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Is there a way to check for an empty transmit buffer with raw socketcan?

EDIT: Or is there a way to make socketcan blocking until the current frame is sent which would serve the same purpose ...

(motivation: I'm writing a mcu flash tool over can. The bootloader spec calls for a waiting time after a certain amount of data sent in order for it to do the writing to flash. Depending on the bus load the sending of the data could be faster or slower.)

Scheintod
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1 Answers1

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SocketCAN sockets only block until the frame is put into the socket buffer (although see section 3.4 in https://rtime.felk.cvut.cz/can/socketcan-qdisc-final.pdf for some subtle complications).

If you want to discover if a frame was successfully sent, enable the CAN_RAW_RECV_OWN_MSGS socket option and wait until you receive the sent frame with the MSG_CONFIRM flag set. See this answer for more details.

Jos Seldenthuis
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  • According to https://support.crosscontrol.com/kb/accessing-can-bus-qt-socketcan, "If the TX buffer is full, sending a message will not block but will return an error code". Just additional clarification. – avra Jun 11 '21 at 10:09