STM32C071 USB Host

[vermas]

I'm looking to implement USB host functionality on an STM32C071 to connect with a single device that sends/receives serial data over USB so the only class I'm interested in is CDC, but I'm having trouble using USBX (I'm not using RTOS).

For now I haven't used and read/write functions, my goal was to start by checking the functionality of the callbacks inside "app_usbx_host.c" which are: device inserted/removed/connected/disconnected, enumeration fail and no USB device found. Each one sets a different flag to be handled inside the main loop.

I put a breakpoint inside the USB IRQ and when I connect the USB device it stops execution and confirms the breakpoint has been reached, however none of my flags are ever set,.

I suspect the reason might be because I haven't done anything to link the USB peripheral to the USBX stack, if the function responsible for that is ux_host_stack_hcd_register, I have no idea how to use it. The function prototype is:

UINT _ux_host_stack_hcd_register(UCHAR *hcd_name, UINT (*hcd_init_function)(struct UX_HCD_STRUCT *), ULONG hcd_param1, ULONG hcd_param2);

I'm completely lost in the description for each of the arguments.

My main.c is basically this:

#include "main.h"
#include "app_usbx_host.h"

#include <stdio.h>
#include <string.h>

UART_HandleTypeDef huart1;
HCD_HandleTypeDef hhcd_USB_DRD_FS;

uint8_t my_TX_buffer[64];
uint8_t my_RX_buffer[64];
uint16_t written_len;

// THESE ARE THE FLAGS (NOT) BEING SET INSIDE THE CALLBACKS IN "app_usbx_host.c"
extern char DEVICE_INSERTED;
extern char DEVICE_REMOVED;
extern char DEVICE_CONNECTED;
extern char DEVICE_DISCONNECTED;
extern char ENUMERATION_FAIL;
extern char NOTHING_CONNECTED;

void SystemClock_Config(void);
static void MX_USART1_UART_Init(void);
static void MX_USB_HCD_Init(void);

int main(void){

  HAL_Init();
  SystemClock_Config();
  MX_USART1_UART_Init();
  MX_USB_HCD_Init();
  MX_USBX_Host_Init();
  HAL_HCD_Start(&hhcd_USB_DRD_FS);

  while (1){

   ux_system_tasks_run();

   if (DEVICE_INSERTED){
   written_len = snprintf((char *) my_TX_buffer, sizeof(my_TX_buffer), "USB Device Inserted\r\n");
   HAL_UART_Transmit(&huart1, my_TX_buffer, written_len, 100);
   DEVICE_INSERTED = 0;
   }
   
   // REST OMITTED, all the other flags get treated in the same way here   
  }
}

void SystemClock_Config(void){
  // OMITTED FOR CLARITY
}

static void MX_USART1_UART_Init(void){
  // OMITTED, UART IS WORKING
}

static void MX_USB_HCD_Init(void){
  hhcd_USB_DRD_FS.Instance = USB_DRD_FS;
  hhcd_USB_DRD_FS.Init.dev_endpoints = 8;
  hhcd_USB_DRD_FS.Init.Host_channels = 8;
  hhcd_USB_DRD_FS.Init.speed = USBD_FS_SPEED;
  hhcd_USB_DRD_FS.Init.phy_itface = HCD_PHY_EMBEDDED;
  hhcd_USB_DRD_FS.Init.Sof_enable = DISABLE;
  hhcd_USB_DRD_FS.Init.low_power_enable = DISABLE;
  hhcd_USB_DRD_FS.Init.vbus_sensing_enable = DISABLE;
  hhcd_USB_DRD_FS.Init.bulk_doublebuffer_enable = DISABLE;
  hhcd_USB_DRD_FS.Init.iso_singlebuffer_enable = DISABLE;
  if (HAL_HCD_Init(&hhcd_USB_DRD_FS) != HAL_OK) Error_Handler();
}

void Error_Handler(void){
  __disable_irq();
  while (1){}
}

#ifdef USE_FULL_ASSERT
void assert_failed(uint8_t *file, uint32_t line){}
#endif /* USE_FULL_ASSERT */

I don't remember making significant changes to any other file apart from creating the flags inside app_usbx_host.c.

The images below contain the CubeMX settings I used.

USB peripheral configuration

Class configuration

USBX configuration

I'd be extremely grateful if anyone could tell me what I missed.

---

Edited to apply proper source code formatting - please see How to insert source code for future reference.

[Pavel A.]

> I put a breakpoint inside the USB IRQ

USB is time-sensitive. Delays caused by breakpoints can confuse the device. Debug using non-blocking methods. USB bus analyzer can help too.

[FBL]

Hi @vermas 

You need to ensure initialization the USBX host stack, ensure it has enough memory, and poll its task function in the main loop. MX_USBX_Host_Init() must be called after MX_USB_HCD_Init() so the USBX host stack can properly register and link to the USB peripheral.

MX_USB_HCD_Init();        // Initialize the USB host controller
MX_USBX_Host_Init();      // Then initialize the USBX host stack

In your main loop, you also need to call ux_system_tasks_run(); and poll on your CDC task.

As a reference, start from this official example and then adapt/port it to your standalone application.

If still having issues, don't hesitate to share your project.