USB  as multiple COM ports?

The question was abourt USB-UARTs (CDC ports), not about physical UARTS.

I would guess that USB would support having multiple virtual COM ports over a single USB connection. For example the FT2232 supports this IIRC. But I would also guess that the default windows driver cannot handle this...

Also, the USBUART component cannot handle this AFAIK, you would need to roll your own USB device driver on the PSoC side...

What is your use case here? Is there a reason not to handle multiple transfers of a single COM port? (I think the useable bandwidth would also be reduced in this scenario).

Hi Goose,

I am attempting to do the same. Could you advise me on how I can do this?

Many thanks,

G

hello

I have created a composite device with two COM ports.

One COM port is operating correctly but the other COM port is not working properly...

Where should I fix it?

It seems that there is an API function USBUART_GetComPort(void) to select one of two COM ports.  Following snapshot comes from the USBUART component datasheet.

Actually, I didn't use this API function.  Can you try this API function?

Regards,

Noriaki

thank you for your reply.

I described SetComPort for each EP interrupt in USBUART_1_episr.c

For the time being, the program is working as intended.

Is this the correct way?

You don't need to modify the episr file.  Just call USBUART_SetComPort() before calling port associated APIs.  I have modified the project attached to this discussion as follows.

   for(;;)
   {
        // the number of bytes        
        USBUART_SetComPort(USBUART_COM_PORT1);
        Count = USBUART_GetCount();
        
        if(Count != 0){
            //Get data
            USBUART_SetComPort(USBUART_COM_PORT1);
            USBUART_GetAll(Buffer);


            if(Buffer[0] == '?'){
                // Send data
                USBUART_SetComPort(USBUART_COM_PORT2);
                USBUART_PutData(Hello, Count2);
                //wait tx
                USBUART_SetComPort(USBUART_COM_PORT2);
                while(!USBUART_CDCIsReady()){}
            }else{
                // Echo data
                USBUART_SetComPort(USBUART_COM_PORT1);
                USBUART_PutData(Buffer, Count);
                //wait tx
                USBUART_SetComPort(USBUART_COM_PORT1);
                while(!USBUART_CDCIsReady()){}
            }
        }
    }

And the execution result as follows.

At the end of for-loop you called USBUART_DataIsReady() API function to wait for TX completed.  But the API is incorrect.  USBUART_CDCIsReady is used to wait for the TX completion.

Attached project is modified for the CY8CKIT-059 without using the external crystal oscillator.

Regards,

Noriaki

Thank you for your kindness.

We will provide a project for SetComPort in USBUART_1_episr.c for reference only.

And the execution result as follows.

The attached project file was created with CY8C5868AXI-LP035.

Please let me add a comment.

It is recommended to use a MACRO CALLBACK feature to add your own code to the ISR procedure.  You can declare a CALLBACK in the "cyapicallbacks.h" header file like as follows to be invoked from the ISR .

#ifndef CYAPICALLBACKS_H
#define CYAPICALLBACKS_H
    

    /*Define your macro callbacks here */
    /*For more information, refer to the Writing Code topic in the PSoC Creator Help.*/
    #define USBUART_1_EP_1_ISR_ENTRY_CALLBACK
    extern void USBUART_1_EP_1_ISR_EntryCallback(void);
    
    #define USBUART_1_EP_2_ISR_ENTRY_CALLBACK
    extern void USBUART_1_EP_2_ISR_EntryCallback(void);

    
#endif /* CYAPICALLBACKS_H */   

The callback function can be described in any C files like main.c

void USBUART_1_EP_1_ISR_EntryCallback(void) {
    USBUART_1_SetComPort(0);
}

void USBUART_1_EP_2_ISR_EntryCallback(void) {
    USBUART_1_SetComPort(0);
}

This feature was implemented in PSoC Creator 3.3  You don't need to modify the "Generated_Source" files anymore when using the CALLBACK feature.

Regards,

Noriaki