topic imx6: FlexCAN error count not increasing proper at 500Kbps/ 1Mbps in i.MX Processors

imx6: FlexCAN error count not increasing proper at 500Kbps/ 1Mbps

shashikanthirem — Tue, 01 Jan 2019 07:56:17 GMT

Hi All,

i am working on flexcan driver related application on imx6q freescale processor

i have a CAN network with one node A sending continuous can frame, bus speed at 125 kbps towards node B receiving, then everything is normal well and fine.

i am generating Error Frame using Canking (CAN analyser) software from PC with 500 kbps or any other baud rate apart from working bus speed 125kbps

i am checking with two processor one is with imx28(2.6.35.XX kernel) and other with imx6q (3.10.XX kernel)

for 1 min, with imx 28 , tx passive error count nearly 1000 where as with imx6q the tx passive error count(FLEXCANX__ECR -- error counter register) nearly 100 where as in CAN analyser Error frames are near to 10000 for 1 min.

1. Could you make me understand why the passive error count are different in processor and the CAN analyser are different ?

2. looks like passive error count are not properly catched by the flexcan error count register at 500Kbps/ 1Mbps, but neatly works < 500Kbps. could anyone suggest why this happening..?

Re: imx6: FlexCAN error count not increasing proper at 500Kbps/ 1Mbps

art — Thu, 24 Jan 2019 09:09:23 GMT

Please refer to the Section 26.8.7 "Error Counter Register (FLEXCANx_ECR)" of the i.MX6Dual/Quad Reference Manual document, available on the processor's Documentation web page:

https://www.nxp.com/products/processors-and-microcontrollers/arm-based-processors-and-mcus/i.mx-applications-processors/i.mx-6-processors/i.mx-6quad-processors-high-performance-3d-graphics-hd-video-arm-cortex-a9-core:i.MX6Q?tab=Documentation_Tab

In particular, it says the following.

"If the Rx_Err_Counter increases to a value greater than 127, it is not incremented further, even if more errors are detected while being a receiver".

So, the RX_ERR_COUNTER cannot count more than 128 consecutive receive errors.

Have a great day,
Artur

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