[H730] FDCAN Transmitting messages leads bus to off state

[AAlex.20]

Bus speed - 100kbit/s in CAN 2.0 mode

FDCAN clk - 48Mhz

Prescaler - 24 (bit length 20tq)

TQ1 - 15 (sample point 80%)

TQ2 - 4

SJW - 4

Receiving CAN messages without any problems, bus seems to be ok, even if FDCAN in normal mode(error counters are 0). But if I try to send something, bus nodes put Error state after the transmitted frame. Tried to adjust the sample point from 50% to 90% - the same. Tried to use HSE as clock source (12Mhz) instead of PLL1 - no differences. Tranceivers are TJA1041, that work perfectly on Cortex - M4 MCU with the same bus. I noticed 1 us difference between recessive bit of the transmitted frame and any of received frames (~9.6us against ~10.5us), but slight speed adjustment leads to receive errors.

[SofLit]

Hello,

I think you wanted to say 100kbit/s

Try to decrease the prescaler as much as possible and increase TQ1 and TQ2 and use HSE+PLL as source clock to match 100kb/s.

I don't know what is your system clock value but please try to use higher frequencies.

[AAlex.20]

Sure, I ment 100kb/s.

HSE - 12Mhz

Tried different configs

HSE+PLL1 - 96MHz

BRP - 1

TSEG1 - 149

TSEG2 - 50

tq per bit - 200

HSE+PLL1 - 48MHz

BRP - 1

TSEG1 - 74

TSEG2 - 25

tq per bit - 100

On these two FDCAN raise error passive flag and goes to idle, no data received.

HSE+PLL1 - 48MHz

BRP - 6

TSEG1 - 59

TSEG2 - 20

tq per bit - 80

HSE+PLL1 - 48MHz

BRP - 12

TSEG1 - 29

TSEG2 - 10

tq per bit - 40

HSE+PLL1 - 48MHz

BRP - 24

TSEG1 - 14

TSEG2 - 5

tq per bit - 20

HSE+PLL1 - 12MHz

BRP - 3

TSEG1 - 29

TSEG2 - 10

tq per bit - 40

On these configs behavior is the same: receive - just fine, transmit - fail as I mentioned above.

I found that FDCAN1 and FDCAN2 behavior on same configs is different. Some of FDCAN1 packets reaches other nodes, I see some discontinous reaction of executive mechanisms.All packets transmitted from FDCAN2 are discarded with error.

[SofLit]

Check your Tx path: GPIO pin, transceiver, etc..

+ Check the power supply of your transceiver + its stability