__WFI() will not sleep even with all interrupts disabled and pending cleared - LPC18XX Series
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Background: I am trying to make my embedded application go to sleep when there is no CAN activity with the __WFI() and then wake up whenever a CAN interrupt is received. Before enterring sleep mode, I disable all interrupts and clear their pending states in the NVIC registers.
To start, right now I'm just trying to make sure that I can sleep forever when I have all interrupts disabled.
for(int i = 0; i < IRQ_MAX; i++)
{
IRQ_ClearPending((IRQ)i);
IRQ_Disable((IRQ)i);
}
__DSB();
__ISB();
__WFI();
MCU_Reset();
I checked the NVIC registers, and they are all set to 0, which should mean that all interrupts are disabled and there are no pending interrupts. However, everytime I execture the WFI (Wait for interrupt) instruction, it will just NOP on me.
Why can I not enter sleep mode? Do I actually have to somehow disable all of my peripherals and disable the interrupts at their source or is there a way to just mask all interrupts minus the CAN?
Thank you for your time. Let me know if there is anything I can do to clarify the question.
c embedded interrupt cortex-m3 lpc
asked Nov 10 at 18:40
LaneL
485519
|
show 3 more comments
up vote
1
down vote
favorite
Background: I am trying to make my embedded application go to sleep when there is no CAN activity with the __WFI() and then wake up whenever a CAN interrupt is received. Before enterring sleep mode, I disable all interrupts and clear their pending states in the NVIC registers.
To start, right now I'm just trying to make sure that I can sleep forever when I have all interrupts disabled.
for(int i = 0; i < IRQ_MAX; i++)
{
IRQ_ClearPending((IRQ)i);
IRQ_Disable((IRQ)i);
}
__DSB();
__ISB();
__WFI();
MCU_Reset();
I checked the NVIC registers, and they are all set to 0, which should mean that all interrupts are disabled and there are no pending interrupts. However, everytime I execture the WFI (Wait for interrupt) instruction, it will just NOP on me.
Why can I not enter sleep mode? Do I actually have to somehow disable all of my peripherals and disable the interrupts at their source or is there a way to just mask all interrupts minus the CAN?
Thank you for your time. Let me know if there is anything I can do to clarify the question.
c embedded interrupt cortex-m3 lpc
asked Nov 10 at 18:40
LaneL
485519
Are you stepping through the code with a debugger?
– Fiddling Bits
Nov 10 at 18:51
@FiddlingBits yes, but I have tried with the debugger disconnected as well and it is the same behavior.
– LaneL
Nov 10 at 18:54
5
The reason I'm asking is because the debugger may be preventing the device from sleeping.
– Fiddling Bits
Nov 10 at 18:55
1
This code won't disableSysTick, because that does not go through theNVICat all.
– Turbo J
Nov 11 at 10:29
@TurboJ that could expain it. I know for sure that SysTick is still being used by the RTOS, but I thought that the WFI instruction only pertained to NVIC interrupts.I will try and see what it would take to disable the SysTick and if that works.
– LaneL
Nov 12 at 15:18
|
show 3 more comments
up vote
1
down vote
favorite
up vote
1
down vote
favorite
Background: I am trying to make my embedded application go to sleep when there is no CAN activity with the __WFI() and then wake up whenever a CAN interrupt is received. Before enterring sleep mode, I disable all interrupts and clear their pending states in the NVIC registers.
To start, right now I'm just trying to make sure that I can sleep forever when I have all interrupts disabled.
for(int i = 0; i < IRQ_MAX; i++)
{
IRQ_ClearPending((IRQ)i);
IRQ_Disable((IRQ)i);
}
__DSB();
__ISB();
__WFI();
MCU_Reset();
I checked the NVIC registers, and they are all set to 0, which should mean that all interrupts are disabled and there are no pending interrupts. However, everytime I execture the WFI (Wait for interrupt) instruction, it will just NOP on me.
Why can I not enter sleep mode? Do I actually have to somehow disable all of my peripherals and disable the interrupts at their source or is there a way to just mask all interrupts minus the CAN?
Thank you for your time. Let me know if there is anything I can do to clarify the question.
c embedded interrupt cortex-m3 lpc
asked Nov 10 at 18:40
LaneL
485519
Background: I am trying to make my embedded application go to sleep when there is no CAN activity with the __WFI() and then wake up whenever a CAN interrupt is received. Before enterring sleep mode, I disable all interrupts and clear their pending states in the NVIC registers.
To start, right now I'm just trying to make sure that I can sleep forever when I have all interrupts disabled.
for(int i = 0; i < IRQ_MAX; i++)
{
IRQ_ClearPending((IRQ)i);
IRQ_Disable((IRQ)i);
}
__DSB();
__ISB();
__WFI();
MCU_Reset();
I checked the NVIC registers, and they are all set to 0, which should mean that all interrupts are disabled and there are no pending interrupts. However, everytime I execture the WFI (Wait for interrupt) instruction, it will just NOP on me.
Why can I not enter sleep mode? Do I actually have to somehow disable all of my peripherals and disable the interrupts at their source or is there a way to just mask all interrupts minus the CAN?
Thank you for your time. Let me know if there is anything I can do to clarify the question.
c embedded interrupt cortex-m3 lpc
c embedded interrupt cortex-m3 lpc
asked Nov 10 at 18:40
LaneL
485519
asked Nov 10 at 18:40
LaneL
485519
asked Nov 10 at 18:40
LaneL
485519
asked Nov 10 at 18:40
LaneL
485519
asked Nov 10 at 18:40
LaneL
485519
485519
Are you stepping through the code with a debugger?
– Fiddling Bits
Nov 10 at 18:51
@FiddlingBits yes, but I have tried with the debugger disconnected as well and it is the same behavior.
– LaneL
Nov 10 at 18:54
5
The reason I'm asking is because the debugger may be preventing the device from sleeping.
– Fiddling Bits
Nov 10 at 18:55
1
This code won't disableSysTick, because that does not go through theNVICat all.
– Turbo J
Nov 11 at 10:29
@TurboJ that could expain it. I know for sure that SysTick is still being used by the RTOS, but I thought that the WFI instruction only pertained to NVIC interrupts.I will try and see what it would take to disable the SysTick and if that works.
– LaneL
Nov 12 at 15:18
|
show 3 more comments
Are you stepping through the code with a debugger?
– Fiddling Bits
Nov 10 at 18:51
@FiddlingBits yes, but I have tried with the debugger disconnected as well and it is the same behavior.
– LaneL
Nov 10 at 18:54
5
The reason I'm asking is because the debugger may be preventing the device from sleeping.
– Fiddling Bits
Nov 10 at 18:55
1
This code won't disableSysTick, because that does not go through theNVICat all.
– Turbo J
Nov 11 at 10:29
@TurboJ that could expain it. I know for sure that SysTick is still being used by the RTOS, but I thought that the WFI instruction only pertained to NVIC interrupts.I will try and see what it would take to disable the SysTick and if that works.
– LaneL
Nov 12 at 15:18
Are you stepping through the code with a debugger?
– Fiddling Bits
Nov 10 at 18:51
Are you stepping through the code with a debugger?
– Fiddling Bits
Nov 10 at 18:51
@FiddlingBits yes, but I have tried with the debugger disconnected as well and it is the same behavior.
– LaneL
Nov 10 at 18:54
@FiddlingBits yes, but I have tried with the debugger disconnected as well and it is the same behavior.
– LaneL
Nov 10 at 18:54
5
5
The reason I'm asking is because the debugger may be preventing the device from sleeping.
– Fiddling Bits
Nov 10 at 18:55
The reason I'm asking is because the debugger may be preventing the device from sleeping.
– Fiddling Bits
Nov 10 at 18:55
1
1
This code won't disable
SysTick, because that does not go through the NVIC at all.– Turbo J
Nov 11 at 10:29
This code won't disable
SysTick, because that does not go through the NVIC at all.– Turbo J
Nov 11 at 10:29
@TurboJ that could expain it. I know for sure that SysTick is still being used by the RTOS, but I thought that the WFI instruction only pertained to NVIC interrupts.I will try and see what it would take to disable the SysTick and if that works.
– LaneL
Nov 12 at 15:18
@TurboJ that could expain it. I know for sure that SysTick is still being used by the RTOS, but I thought that the WFI instruction only pertained to NVIC interrupts.I will try and see what it would take to disable the SysTick and if that works.
– LaneL
Nov 12 at 15:18
|
show 3 more comments
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Are you stepping through the code with a debugger?
– Fiddling Bits
Nov 10 at 18:51
@FiddlingBits yes, but I have tried with the debugger disconnected as well and it is the same behavior.
– LaneL
Nov 10 at 18:54
5
The reason I'm asking is because the debugger may be preventing the device from sleeping.
– Fiddling Bits
Nov 10 at 18:55
1
This code won't disable
SysTick, because that does not go through theNVICat all.– Turbo J
Nov 11 at 10:29
@TurboJ that could expain it. I know for sure that SysTick is still being used by the RTOS, but I thought that the WFI instruction only pertained to NVIC interrupts.I will try and see what it would take to disable the SysTick and if that works.
– LaneL
Nov 12 at 15:18