some problems about MC33908 wake up using IO

[彭冬冬]

hi ,now im using the MC33908 SBC chip ,the problem i got is  how to use the IO_0 to wake up the SBC, i use the following code make the SBC chip in a LPOFF state sucessfully ,but when i intend to wake up the SBC using IO_0 wake up , i failed , these is a very strange phenomenon, i can wake up the SBC for a very short time using rising edge of IO_0, but it can not last for good, i dont know why , anybody who is familiar with this chip  can help me out? thanks a lot in advance.

void PwSBC_SleepMode(void){
Status_16B_tag status;
uint16_t cmd;

//Put Can in sleep mode with no wakeup
// cmd = 0xB000;
// cmd = PwSBC_ComputeParity(cmd);
// status = PwSBC_SetMainReg(cmd); //Can enters sleep mode

cmd = 0xAA20;// LPOFF command according to datasheet
cmd = PwSBC_ComputeSecurityBits(cmd);
cmd = PwSBC_ComputeParity(cmd);
status = PwSBC_SetMainReg(cmd);// send command twice 
status = PwSBC_SetMainReg(cmd);
}

[guoweisun]

Hi

please double check your wake up timing with attached page27/28. If necessary please provide the part schematic and test waveform of this wake up function.

[彭冬冬]

G.w. Sun ,thanks for your reply sincerely.

1、 IGN signal is connected  to 12V battery, IO_0 is configured to be awaken by rising edge

2、 the part schematic is just as  picture shows

3、i read the document you uploaded  carefully, it says before you enter LPOFF, need to make the SBC in a normal state, then a IO rising edge coming, the SBC back to power on again for good, is this how the wake-up function works?

datasheet not tell us what kind of state the SBC exactly is? when wake up happen ,does the SBC transfer from LPOFF state to normal state,or what else  i should do further? and i need to emphasize that  the SBC can be awaken but in a few second ,not totally can be wake up. the power indication light just flash one time, not light on all the time .

4、first , i initalize SBC Module, put it in normal state by configuration the register(INT), then put PwSBC_SleepMode in the end of the initalization program, so when i turn on power for circuit board , the SBC should be in a LPOFF state, then attach the IGN signal to 12V power supply,  to simulate a rising edge of IO_0,  but the power indication flash one time ,then all regulators power off ,just like it enter the LPOFF again, is  there any logcial mistake ?

[guoweisun]

HI

I do a test in EVB about the wake up function which you can refer to it.

Step below list:

1: power on EVB

2: Configure interrupt registers which including the wake up function ,at last configure INIT INT register enter normal mode.

3: Send SPI commend enter into sleep mode.

4: do a corresponding wake up operation which you have set in your setp2.

Thanks!

[彭冬冬]

• so，i figure some problem out for you,  is your test successful? can you tell me  the result in details? and send some part of your code as a reference related to SBC  to me ? Thanks!

[guoweisun]

I test successfully wake up function in EVB and based on GUI setting the SPI commands.

I attached related user manual of EVB.

[彭冬冬]

thanks for your answer!,can you send me a paper of user manual of EVB,  i dont have that paper?  i think maybe some problem about SPI  command.

[guoweisun]

Please see my last reply attached file!