For the sockets that are failing:
TMSR is set to 27kBytes per socket
RMSR is set to 2kBytes per socket; I think this is what you are seeing in the capture file where Win=2046, but these sockets don’t receive data, they just send data
Yes, I check TX_FSR before sending. But this only verifies that there is buffer space in the W5300 TX Buffer (27kBytes to start). It does not indicate the peer Window size. I think there is no way for me to know the peer window size. The W5300 uses it internally but doesn’t give me access to it.
Your statement that “the next 1460 data packet can’t be sent without ack packet of 1st data packet” is not consistent with the answer in this forum topic:
After the first transmission, I wait for the SENDOK flag to be set, then I clear it, then I check TX_FSR to verify that there is space in the TX buffer, and if there is space, then I send another packet. According to that post, when the ACK is received, the TX_FSR increases by the amount of data that was acknowledged by the peer, but I should not have to wait for an ACK after every packet. If I did that, I would wait for TX_FSR to show 27kBytes before I send each packet, and my data rate will go down. I’ve tried that.
