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Buffering CAN RX Messages - Missing Messages When TX Flow Control

Question asked by Jason Blackston on Aug 25, 2013
Latest reply on Aug 26, 2013 by Jason Blackston

My design has me using 3 RX mailboxes with MQX 4.0. I have the design almost laid out like the FlexCAN demo where I have a task setup for each RX mailbox and an interrupt to set the event for the task to know when it is ready to read data. I also have a CAN TX task that I pass messages off to when I need to transmit a message. I can receive all data on a CAN network with no issues when on vehicles.

 

The issue I run into is when I'm trying to handle multi-frame responses. When I receive the first frame 0x10 I send the flow control message 0x30 0x00 0x00, the issue though is the vehicle will then transmit the rest of the frames but I only receive the send frame 0x22, I'm missing the first frme after the flow control message 0x21. Why? I even place break points in the RX mailbox to break upon recieving an 0x21 or 0x22 message and it never breaks on a 0x21 message. It's like even though I have 3 RX mailboxes running I'm missing data right after I transmit the flow message.

 

Any ideas as to solve this issue of missing messages?

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