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Add reset interface to multi CDC example #694

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Add reset interface to multi CDC example #694

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6a9478b
Add reset interface to dev_multi_cdc example
will-v-pi Aug 5, 2025
fab1c8b
Prevent custom task blocking tud_task for 5s every time
will-v-pi Aug 6, 2025
8c8faeb
Increment PID to prevent issues with existing uses of the example
will-v-pi Aug 6, 2025
82e2c14
Header rename & comments
will-v-pi Aug 15, 2025
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9 changes: 9 additions & 0 deletions usb/device/dev_multi_cdc/CMakeLists.txt
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Original file line number Diff line number Diff line change
Expand Up @@ -11,6 +11,15 @@ target_sources(dev_multi_cdc PUBLIC
target_include_directories(dev_multi_cdc PUBLIC
${CMAKE_CURRENT_LIST_DIR})

# Enable the reset interface
target_compile_definitions(dev_multi_cdc PUBLIC
PICO_STDIO_USB_ENABLE_RESET_VIA_VENDOR_INTERFACE=1
# use SDK MS_OS_20 descriptor, as this doesn't have a custom one
PICO_STDIO_USB_RESET_INTERFACE_SUPPORT_MS_OS_20_DESCRIPTOR=1
# pass the interface number to the SDK MS_OS_20 descriptor
PICO_STDIO_USB_RESET_INTERFACE_MS_OS_20_DESCRIPTOR_ITF=4
)

# 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_multi_cdc PUBLIC pico_stdlib pico_unique_id tinyusb_device tinyusb_board)
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17 changes: 13 additions & 4 deletions usb/device/dev_multi_cdc/main.c
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Expand Up @@ -9,9 +9,15 @@
#include <tusb.h>

#include <pico/stdio.h>
#include <pico/stdlib.h>

void custom_cdc_task(void);

bool tud_task_callback(__unused struct repeating_timer *t) {
tud_task();
return true;
}

int main(void)
{
// Initialize TinyUSB stack
Expand All @@ -26,15 +32,18 @@ int main(void)
// let pico sdk use the first cdc interface for std io
stdio_init_all();

// TinyUSB device task must be called regularly, so we use a repeating timer
struct repeating_timer timer;
add_repeating_timer_ms(1, tud_task_callback, NULL, &timer);

// main run loop
while (1) {
// TinyUSB device task | must be called regurlarly
tud_task();

// custom tasks
// custom tasks can run in the main loop without blocking the TinyUSB task
custom_cdc_task();
}

cancel_repeating_timer(&timer);

// indicate no error
return 0;
}
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73 changes: 41 additions & 32 deletions usb/device/dev_multi_cdc/usb_descriptors.c
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Original file line number Diff line number Diff line change
Expand Up @@ -7,14 +7,40 @@
#include <tusb.h>
#include <bsp/board_api.h>

#include "pico/usb_reset_interface_device.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
#define CDC_EXAMPLE_PID (0x4100 | _PID_MAP(CDC, 0))
// set to 2.10 so the MS_OS_20_DESCRIPTOR works
#define CDC_EXAMPLE_BCD 0x0210

// 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
STRID_RPI_RESET, // 6: Reset Interface
};

// 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,
"Reset" // 6: Reset Interface
};

// defines a descriptor that will be communicated to the host
tusb_desc_device_t const desc_device = {
Expand All @@ -32,9 +58,9 @@ tusb_desc_device_t const desc_device = {
.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
.iManufacturer = STRID_MANUFACTURER, // Index of manufacturer string
.iProduct = STRID_PRODUCT, // Index of product string
.iSerialNumber = STRID_SERIAL, // Index of serial number string

.bNumConfigurations = 0x01 // 1 configuration
};
Expand All @@ -47,11 +73,14 @@ enum {
ITF_NUM_CDC_0_DATA,
ITF_NUM_CDC_1,
ITF_NUM_CDC_1_DATA,
ITF_NUM_RPI_RESET,
ITF_NUM_TOTAL
};

static_assert(ITF_NUM_RPI_RESET == PICO_STDIO_USB_RESET_INTERFACE_MS_OS_20_DESCRIPTOR_ITF, "ITF_NUM_RPI_RESET must be equal to the PICO_STDIO_USB_RESET_INTERFACE_MS_OS_20_DESCRIPTOR_ITF set in CMakeLists.txt");

// total length of configuration descriptor
#define CONFIG_TOTAL_LEN (TUD_CONFIG_DESC_LEN + CFG_TUD_CDC * TUD_CDC_DESC_LEN)
#define CONFIG_TOTAL_LEN (TUD_CONFIG_DESC_LEN + CFG_TUD_CDC * TUD_CDC_DESC_LEN + TUD_RPI_RESET_DESC_LEN)

// define endpoint numbers
#define EPNUM_CDC_0_NOTIF 0x81 // notification endpoint for CDC 0
Expand All @@ -68,14 +97,17 @@ uint8_t const desc_configuration[] = {
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),
TUD_CDC_DESCRIPTOR(ITF_NUM_CDC_0, STRID_CDC_0, 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),
TUD_CDC_DESCRIPTOR(ITF_NUM_CDC_1, STRID_CDC_1, 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),

// RPi Reset Interface
TUD_RPI_RESET_DESCRIPTOR(ITF_NUM_RPI_RESET, STRID_RPI_RESET),
};

// called when host requests to get configuration descriptor
Expand All @@ -99,29 +131,6 @@ tusb_desc_device_qualifier_t const desc_device_qualifier = {
// 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];

Expand Down
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