ex_usb_serial

georpo · Joined: 18 Nov 2008 Posts: 278 Location: Athens, Greece.

Hello forum!

I used the usb to serial example with success but here is a question.
How can I use handshaking to make the pc wait between transmisions?

There is no CTS here like RS232...

Thanks

FvM · Joined: 27 Aug 2008 Posts: 2337 Location: Germany

CTS isn't needed. The PC stopps sending data, if the TX endpoint buffer isn't emptied at the USB device side.

georpo · Joined: 18 Nov 2008 Posts: 278 Location: Athens, Greece.

This is great news!
So, If I do not "usb_cdc_getc()" then the pc waits till I do. Right?

FvM · Joined: 27 Aug 2008 Posts: 2337 Location: Germany

Yes. When the USB device and PC commdriver buffers are full, WriteFile() returns with zero bytes written. It's important not to ignore the WriteFile() result.

georpo · Joined: 18 Nov 2008 Posts: 278 Location: Athens, Greece.

I am not sure what WriteFile() is. I am using visual basic to send data to the pic through the visual cdc port.
The command is "comport.output=data" I do not think that this returns anything. Any help appreciated!

Something else, how do I know that I am running at full speed? The example is supposed to use internal pullup resistors but I cannot find this anywhere in the code. I tried to send a 100KB file and it needs 100 seconds to finish!