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Hello,
i´m working on a K-Line interface using a STM32F105. The middleware lib is successfully installed and the virtual com port is running good with the CDC ACM feature.
Now there is a special problem. The KWP2000 protocol is using a special RS232 feature called send line break condition. There is a SEND_BREAK request (23h) send from Windows via the usbser.sys driver to the middleware library. So the cortex as to apply a positiv voltage on the rs-232 tx-line.
I could´t find the point or the function which is called or is it not implemented in the usb device class?
Hi Wolf,
the only thing that CDC offers regarding break signalling is SEND_BREAK command 23h, which is specified in details in PSTN120.pdf from USB.org file.
If you are able to see USB traffic then when you do your mentioned "IOCTL_SERIAL_SET_BREAK_ON" you should be able to see control endpoint 0 request SEND_BREAK.
That request will be passed to USBD_CDC_ACM_CoreSendBreak function which if you implement it will do whatever you implement.