Added dev_cdc example

README.md

@@ -440,6 +440,16 @@ At the time of writing, there is only one dual example available:
 
 - tinyusb_dual_host_hid_to_device_cdc
 
+### Custom CDC with SDK stdio
+
+This example demonstrates how to use the TinyUSB CDC device library to create two USB serial ports, and assign one of them to the SDK for stdio.
+
+App|Description
+---|---
+[dev_cdc](usb/device/dev_cdc) | A USB CDC device example with two serial ports, one of which is used for stdio
+
+The example exposes two serial ports over USB to the host. The first port is used for stdio, and the second port is used for a simple echo loopback. You can connect to the second port and send some characters, and they will be echoed back on the first port while you will receive a "OK\r\n" message on the second port indicating that the data was received.
+
 ### Watchdog
 
 App|Description

usb/device/CMakeLists.txt

@@ -6,5 +6,6 @@ set(TINYUSB_LWIP_PATH ${PICO_LWIP_PATH})
 # Some examples use this, and we need to set this here due to a bug in the TinyUSB CMake config
 set(TOP ${PICO_TINYUSB_PATH})
 add_subdirectory(${PICO_TINYUSB_PATH}/examples/device tinyusb_device_examples)
+add_subdirectory_exclude_platforms(dev_cdc)
 add_subdirectory_exclude_platforms(dev_hid_composite)
 add_subdirectory_exclude_platforms(dev_lowlevel)

usb/device/dev_cdc/CMakeLists.txt

@@ -0,0 +1,22 @@
+cmake_minimum_required(VERSION 3.13)
+
+add_executable(dev_cdc)
+
+target_sources(dev_cdc PUBLIC
+        ${CMAKE_CURRENT_LIST_DIR}/main.c
+        ${CMAKE_CURRENT_LIST_DIR}/usb_descriptors.c
+        )
+
+# Make sure TinyUSB can find tusb_config.h
+target_include_directories(dev_cdc PUBLIC
+        ${CMAKE_CURRENT_LIST_DIR})
+
+# In addition to pico_stdlib required for common PicoSDK functionality, add dependency on tinyusb_device
+# for TinyUSB device support and tinyusb_board for the additional board support library used by the example
+target_link_libraries(dev_cdc PUBLIC pico_stdlib pico_unique_id tinyusb_device tinyusb_board)
+
+pico_enable_stdio_usb(dev_cdc 1)
+pico_add_extra_outputs(dev_cdc)
+
+# add url via pico_set_program_url
+example_auto_set_url(dev_cdc)

usb/device/dev_cdc/main.c

@@ -0,0 +1,74 @@
+#include <stdlib.h>
+#include <bsp/board_api.h>
+#include <tusb.h>
+
+#include <pico/stdio.h>
+
+void custom_cdc_task(void);
+
+int main(void)
+{
+    // Initialize TinyUSB stack
+    board_init();
+    tusb_init();
+
+    // TinyUSB board init callback after init
+    if (board_init_after_tusb) {
+        board_init_after_tusb();
+    }
+
+    // let pico sdk use the first cdc interface for std io
+    stdio_init_all();
+
+    // main run loop
+    while (1) {
+        // TinyUSB device task | must be called regurlarly
+        tud_task();
+
+        // custom tasks
+        custom_cdc_task();
+    }
+
+    // indicate no error
+    return 0;
+}
+
+void custom_cdc_task(void)
+{
+    // polling CDC interfaces if wanted
+
+    // Check if CDC interface 0 (for pico sdk stdio) is connected and ready
+
+    if (tud_cdc_n_connected(0)) {
+        // print on CDC 0 some debug message
+        printf("Connected to CDC 0\n");
+        sleep_ms(5000); // wait for 5 seconds
+    }
+}
+
+// callback when data is received on a CDC interface
+void tud_cdc_rx_cb(uint8_t itf)
+{
+    // allocate buffer for the data in the stack
+    uint8_t buf[CFG_TUD_CDC_RX_BUFSIZE];
+
+    printf("RX CDC %d\n", itf);
+
+    // read the available data 
+    // | IMPORTANT: also do this for CDC0 because otherwise
+    // | you won't be able to print anymore to CDC0
+    // | next time this function is called
+    uint32_t count = tud_cdc_n_read(itf, buf, sizeof(buf));
+
+    // check if the data was received on the second cdc interface
+    if (itf == 1) {
+        // process the received data
+        buf[count] = 0; // null-terminate the string
+        // now echo data back to the console on CDC 0
+        printf("Received on CDC 1: %s\n", buf);
+
+        // and echo back OK on CDC 1
+        tud_cdc_n_write(itf, (uint8_t const *) "OK\r\n", 4);
+        tud_cdc_n_write_flush(itf);
+    }
+}

usb/device/dev_cdc/tusb_config.h

@@ -0,0 +1,42 @@
+// TODO: why not #pragma once?
+
+#ifndef _TUSB_CONFIG_H_
+#define _TUSB_CONFIG_H_
+
+#ifdef __cplusplus
+ extern "C" {
+#endif
+
+#define CFG_TUSB_MCU            (OPT_MCU_RP2040)
+#define CFG_TUSB_OS             (OPT_OS_PICO)
+#define CFG_TUSB_DEBUG          (0)
+
+#define CFG_TUD_ENABLED         (1)
+
+// Legacy RHPORT configuration
+#define CFG_TUSB_RHPORT0_MODE   (OPT_MODE_DEVICE | OPT_MODE_FULL_SPEED)
+#ifndef BOARD_TUD_RHPORT
+#define BOARD_TUD_RHPORT        (0)
+#endif
+// end legacy RHPORT
+
+//------------------------
+// DEVICE CONFIGURATION //
+//------------------------
+
+// Enable 2 CDC classes
+#define CFG_TUD_CDC             (2)
+// Set CDC FIFO buffer sizes
+#define CFG_TUD_CDC_RX_BUFSIZE  (64)
+#define CFG_TUD_CDC_TX_BUFSIZE  (64)
+#define CFG_TUD_CDC_EP_BUFSIZE  (64)
+
+#ifndef CFG_TUD_ENDPOINT0_SIZE
+#define CFG_TUD_ENDPOINT0_SIZE  (64)
+#endif
+
+#ifdef __cplusplus
+ }
+#endif
+
+#endif /* _TUSB_CONFIG_H_ */

usb/device/dev_cdc/usb_descriptors.c

@@ -0,0 +1,195 @@
+#include <tusb.h>
+#include <bsp/board_api.h>
+
+// set some example Vendor and Product ID
+// the board will use to identify at the host
+#define _PID_MAP(itf, n)  ( (CFG_TUD_##itf) << (n) )
+#define CDC_EXAMPLE_VID     0xCafe
+// use _PID_MAP to generate unique PID for each interface
+#define CDC_EXAMPLE_PID     (0x4000 | _PID_MAP(CDC, 0))
+// set USB 2.0
+#define CDC_EXAMPLE_BCD     0x0200
+
+// defines a descriptor that will be communicated to the host
+tusb_desc_device_t const desc_device = {
+    .bLength = sizeof(tusb_desc_device_t),
+    .bDescriptorType = TUSB_DESC_DEVICE,
+    .bcdUSB = CDC_EXAMPLE_BCD,
+
+    .bDeviceClass = TUSB_CLASS_MISC, // CDC is a subclass of misc
+    .bDeviceSubClass = MISC_SUBCLASS_COMMON, // CDC uses common subclass
+    .bDeviceProtocol = MISC_PROTOCOL_IAD, // CDC uses IAD
+
+    .bMaxPacketSize0 = CFG_TUD_ENDPOINT0_SIZE, // 64 bytes
+
+    .idVendor = CDC_EXAMPLE_VID,
+    .idProduct = CDC_EXAMPLE_PID,
+    .bcdDevice = 0x0100, // Device release number
+
+    .iManufacturer = 0x01, // Index of manufacturer string
+    .iProduct = 0x02, // Index of product string
+    .iSerialNumber = 0x03, // Index of serial number string
+
+    .bNumConfigurations = 0x01 // 1 configuration
+};
+
+// called when host requests to get device descriptor
+uint8_t const *tud_descriptor_device_cb(void);
+
+enum {
+    ITF_NUM_CDC_0 = 0,
+    ITF_NUM_CDC_0_DATA,
+    ITF_NUM_CDC_1,
+    ITF_NUM_CDC_1_DATA,
+    ITF_NUM_TOTAL
+};
+
+// total length of configuration descriptor
+#define CONFIG_TOTAL_LEN    (TUD_CONFIG_DESC_LEN + CFG_TUD_CDC * TUD_CDC_DESC_LEN)
+
+// define endpoint numbers
+#define EPNUM_CDC_0_NOTIF   0x81 // notification endpoint for CDC 0
+#define EPNUM_CDC_0_OUT     0x02 // out endpoint for CDC 0
+#define EPNUM_CDC_0_IN      0x82 // in endpoint for CDC 0
+
+#define EPNUM_CDC_1_NOTIF   0x84 // notification endpoint for CDC 1
+#define EPNUM_CDC_1_OUT     0x05 // out endpoint for CDC 1
+#define EPNUM_CDC_1_IN      0x85 // in endpoint for CDC 1
+
+// configure descriptor (for 2 CDC interfaces)
+uint8_t const desc_configuration[] = {
+    // config descriptor | how much power in mA, count of interfaces, ...
+    TUD_CONFIG_DESCRIPTOR(1, ITF_NUM_TOTAL, 0, CONFIG_TOTAL_LEN, 0x80, 100),
+
+    // CDC 0: Communication Interface - TODO: get 64 from tusb_config.h
+    TUD_CDC_DESCRIPTOR(ITF_NUM_CDC_0, 4, EPNUM_CDC_0_NOTIF, 8, EPNUM_CDC_0_OUT, EPNUM_CDC_0_IN, 64),
+    // CDC 0: Data Interface
+    //TUD_CDC_DESCRIPTOR(ITF_NUM_CDC_0_DATA, 4, 0x01, 0x02),
+
+    // CDC 1: Communication Interface - TODO: get 64 from tusb_config.h
+    TUD_CDC_DESCRIPTOR(ITF_NUM_CDC_1, 4, EPNUM_CDC_1_NOTIF, 8, EPNUM_CDC_1_OUT, EPNUM_CDC_1_IN, 64),
+    // CDC 1: Data Interface
+    //TUD_CDC_DESCRIPTOR(ITF_NUM_CDC_1_DATA, 4, 0x03, 0x04),
+};
+
+// called when host requests to get configuration descriptor
+uint8_t const * tud_descriptor_configuration_cb(uint8_t index);
+
+// more device descriptor this time the qualifier
+tusb_desc_device_qualifier_t const desc_device_qualifier = {
+    .bLength = sizeof(tusb_desc_device_t),
+    .bDescriptorType = TUSB_DESC_DEVICE,
+    .bcdUSB = CDC_EXAMPLE_BCD,
+
+    .bDeviceClass = TUSB_CLASS_CDC,
+    .bDeviceSubClass = MISC_SUBCLASS_COMMON,
+    .bDeviceProtocol = MISC_PROTOCOL_IAD,
+
+    .bMaxPacketSize0 = CFG_TUD_ENDPOINT0_SIZE,
+    .bNumConfigurations = 0x01,
+    .bReserved = 0x00
+};
+
+// called when host requests to get device qualifier descriptor
+uint8_t const* tud_descriptor_device_qualifier_cb(void);
+
+// String descriptors referenced with .i... in the descriptor tables
+
+enum {
+    STRID_LANGID = 0,   // 0: supported language ID
+    STRID_MANUFACTURER, // 1: Manufacturer
+    STRID_PRODUCT,      // 2: Product
+    STRID_SERIAL,       // 3: Serials
+    STRID_CDC_0,        // 4: CDC Interface 0
+    STRID_CDC_1,        // 5: CDC Interface 1
+};
+
+// array of pointer to string descriptors
+char const *string_desc_arr[] = {
+    // switched because board is little endian
+    (const char[]) { 0x09, 0x04 },  // 0: supported language is English (0x0409)
+    "Raspberry Pi",                 // 1: Manufacturer
+    "Pico (2)",                     // 2: Product
+    NULL,                           // 3: Serials (null so it uses unique ID if available)
+    "Pico SDK stdio"                // 4: CDC Interface 0
+    "Custom CDC",                   // 5: CDC Interface 1,
+    "RPiReset"                      // 6: Reset Interface
+};
+
+// buffer to hold the string descriptor during the request | plus 1 for the null terminator
+static uint16_t _desc_str[32 + 1];
+
+// called when host request to get string descriptor
+uint16_t const *tud_descriptor_string_cb(uint8_t index, uint16_t langid);
+
+// --------------------------------------------------------------------+
+// IMPLEMENTATION
+// --------------------------------------------------------------------+
+
+uint8_t const *tud_descriptor_device_cb(void)
+{
+    return (uint8_t const *)&desc_device;
+}
+
+uint8_t const* tud_descriptor_device_qualifier_cb(void)
+{
+    return (uint8_t const *)&desc_device_qualifier;
+}
+
+uint8_t const * tud_descriptor_configuration_cb(uint8_t index)
+{
+    // avoid unused parameter warning and keep function signature consistent
+    (void)index;
+
+    return desc_configuration;
+}
+
+uint16_t const *tud_descriptor_string_cb(uint8_t index, uint16_t langid)
+{
+    // TODO: check lang id
+    (void) langid;
+    size_t char_count;
+
+    // Determine which string descriptor to return
+    switch (index) {
+        case STRID_LANGID:
+            memcpy(&_desc_str[1], string_desc_arr[STRID_LANGID], 2);
+            char_count = 1;
+            break;
+
+        case STRID_SERIAL:
+            // try to read the serial from the board
+            char_count = board_usb_get_serial(_desc_str + 1, 32);
+            break;
+
+        default:
+            // COPYRIGHT NOTE: Based on TinyUSB example
+            // Windows wants utf16le
+
+            // Determine which string descriptor to return
+            if ( !(index < sizeof(string_desc_arr) / sizeof(string_desc_arr[0])) ) {
+                return NULL;
+            }
+
+            // Copy string descriptor into _desc_str
+            const char *str = string_desc_arr[index];
+
+            char_count = strlen(str);
+            size_t const max_count = sizeof(_desc_str) / sizeof(_desc_str[0]) - 1; // -1 for string type
+            // Cap at max char
+            if (char_count > max_count) {
+                char_count = max_count;
+            }
+
+            // Convert ASCII string into UTF-16
+            for (size_t i = 0; i < char_count; i++) {
+                _desc_str[1 + i] = str[i];
+            }
+            break;
+    }
+
+    // First byte is the length (including header), second byte is string type
+    _desc_str[0] = (uint16_t) ((TUSB_DESC_STRING << 8) | (char_count * 2 + 2));
+
+    return _desc_str;
+}