
+            s_is_usb_serial_jtag = false;
+            return ESP_LOADER_SUCCESS;
+        }
+        if (ch34x_vcp_open(CH34X_PID_AUTO, 0, &dev_config, &s_acm_device) == ESP_OK) {
+            s_is_usb_serial_jtag = false;
+            return ESP_LOADER_SUCCESS;
+        }
+    } else {
+        esp_err_t err;
+        if (config->device_vid == SILICON_LABS_VID) {
+            err = cp210x_vcp_open(config->device_pid, 0, &dev_config, &s_acm_device);
+        } else if (config->device_vid == NANJING_QINHENG_MICROE_VID) {
+            err = ch34x_vcp_open(config->device_pid, 0, &dev_config, &s_acm_device);
+        } else {
+            err = cdc_acm_host_open(config->device_vid, config->device_pid, 0, &dev_config, &s_acm_device);
+        }
+
+        if (err == ESP_OK) {
+            s_is_usb_serial_jtag = (config->device_vid == ESPRESSIF_VID);
+            return ESP_LOADER_SUCCESS;
+        }
     }
 
-    return ESP_LOADER_SUCCESS;
+    ESP_LOGE(TAG, "Failed to open any USB device");
+    esp_loader_error_t deinit_status = loader_port_esp32_usb_cdc_acm_deinit();
+    assert(deinit_status == ESP_LOADER_SUCCESS);
+    return ESP_LOADER_ERROR_FAIL;
 }
 
 

port/esp32_usb_cdc_acm_port.h

@@ -15,7 +15,7 @@
 
 #pragma once
 
-#include "esp_loader_io.h"
+#include "esp_loader.h"
 #include "usb/usb_host.h"
 #include "usb/cdc_acm_host.h"
 #include "freertos/stream_buffer.h"
@@ -24,6 +24,23 @@
 extern "C" {
 #endif
 
+#define USB_VID_PID_AUTO_DETECT     (0)      // Use for VID/PID in config to enable auto-detection
+
+#define ESPRESSIF_VID               (0x303a)
+#define ESP_SERIAL_JTAG_PID         (0x1001)
+
+// VID and PID definitions from esp-usb library, only these are supported
+#define SILICON_LABS_VID            (0x10C4) // Silicon Labs
+#define CP210X_PID                  (0xEA60) // Single i.e. CP2101 - CP2104
+#define CP2105_PID                  (0xEA70) // Dual
+#define CP2108_PID                  (0xEA71) // Quad
+
+#define NANJING_QINHENG_MICROE_VID  (0x1A86) // Nanjing Qinheng Microelectronics
+#define CH340_PID                   (0x7522)
+#define CH340_PID_1                 (0x7523)
+#define CH341_PID                   (0x5523)
+
+
 typedef void (*loader_port_esp32_usb_cdc_acm_callback_t) (void);
 
 typedef struct {