Reputation: 103
What is issue with STM32 Virtual Com Port? I can not open it
I have Nucleo STM32H743ZI board. I'm using CubeMX HAL (I tried several versions) and TrueStudio. "Virtual COM port" appearances in Windows 10 (I tried default Windows driver and ST driver) but I can not open port. My C# program write me "The parameter is incorrect" when I try open it:
SerialPort port = new SerialPort("COM8", 9600, Parity.None, 8, StopBits.One);
port.Open(); // System.IO.IOException: 'The parameter is incorrect.'
same message writes me program Realterm, PuTTY do nothing and "Tera Term" program works correct - I can send and receive data to my MCU program.
May anyone know what is it?
In my C# program and in terminal programs I use same parameters
USB Device viewer information:
[Port1] : STMicroelectronics Virtual COM Port
Is Port User Connectable: yes
Is Port Debug Capable: no
Companion Port Number: 17
Companion Hub Symbolic Link Name: USB#ROOT_HUB30#4&2f29167c&0&0#{f18a0e88-c30c-11d0-8815-00a0c906bed8}
Protocols Supported:
USB 1.1: yes
USB 2.0: yes
USB 3.0: no
Device Power State: PowerDeviceD0
---===>Device Information<===---
English product name: "STM32 Virtual ComPort"
ConnectionStatus:
Current Config Value: 0x01 -> Device Bus Speed: Full (is not SuperSpeed or higher capable)
Device Address: 0x0A
Open Pipes: 3
===>Device Descriptor<===
bLength: 0x12
bDescriptorType: 0x01
bcdUSB: 0x0200
bDeviceClass: 0x02 -> This is a Communication Device
bDeviceSubClass: 0x00
bDeviceProtocol: 0x00
bMaxPacketSize0: 0x40 = (64) Bytes
idVendor: 0x0483 = STMicroelectronics
idProduct: 0x5740
bcdDevice: 0x0200
iManufacturer: 0x01
English (United States) "STMicroelectronics"
iProduct: 0x02
English (United States) "STM32 Virtual ComPort"
iSerialNumber: 0x03
English (United States) "354BB9433137"
bNumConfigurations: 0x01
---===>Open Pipes<===---
===>Endpoint Descriptor<===
bLength: 0x07
bDescriptorType: 0x05
bEndpointAddress: 0x82 -> Direction: IN - EndpointID: 2
bmAttributes: 0x03 -> Interrupt Transfer Type
wMaxPacketSize: 0x0008 = 0x08 bytes
bInterval: 0x10
===>Endpoint Descriptor<===
bLength: 0x07
bDescriptorType: 0x05
bEndpointAddress: 0x01 -> Direction: OUT - EndpointID: 1
bmAttributes: 0x02 -> Bulk Transfer Type
wMaxPacketSize: 0x0040 = 0x40 bytes
bInterval: 0x00
===>Endpoint Descriptor<===
bLength: 0x07
bDescriptorType: 0x05
bEndpointAddress: 0x81 -> Direction: IN - EndpointID: 1
bmAttributes: 0x02 -> Bulk Transfer Type
wMaxPacketSize: 0x0040 = 0x40 bytes
bInterval: 0x00
---===>Full Configuration Descriptor<===---
===>Configuration Descriptor<===
bLength: 0x09
bDescriptorType: 0x02
wTotalLength: 0x0043 -> Validated
bNumInterfaces: 0x02
bConfigurationValue: 0x01
iConfiguration: 0x00
bmAttributes: 0xC0 -> Self Powered
MaxPower: 0x32 = 100 mA
===>Interface Descriptor<===
bLength: 0x09
bDescriptorType: 0x04
bInterfaceNumber: 0x00
bAlternateSetting: 0x00
bNumEndpoints: 0x01
bInterfaceClass: 0x02 -> This is Communications (CDC Control) USB Device Interface Class
bInterfaceSubClass: 0x02
bInterfaceProtocol: 0x01
iInterface: 0x00
-> This is a Communications (CDC Control) USB Device Interface Class
===>Descriptor Hex Dump<===
bLength: 0x05
bDescriptorType: 0x24
05 24 00 10 01
-> This is a Communications (CDC Control) USB Device Interface Class
===>Descriptor Hex Dump<===
bLength: 0x05
bDescriptorType: 0x24
05 24 01 00 01
-> This is a Communications (CDC Control) USB Device Interface Class
===>Descriptor Hex Dump<===
bLength: 0x04
bDescriptorType: 0x24
04 24 02 02
-> This is a Communications (CDC Control) USB Device Interface Class
===>Descriptor Hex Dump<===
bLength: 0x05
bDescriptorType: 0x24
05 24 06 00 01
===>Endpoint Descriptor<===
bLength: 0x07
bDescriptorType: 0x05
bEndpointAddress: 0x82 -> Direction: IN - EndpointID: 2
bmAttributes: 0x03 -> Interrupt Transfer Type
wMaxPacketSize: 0x0008 = 0x08 bytes
bInterval: 0x10
===>Interface Descriptor<===
bLength: 0x09
bDescriptorType: 0x04
bInterfaceNumber: 0x01
bAlternateSetting: 0x00
bNumEndpoints: 0x02
bInterfaceClass: 0x0A -> This is a CDC Data USB Device Interface Class
bInterfaceSubClass: 0x00
bInterfaceProtocol: 0x00
iInterface: 0x00
===>Endpoint Descriptor<===
bLength: 0x07
bDescriptorType: 0x05
bEndpointAddress: 0x01 -> Direction: OUT - EndpointID: 1
bmAttributes: 0x02 -> Bulk Transfer Type
wMaxPacketSize: 0x0040 = 0x40 bytes
bInterval: 0x00
===>Endpoint Descriptor<===
bLength: 0x07
bDescriptorType: 0x05
bEndpointAddress: 0x81 -> Direction: IN - EndpointID: 1
bmAttributes: 0x02 -> Bulk Transfer Type
wMaxPacketSize: 0x0040 = 0x40 bytes
bInterval: 0x00
Upvotes: 2
Views: 18097
Answers (2)
Reputation: 178
I had the same problem, i could read the device and see which com port but i could not open one. (for a CDC)
then i encountered following post with the last answer having the solution for my problem: https://community.st.com/s/question/0D50X00009XkgIYSAZ/unable-to-configure-serial-port-error-for-usb-cdc
there it mentions you need to add several lines if you want to communicate RS232 through a VCP.
I added following in usbd_cdc_if.c file:
/*******************************************************************************/
/* Line Coding Structure */
/*-----------------------------------------------------------------------------*/
/* Offset | Field | Size | Value | Description */
/* 0 | dwDTERate | 4 | Number |Data terminal rate, in bits per second*/
/* 4 | bCharFormat | 1 | Number | Stop bits */
/* 0 - 1 Stop bit */
/* 1 - 1.5 Stop bits */
/* 2 - 2 Stop bits */
/* 5 | bParityType | 1 | Number | Parity */
/* 0 - None */
/* 1 - Odd */
/* 2 - Even */
/* 3 - Mark */
/* 4 - Space */
/* 6 | bDataBits | 1 | Number Data bits (5, 6, 7, 8 or 16). */
/*******************************************************************************/
static uint8_t lineCoding[7] // 115200bps, 1stop, no parity, 8bit
= { 0x00, 0xC2, 0x01, 0x00, 0x00, 0x00, 0x08 };
and adjusted CDC_Control_FS function:
static int8_t CDC_Control_FS(uint8_t cmd, uint8_t* pbuf, uint16_t length)
{
/* USER CODE BEGIN 5 */
switch(cmd)
{
...
case CDC_SET_LINE_CODING:
memcpy(lineCoding, pbuf, sizeof(lineCoding));
break;
case CDC_GET_LINE_CODING:
memcpy(pbuf, lineCoding, sizeof(lineCoding));
break;
...
}
I hope this is still useful for you.
Upvotes: 13
Reputation: 103
Firmware FW1.4.0 for STM32H7 works incorrect. I must used FW1.3.2 and CubeMX 5.2.1.
But if I init FMC bus, virtual COM port works incorrect again, if I comment initialization, it works correct again
MX_USB_DEVICE_Init();
// MX_FMC_Init();
Interesting, what C functions: "fopen("COM6", "r+"), fwrite, fgetc, fclose" - work in Windows 10 with FW1.4.0 without port configuration. Error of FW1.4.0 is in writing port parameters (baud, bits or others) and virtual COM port Windows driver arises exception if cannot write parameters into USB device
Upvotes: 0
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