S32K148 FLEXCAN cannot get IDHIT value in RXFIR or in RX FIFO

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S32K148 FLEXCAN cannot get IDHIT value in RXFIR or in RX FIFO

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jlu
Contributor I

The configuration is using RX FIFO and interrupt. I can read a message from the CAN BUS, and I can output a message. I setup 8 ID filters for RX FIFO. The filters work fine - there is no interrupt when there is no ID match, and there IS a RXFIFO interrupt when there is one match. However, regardless where I put the correct ID filter, the RXFIR always shows IDHIT as 0. Should not it show the index of the matching filter?

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PetrS
NXP TechSupport
NXP TechSupport

Hi,

yes the RXFIR includes IDHIT and it is valid while the IFLAG1[BUF5I] flag is asserted. The RXFIR register must
be read only before clearing the flag. Also IDHIT can be read from C/S word, as shown in the Rx FIFO Structure description.

If have issues still please share filter table, mask registers and the way you read RXFIFO and RXFIR.

BR, Petr 

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