the difference of software between UJA1169TK and UJA1169TK/F

[liuxing_hu]

we already have a SOP product using UJA1169TK which don't support CAN FD, it works well, but now this product have to send message to another product which support CAN FD, our product will report error frame which influence message rx/tx.

so to avoid error frame, we have a solution, to directly replace UJA1169TK with UJA1169TK/F hardware, so my question is what shall be changed by sw? is there anything about sw configuration to change by sw ?

[PetrS]

Hi,

UJA1169 supports CAN FD active communication up to 2 Mbit/s, but if your MCU does not support CAN FD then for receiving CAN FD message the MCU generates frame error.
The /F variant adds CAN partial networking with a selective wake-up function incorporating CAN FD-passive. CAN FD-passive is a feature that allows CAN FD bus traffic to be ignored in Sleep/Standby mode.

So question is, if this is what you are looking for. You should put UJA1169/F into Sleep/Standby mode with CAN PN properly configured. Incoming CAN FD frames are ignored. Defined wake up frame wakes UJA1169/F and MCU can sent CAN2.0 message, other nodes should not send CAN FD message until this UJA1169/F will be in sleep again. 

BR, Petr

[liuxing_hu]

Hello PetrS

Thanks for your response!

1. our MCU is SAMC21J17A, it supports CAN FD, you can refer to the follow picture

2.UJA1169ATK don't support to receive CAN FD from other nodes ,you can see this picture, so I think error frame is reported by UJA1169ATK, not MCU

3.only my request is that my product with UJA1169ATK connects with other nodes sending CAN FD frames, error frames can be avoided. is there any solution to solve?

4.Can we replace UJA1169ATK hardware with UJA1169ATK/F directly in PCBA, and enable CFDC, Can the communication function work well? 

[PetrS]

Hi,

ad 2) UJA1169ATK supports CAN FD as well. So there should not be issue with CAN FD communication between your MCU and other nodes if using UJA1169ATK in normal active mode.

UJA1169 does not send/generate any CAN error frames, this is done by CAN controller. 

ad 3) I do not expect issues with CAN FD in UJA1169ATK, see above

ad 4) you can, but CAN FD passive mode is used just in low power modes. It allows normal CAN controllers that do not support CAN FD to remain in partial networking Sleep/Standby mode during CAN FD communication without generating bus errors.

BR, Petr

[liuxing_hu]

Hello PetrS

1.what's the different between CAN FD active communication and CAN FD passive ?
2.UJA1169ATK can only support CAN FD active communication, not CAN FD passive, only /F variants support FD-passive features and partial networking protocol.
The /F variants can be configured to recognize CAN FD frames as valid CAN frames.
When CFDC = 1, the error counter is decremented every time the control field of a CAN
FD frame is received.

CAN FD frames are interpreted as frames with errors by the partial networking module
when CFDC = 0. So the error counter is incremented when a CAN FD frame is received

you can see there is a situation that can generate error frame when CFDC = 0, could it be the reason? can we solve it by setting CFDC = 1?

[PetrS · Accepted solution]

Hi,

1) CAN FD active: SBC in Normal mode (or Forced Normal), CAN transceiver in Active mode. Normal CAN communication is possible, so transmitting and receiving CAN FD messages as well (up to 5Mbit/s).

CAN FD Passive: SBC in Standby or Sleep mode, CAN transceiver Offline. The transceiver is unable to transmit or receive data. If remote CAN wake-up is enabled, the receiver monitors bus activity for a wake-up request. Can be standard wake-up pattern or a selective wake-up frame (partial networking). The /F variants can be configured to recognize CAN FD frames as valid CAN frames if CFDC=1 (decrements internal error counter also for CAN FD message). The /F devices still remains in low-power mode (CAN FD-passive) with partial networking enabled. CAN FD frames are never recognized as valid wake-up frames.
If CFDC=0, CAN FD frames are interpreted as frames with errors by the partial networking module, internal error counter increments, if exceeds threshold, device wakes up.

It is just internal error counter, determines wakeup threshold. Device does not generate any error frame on the bus.

So if you need to have SBC in low power mode and ignore CAN FD frames (do not wakeup on CAN FD frame) then /F variant is needed.

BR, Petr