TCAN1043A-Q1: How to find the rising edge of INH pin

Hi TY,

1. 

TY M said:

so INH pin always equal to high and SBC can not detect rising edge which will lead SBC to the standy state(SBC state).

Could you clarify what does "SBC can not detect rising edge" mean here?  From which mode going to standby mode? 

2. 

TY M said:

Is this the only way to detect rising edge of INH pin?

So the purpose is to detecting rising edge of INH? Because INH will only be low in sleep mode (or powered off), a rising edge of INH can only happen after wake up or power on.

3. Regarding the initialization process, do you mean the initial power up or cold start? There is a delay of INH,

but tuv is different. It is the timer when under voltage condition happen at VIO or VCC, after tuv if those supplies not recovered, the device enters sleep mode.

Regards,

Sean

Hi  Sean：

"SBC can not detect rising edge" mean：

When transceiver enter the standby mode from Go-to-Sleep mode ,then the SBC change the mode from Normal mode to Standby mode .

If met this case, the INH pin will not be pulled down, unless SWE timer expires?

Hi Sean:

But if wake-up message is always sending when met under voltage condition, which  status of the Transceiver at this time?

back to sleep mode from standby mode after tuv ?or still in the standby mode?

HI TY,

The WUP (wake-up message) won't stop the device from entering sleep mode if under voltage condition > tuv. 

TY M said:

back to sleep mode from standby mode after tuv ?

Yes, It will go back to sleep mode.

Regards,

Sean

hi Sean:

This picture shows the process of  Pin INH ,Pin EN ,Pin STB ,Pin  Transceiver power supply(5v),current from shutdown to wake up . The question is when Pin 5v(Transceiver power supply) is pulled down,and Pin INH  was pulled down and immediately pulled up  because of wake up message (The point at which it was pulled down and pulled up may not have been picked up in the picture because of the sampling frequency),and Pin INH always =high.

Why Pin INH is always high? In my understanding, 5V supply had changed to 0v, and the transceiver will under voltage condition ,the transceiver has to change the mode to sleep mode after tuv. But in this test ,the Pin INH is pulled down until no wake up message.Why Pin INH not be pulled down during the supply power = 0v?

Hi TY,

Please correct me if I misunderstood, you said INH is always high, yes it seems stay in high because you said the points at which it was pulled down and pulled up may not have been picked up in the picture because of the sampling frequency, so jf there is no wake up pattern on the bus, will INH go to low?

Regards,

Sean

Hi Sean:

    The line of NM_DUMMY is wake up message, and the period of this message is 5 ms, it lasted for 10 seconds in my picture.

During this 10 seconds, Pin INH is always high. SBC can not detected the rising edge of Pin INH ,so ECU can not wake up again.

Hi TY,

TY M said:

The question is when Pin 5v(Transceiver power supply) is pulled down,and Pin INH  was pulled down and immediately pulled up  because of wake up message (The point at which it was pulled down and pulled up may not have been picked up in the picture because of the sampling frequency)

This is true, the device will first enter sleep mode, pull INH low, and immediately enter standby mode due to WUP. Can you adjust the sampling frequency to detect this rising edge? Or can you try to send the WUP after the falling edge of INH is detected?

Regards,

Sean

Hi Sean:

I find that Pin INH always high in my test(Grab with an oscilloscope) before under voltage and after under voltage.During this process, CANOE kept sending wake-up message with busload=90%.After 3-5min, Pin INH was pulled down and then the ECU woke up.

But when I look at the screenshot below, I think transceiver will enter to sleep mode after tuv, not tinactive?

Another question is when Pin INH from high to low after tincative, and CANOE kept sending wake-up message during these times,so PIN INH will be quickly pulled up, how long the low level of Pin INH  is held during this period?

...

Hi TY,

I didn't see the screenshot, but that 3-5 min is the SWE timer expiring time when the device stuck in standby mode. As CANoe is keep sending wake-up pattern the device will be just held at standby mode. tuv timer will be disabled in this case, until VCC and VIO rise above under voltage threshold.

The INH hold time will be equal to the mode transition time:

Regards,

Sean

Hi Sean:

As CANOE is keep sending wake-up pattern ，the Pin INH keeps high level.(as shown above)

In my understanding, tuv will be abled  when transceiver in the other mode(except sleep mode) before under voltage. But in this case, Pin INH was pulled down after 3-5min.

Will Tinactive be enabled before under voltage?

Under what conditions would this result occur?

Hi TY,

TY M said:

I find that Pin INH always high in my test(Grab with an oscilloscope) before under voltage and after under voltage.During this process, CANOE kept sending wake-up message with busload=90%.After 3-5min, Pin INH was pulled down and then the ECU woke up.

After INH was pulled down in the case of waiting 3-5mins, was CANOE still keeping sending the wake-up patterns? A wake event will transition the device to standby mode, even if the SWE timer is the reason for entering sleep mode. So you didn't see INH being pulled high again?

If there is continuous communication on the CAN bus, it is possible that the INH will remain high through this sleep mode - standby mode pattern. Because the INH signal is an open-source output, it takes time for the signal to decay. Depending on the frequency of communication on CAN bus, it's possible that the INH will never fall below a certain voltage. 

Regards,

Sean