Other Parts Discussed in Thread: TCAN1145-Q1
Tool/software:
We are trying to use the sleep mode feature of the TCAN1043A-Q1 CAN chip (specifically with the INH pin on this chip). We spend most of our time in "normal mode" with the EN and nSTB pin high. The external ignition input (KL15) is connected to the CAN chip's WAKE pin. When we detect a falling edge on the ignition pin (wake pin), we set the nSTB pin to low which transitions us into the "Go-to-sleep" mode. After 50us we transfer to sleep mode. As long as the CAN bus is quiet this works perfectly.
If there is any traffic on the CAN bus we immediately transfer to standby mode because the nSTB pin is low and the EN pin is left high. This then requires the SWE timer to expire before moving back into sleep mode. We cannot wait 5 minutes to transfer so to combat this, I have implemented a nSTB pin toggle every 1sec to transfer through from "standby" to "Go-To-Sleep mode". This does seem to move to sleep mode within 1 sec of a quiet bus.
It seems likely that there will be traffic on a CAN bus when we are trying to go to sleep, is it expected that we just stay in standby until nothing has been on the bus for 5 minutes... this seems odd. The 1 sec nSTB toggle helps transfer to "sleep" mode quicker than 5 minutes but still requires the bus to be completely quiet.
What we would like to do is transition to "sleep mode" when a specific condition occurs. There is a chance there will still be traffic on the CAN bus when this occurs, we would like to not wake up for a period of time after we transfer to "sleep mode". If ignoring CAN wake for a period of time is not possible is it possible to disable CAN wake all together and just wake from external wake input.
Our intended design is to follow the RED underlines below, but with CAN traffic on the bus we follow the yellow, and then with the toggle I implemented the chip follows the blue underline.
We would like to know your thoughts on our design and if we can turn off without immediately waking from traffic on the CAN bus.
