Hello!
I'm having a very weird problem with a K65. The behavior I'm seeing is different based on wether optimizations are enabled and/or JTAG is connected.
Here are the details:
| | Code Compiled with Any Optimization Level Enabled | Code Compiled with Optimizations Disabled |
|---|
| JTAG Connected | K65 boots fine. Voltage on RESET pin is equal to our system voltage of 2.1V (read on multimeter). | K65 boots fine. Voltage on RESET pin is equal to our system voltage of 2.1V (read on multimeter). |
| JTAG Disconnected | K65 boots fine. Voltage on RESET pin is equal to our system voltage of 2.1V (read on multimeter). | K65 does not boot. Voltage on RESET pin is read on multimeter to be at 1.2V. Proving the RESET line on oscilloscope shows that the reset line is behaving like a square wave that keeps toggling between high and low. So the K65 keeps resetting. |
I was able to track down a small part of the code that if I optimized individually, I no longer see the issue. That part of the code is the 2 functions NVIC_SetPriority() and NVIC_EnableIRQ() which are only used in an enable_interrupt() function:
void enable_interrupt(uint8_t irqNum, uint8_t prio)
{
NVIC_SetPriority(irqNum, prio);
NVIC_ClearPendingIRQ(irqNum);
NVIC_EnableIRQ(irqNum);
}
NVIC_SetPriority() and NVIC_EnableIRQ() are from the Freescale KSDK 1.3 and I haven't modified them:
__STATIC_INLINE void NVIC_SetPriority(IRQn_Type IRQn, uint32_t priority)
{
if((int32_t)IRQn < 0) {
SCB->SHP[(((uint32_t)(int32_t)IRQn) & 0xFUL)-4UL] = (uint8_t)((priority << (8 - __NVIC_PRIO_BITS)) & (uint32_t)0xFFUL);
}
else {
NVIC->IP[((uint32_t)(int32_t)IRQn)] = (uint8_t)((priority << (8 - __NVIC_PRIO_BITS)) & (uint32_t)0xFFUL);
}
}
__STATIC_INLINE void NVIC_EnableIRQ(IRQn_Type IRQn)
{
NVIC->ISER[(((uint32_t)(int32_t)IRQn) >> 5UL)] = (uint32_t)(1UL << (((uint32_t)(int32_t)IRQn) & 0x1FUL));
}
So if I optimize these 2 functions only with the reset of my code unoptimized and JTAG disconnected, the K65 boots fine and the RESET line voltage goes to 2.1V. I do that by adding __attribute__((optimize("O1"))) to both function definitions:
__attribute__((optimize("O1"))) __STATIC_INLINE void NVIC_SetPriority(IRQn_Type IRQn, uint32_t priority)
{
if((int32_t)IRQn < 0) {
SCB->SHP[(((uint32_t)(int32_t)IRQn) & 0xFUL)-4UL] = (uint8_t)((priority << (8 - __NVIC_PRIO_BITS)) & (uint32_t)0xFFUL);
}
else {
NVIC->IP[((uint32_t)(int32_t)IRQn)] = (uint8_t)((priority << (8 - __NVIC_PRIO_BITS)) & (uint32_t)0xFFUL);
}
}
__attribute__((optimize("O1"))) __STATIC_INLINE void NVIC_EnableIRQ(IRQn_Type IRQn)
{
NVIC->ISER[(((uint32_t)(int32_t)IRQn) >> 5UL)] = (uint32_t)(1UL << (((uint32_t)(int32_t)IRQn) & 0x1FUL));
}
Any help would be greatly appreciated!
