Merge pull request #341 from espressif/feat/cdc_tx

feat(cdc): Added support for large TX transfers

Author: tore-espressif

host/class/cdc/esp_modem_usb_dte/esp_modem_usb.cpp

@@ -1,5 +1,5 @@
 /*
- * SPDX-FileCopyrightText: 2022-2023 Espressif Systems (Shanghai) CO LTD
+ * SPDX-FileCopyrightText: 2022-2025 Espressif Systems (Shanghai) CO LTD
  *
  * SPDX-License-Identifier: Apache-2.0
  */
@@ -162,11 +162,6 @@ class UsbTerminal : public Terminal, private CdcAcmDevice {
         auto *this_terminal = static_cast<UsbTerminal *>(user_ctx);
 
         switch (event->type) {
-        // Notifications like Ring, Rx Carrier indication or Network connection indication are not relevant for USB terminal
-        case CDC_ACM_HOST_NETWORK_CONNECTION:
-        case CDC_ACM_HOST_SERIAL_STATE:
-            ESP_LOGD(TAG, "Ignored USB event %d", event->type);
-            break;
         case CDC_ACM_HOST_DEVICE_DISCONNECTED:
             ESP_LOGW(TAG, "USB terminal disconnected");
             if (this_terminal->on_error) {
@@ -180,8 +175,13 @@ class UsbTerminal : public Terminal, private CdcAcmDevice {
                 this_terminal->on_error(terminal_error::UNEXPECTED_CONTROL_FLOW);
             }
             break;
+        // Notifications like Ring, Rx Carrier indication or Network connection indication are not relevant for USB terminal
+        // Suspend/resume events also ignored
+        case CDC_ACM_HOST_NETWORK_CONNECTION:
+        case CDC_ACM_HOST_SERIAL_STATE:
         default:
-            abort();
+            ESP_LOGD(TAG, "Ignored USB event %d", event->type);
+            break;
         }
     }
     size_t buffer_size;

host/class/cdc/usb_host_cdc_acm/CHANGELOG.md

@@ -8,6 +8,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.1.0/),
 
 ### Added
 - Added global suspend/resume support
+- Added support for transmitting data larger than the configured output buffer size
 
 ## [2.1.1] - 2025-09-24
 

host/class/cdc/usb_host_cdc_acm/cdc_acm_host.c

@@ -961,39 +961,61 @@ static void usb_event_cb(const usb_host_client_event_msg_t *event_msg, void *arg
 
 esp_err_t cdc_acm_host_data_tx_blocking(cdc_acm_dev_hdl_t cdc_hdl, const uint8_t *data, size_t data_len, uint32_t timeout_ms)
 {
-    esp_err_t ret;
+    esp_err_t ret = ESP_OK;
     CDC_ACM_CHECK(cdc_hdl, ESP_ERR_INVALID_ARG);
     cdc_dev_t *cdc_dev = (cdc_dev_t *)cdc_hdl;
     CDC_ACM_CHECK(data && (data_len > 0), ESP_ERR_INVALID_ARG);
     CDC_ACM_CHECK(cdc_dev->data.out_xfer, ESP_ERR_NOT_SUPPORTED); // Device was opened as read-only.
-    CDC_ACM_CHECK(data_len <= cdc_dev->data.out_xfer->data_buffer_size, ESP_ERR_INVALID_SIZE);
 
-    // Take OUT mutex and fill the OUT transfer
-    BaseType_t taken = xSemaphoreTake(cdc_dev->data.out_mux, pdMS_TO_TICKS(timeout_ms));
+    const size_t buffer_size = cdc_dev->data.out_xfer->data_buffer_size;
+    const uint8_t *data_ptr = data;
+    size_t remaining = data_len;
+
+    // Record start time for timeout tracking
+    TickType_t start_ticks = xTaskGetTickCount();
+    TickType_t timeout_ticks = pdMS_TO_TICKS(timeout_ms);
+    TickType_t elapsed_ticks = 0;
+    int remaining_timeout_ticks = timeout_ticks;
+
+    // Take OUT mutex for the entire transfer operation
+    BaseType_t taken = xSemaphoreTake(cdc_dev->data.out_mux, remaining_timeout_ticks);
     if (taken != pdTRUE) {
         return ESP_ERR_TIMEOUT;
     }
 
-    ESP_LOGD(TAG, "Submitting BULK OUT transfer");
     SemaphoreHandle_t transfer_finished_semaphore = (SemaphoreHandle_t)cdc_dev->data.out_xfer->context;
-    xSemaphoreTake(transfer_finished_semaphore, 0); // Make sure the semaphore is taken before we submit new transfer
 
-    memcpy(cdc_dev->data.out_xfer->data_buffer, data, data_len);
-    cdc_dev->data.out_xfer->num_bytes = data_len;
-    cdc_dev->data.out_xfer->timeout_ms = timeout_ms;
-    ESP_GOTO_ON_ERROR(usb_host_transfer_submit(cdc_dev->data.out_xfer), unblock, TAG,);
+    // Process data in chunks if it's larger than the buffer size
+    while (remaining > 0) {
+        size_t chunk_size = (remaining > buffer_size) ? buffer_size : remaining;
+
+        ESP_LOGV(TAG, "Submitting BULK OUT transfer chunk: %zu bytes (remaining: %zu)", chunk_size, remaining);
+        xSemaphoreTake(transfer_finished_semaphore, 0); // Make sure the semaphore is taken before we submit new transfer
+
+        memcpy(cdc_dev->data.out_xfer->data_buffer, data_ptr, chunk_size);
+        cdc_dev->data.out_xfer->num_bytes = chunk_size;
+        // Use remaining timeout for this chunk's transfer timeout
+        cdc_dev->data.out_xfer->timeout_ms = pdTICKS_TO_MS(remaining_timeout_ticks);
+        ESP_GOTO_ON_ERROR(usb_host_transfer_submit(cdc_dev->data.out_xfer), unblock, TAG,);
+
+        // Wait for OUT transfer completion with remaining timeout
+        taken = xSemaphoreTake(transfer_finished_semaphore, remaining_timeout_ticks);
+        elapsed_ticks = xTaskGetTickCount() - start_ticks;
+        remaining_timeout_ticks = timeout_ticks - elapsed_ticks;
+        if (!taken || remaining_timeout_ticks < 0) {
+            cdc_acm_reset_transfer_endpoint(cdc_dev->dev_hdl, cdc_dev->data.out_xfer); // Resetting the endpoint will cause all in-progress transfers to complete
+            ESP_LOGW(TAG, "TX transfer timeout");
+            ret = ESP_ERR_TIMEOUT;
+            goto unblock;
+        }
 
-    // Wait for OUT transfer completion
-    taken = xSemaphoreTake(transfer_finished_semaphore, pdMS_TO_TICKS(timeout_ms));
-    if (!taken) {
-        cdc_acm_reset_transfer_endpoint(cdc_dev->dev_hdl, cdc_dev->data.out_xfer); // Resetting the endpoint will cause all in-progress transfers to complete
-        ESP_LOGW(TAG, "TX transfer timeout");
-        ret = ESP_ERR_TIMEOUT;
-        goto unblock;
+        ESP_GOTO_ON_FALSE(cdc_dev->data.out_xfer->status == USB_TRANSFER_STATUS_COMPLETED, ESP_ERR_INVALID_RESPONSE, unblock, TAG, "Bulk OUT transfer error");
+        ESP_GOTO_ON_FALSE(cdc_dev->data.out_xfer->actual_num_bytes == chunk_size, ESP_ERR_INVALID_RESPONSE, unblock, TAG, "Incorrect number of bytes transferred");
+
+        remaining -= chunk_size;
+        data_ptr += chunk_size;
     }
 
-    ESP_GOTO_ON_FALSE(cdc_dev->data.out_xfer->status == USB_TRANSFER_STATUS_COMPLETED, ESP_ERR_INVALID_RESPONSE, unblock, TAG, "Bulk OUT transfer error");
-    ESP_GOTO_ON_FALSE(cdc_dev->data.out_xfer->actual_num_bytes == data_len, ESP_ERR_INVALID_RESPONSE, unblock, TAG, "Incorrect number of bytes transferred");
     ret = ESP_OK;
 
 unblock:

host/class/cdc/usb_host_cdc_acm/test_app/main/CMakeLists.txt

@@ -5,3 +5,4 @@ idf_component_register(SRC_DIRS .
 
 # So we have access to private_include:
 target_include_directories(${COMPONENT_LIB} PRIVATE "../../")
+target_compile_options(${COMPONENT_LIB} PRIVATE -Wno-missing-field-initializers)

host/class/cdc/usb_host_cdc_acm/test_app/main/test_app_main.c

@@ -1,11 +1,12 @@
 /*
- * SPDX-FileCopyrightText: 2024 Espressif Systems (Shanghai) CO LTD
+ * SPDX-FileCopyrightText: 2024-2025 Espressif Systems (Shanghai) CO LTD
  *
  * SPDX-License-Identifier: Apache-2.0
  */
 
 #include <stdio.h>
 #include <string.h>
+#include "esp_newlib.h"
 #include "unity.h"
 #include "unity_test_runner.h"
 #include "unity_test_utils_memory.h"
@@ -17,6 +18,7 @@ void setUp(void)
 
 void tearDown(void)
 {
+    esp_reent_cleanup();    //clean up some of the newlib's lazy allocations
     unity_utils_evaluate_leaks();
 }
 
@@ -36,6 +38,6 @@ void app_main(void)
     printf("                 \\/         \\/             \\/     \\/        \r\n");
 
     unity_utils_setup_heap_record(80);
-    unity_utils_set_leak_level(530);
+    unity_utils_set_leak_level(30);
     unity_run_menu();
 }