replace printer_to_hid example with printer_to_cdc example

fix printer GET_DEVICE_ID request weird wIndex (interface high, alt low)

1 files changed, 115 insertions, 0 deletions

diff --git a/examples/device/printer_to_cdc/src/main.c b/examples/device/printer_to_cdc/src/main.c
new file mode 100644
index 000000000..aba79025c
--- /dev/null
+++ b/examples/device/printer_to_cdc/src/main.c
@@ -0,0 +1,115 @@
+/*
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2026 Ha Thach (tinyusb.org)
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ *
+ */
+
+/* This example demonstrates a USB Printer + CDC composite device.
+ * Data received on the Printer interface is forwarded to the CDC serial port,
+ * and data received on the CDC serial port is forwarded back to the Printer interface.
+ *
+ * To test:
+ *   1. Flash the device
+ *   2. Open a serial terminal on the CDC port (e.g. /dev/ttyACM0)
+ *   3. Send data to the printer: echo "hello" > /dev/usb/lp0
+ *   4. The data appears on the CDC serial terminal
+ *   5. Type in the serial terminal to send data back through the printer TX
+ */
+
+#include <stdlib.h>
+#include <stdio.h>
+#include <string.h>
+
+#include "bsp/board_api.h"
+#include "tusb.h"
+
+#include "usb_descriptors.h"
+
+// -------------------------------------------------------------------+
+// Tasks
+// -------------------------------------------------------------------+
+
+// Forward data from Printer RX to CDC TX
+static void printer_to_cdc_task(void) {
+  if (tud_printer_read_available() == 0 || !tud_cdc_write_available()) {
+    return;
+  }
+
+  uint8_t buf[64];
+  uint32_t count = tud_printer_read(buf, sizeof(buf));
+  if (count > 0) {
+    tud_cdc_write(buf, count);
+    tud_cdc_write_flush();
+  }
+}
+
+// Forward data from CDC RX to Printer TX
+static void cdc_to_printer_task(void) {
+  if (tud_cdc_available() == 0 || !tud_printer_write_available()) {
+    return;
+  }
+
+  uint8_t buf[64];
+  uint32_t count = tud_cdc_read(buf, sizeof(buf));
+  if (count > 0) {
+    tud_printer_write(buf, count);
+    tud_printer_write_flush();
+  }
+}
+
+int main(void) {
+  board_init();
+  // init device stack on configured roothub port
+  tusb_rhport_init_t dev_init = {.role = TUSB_ROLE_DEVICE, .speed = TUSB_SPEED_AUTO};
+  tusb_init(BOARD_TUD_RHPORT, &dev_init);
+  board_init_after_tusb();
+
+  while (1) {
+    tud_task();             // tinyusb device task
+    printer_to_cdc_task();  // forward printer data to CDC
+    cdc_to_printer_task();  // forward CDC data to printer
+  }
+}
+
+//--------------------------------------------------------------------+
+// Printer callbacks
+//--------------------------------------------------------------------+
+
+void tud_printer_rx_cb(uint8_t itf) {
+  (void)itf;
+}
+
+// IEEE 1284 Device ID: first 2 bytes are big-endian total length (including the 2 length bytes).
+// The rest is the Device ID string using standard abbreviated keys.
+static const char printer_device_id[] =
+  "\x00\x34" // total length = 52 = 0x0034 (big-endian)
+  "MFG:TinyUSB;"
+  "MDL:Printer to CDC;"
+  "CMD:PS;"
+  "CLS:PRINTER;";
+
+TU_VERIFY_STATIC(sizeof(printer_device_id) - 1 == 52, "device ID length mismatch");
+
+uint8_t const *tud_printer_get_device_id_cb(uint8_t itf) {
+  (void)itf;
+  return (uint8_t const *)printer_device_id;
+}