µTasker Forum
µTasker Forum => NXPTM M522XX, KINETIS and i.MX RT => Topic started by: izzz on March 31, 2010, 03:12:42 PM
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Hello,
I'm working with uTasker and MCF52235 microcontroller and I have problems when I try to SoftReset FlexCAN.
When I try to send/receive CAN messages, CAN_OTHER_INTERRUPT in uTasker is awaken. When that happens I try to reset FlexCAN, but often an unhandled exception (0x40602000) occurs when doing so the program enter in the while(1) defined inside de handler undef_int(void) in M5223X.c and stands there forever.
All the CAN interrupts are initialized (_CAN_buf_Interrupt0 to 15, _CAN_bus_off_Interrupt and _CAN_error_Interrupt) so every one has a handler.
I'm having problems when I use long cables between two boards communicated by CAN bus. I have the termination resistors at the end and at the begin of the cables.
This is my SoftReset FlexCAN code:
void fnResetCAN(void){
unsigned int counter;
if (CAN_ERRSTAT & (CAN_BUS_IDLE|CAN_ERROR_PASSIVE)){
unsigned int imask = CAN_IMASK;
unsigned int canmcr = CANMCR;
CANMCR |= CAN_SOFTRST;
for (counter=0; counter<500, (CANMCR & CAN_SOFTRST);counter++){}
CAN_IMASK = imask;
CANMCR |= canmcr;
CANMCR &= ~(CAN_FRZ | CAN_HALT);
}
}
Hope you can help me,
Ivan
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Hi Ivan
I would first try solving the problem that you are having when performing a soft reset.
Also an exception error will result in the undefined interrupt being called (this is more likely than an undefined interrupt from a peripheral source).
Follow the instructions here to try to identify the code that is causing this:
http://www.utasker.com/forum/index.php?topic=123.msg468#msg468
Generally only the CAN_ACK_ERROR (either CAN_TX_REMOTE_ERROR or CAN_TX_ERROR) are expected during normal operation when a destination doesn't respond. Other error sources are (BIT1ERROR | BIT0ERROR | CAN_CRC_ERR | CAN_FRM_ERR | CAN_STF_ERR), which generate the warning error event that is occurring. You can identify the actual error in more detail if you look at the variable ulError (copied from CAN_ERRSTAT) when the event is generated (in the _CAN_error_Interrupt() interrupt handler) - this may help identify the source of un-reliability.
Regards
Mark
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I tried what you said and here's the results:
1- The Stack Pointer is 0x20007F6C
(http://img29.imageshack.us/img29/9751/step1k.gif) (http://img29.imageshack.us/i/step1k.gif/)
2- I opened a View Memory window and found:
+ Exception 0x40602000:
Format = 0x4
Status Reg = 0x2000
Vector = 0x18 (Reserved)
Fault Status = 0x0 (Reserved)
+ Program Counter: 0x00020B9C
(http://img714.imageshack.us/img714/4439/step2.gif) (http://img714.imageshack.us/i/step2.gif/)
I don't know where's the problem, the vector and fault status are reserved.
3- Using the call stack I can't not found nothing interesting except that the exception is fired when accessing fnCAN
(http://img188.imageshack.us/img188/6272/step3m.gif) (http://img188.imageshack.us/i/step3m.gif/)
4- It seems that's a problem setting the SOFT_RESET bit, isn't it?
(http://img535.imageshack.us/img535/6554/step4.gif) (http://img535.imageshack.us/i/step4.gif/)
I replaced the for loop for a while loop but is always the same, it seems that the exception is fired always before entering in the wait-for-softreset-done loop
Any idea?
Regards,
Ivan
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Hi Ivan
The vector 0x18 is 24, which is a spurious interrupt.
This suggests that the setting of the CAN_SOFTRST is causing a spurious interrupt to be generated. I don't know why this is at the moment but check first than no CAN interrupt priorities (level/priority) collide with any other interrupts in the system (see app_hw_m5223x.h). Such a collision is one possible cause of spurious interrupts.
I will do some thinking on how such an event can be possible - at the moment such an occurrence is new to me...
Regards
Mark
PS: Try disabling interrupt before executing the soft reset and enabling them again afterward. Maybe there is a difference which may help explain something.
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I checked the interrupt priorities. There was a non-CAN interrupt (RXFRAME_INTERRUPT_PRIORITY) with same level/priority as CAN_interrupt_15. I changed it to level 4, priority 2 (because that lvl/pri was free) but still gets stuck.
I tried disabling and enabling the interrupts before and after softreset and seems that works. That can explain why and spurious interrupt is fired?
Regards,
Ivan