SPRUIM2H May 2020 – October 2023 AM2431 , AM2432 , AM2434 , AM6411 , AM6412 , AM6421 , AM6422 , AM6441 , AM6442
The measurement reference for the IPG of 96-bit times is changed depending on frame traffic conditions. If a frame is successfully transmitted without collision, and MCRS is de-asserted within approximately 48-bit times of MTXEN being de-asserted, then 96-bit times is measured from MTXEN. If the frame suffered a collision, or if MCRS is not de-asserted until more than approximately 48-bit times after MTXEN is de-asserted, then 96-bit times (approximately, but not less) is measured from MCRS.
The Ethernet port transmit inter-packet gap (IPG) may be shortened by eight bit times when short gap is enabled and triggered. Setting the [10] TX_SHORT_GAP_ENABLE bit in the CPSW_PN_MAC_CONTROL_REG register enables the gap to be shortened when triggered. The condition is triggered when the ports associated transmit packet FIFO has a user defined number of FIFO blocks used. The associated transmit FIFO blocks used value determines if the gap is shortened, and so on. The CPSW_GAP_THRESH_REG register value determines the short gap threshold. If the FIFO blocks used is greater than or equal to the GAP_THRESH value then short gap is triggered.