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Don't force projects to define interrupt priorities to fix CAN send #44

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Merged
merged 1 commit into from
Oct 8, 2025
Merged

Don't force projects to define interrupt priorities to fix CAN send #44

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26 changes: 22 additions & 4 deletions src/stm32_can.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -30,6 +30,13 @@
#include "stm32_can.h"
#include "cortex.h"

//Some functions use the "register" keyword which C++ doesn't like
//We can safely ignore that as we don't even use those functions
#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Wregister"
#include <libopencm3/cm3/cortex.h>
#pragma GCC diagnostic pop

#define MAX_INTERFACES 2
#define IDS_PER_BANK 4
#define EXT_IDS_PER_BANK 2
Expand All @@ -38,8 +45,19 @@
#define CAN_PERIPH_SPEED 36
#endif // CAN_PERIPH_SPEED

#ifndef CAN_MAX_IRQ_PRIORITY
#warning "CAN_MAX_IRQ_PRIORITY the highest interrupt priority users of the CAN interface may use is not defined"
// To allow concurrent sending of CAN frames from different contexts we need to
// disable interrupts. Some projects have hard realtime requirements which mean
// we cannot disable all interrupts. These projects should define the highest
// interrupt priority users of the CAN interface here. If not defined we assume
// that all interrupts can be disabled.
//
// CAN_MAX_IRQ_PRIORITY should match the priority passed to nvic_set_priority()
#ifdef CAN_MAX_IRQ_PRIORITY
#define DISABLE_CAN_USER_INTERRUPTS() cm_set_basepriority(CAN_MAX_IRQ_PRIORITY);
#define ENABLE_CAN_USER_INTERRUPTS() cm_set_basepriority(CM_BASEPRI_ENABLE_INTERRUPTS);
#else
#define DISABLE_CAN_USER_INTERRUPTS() cm_disable_interrupts()
#define ENABLE_CAN_USER_INTERRUPTS() cm_enable_interrupts()
#endif // CAN_MAX_IRQ_PRIORITY

struct CANSPEED
Expand Down Expand Up @@ -203,7 +221,7 @@ void Stm32Can::SetBaudrate(enum baudrates baudrate)
*/
void Stm32Can::Send(uint32_t canId, uint32_t data[2], uint8_t len)
{
cm_set_basepriority(CAN_MAX_IRQ_PRIORITY);
DISABLE_CAN_USER_INTERRUPTS();

can_disable_irq(canDev, CAN_IER_TMEIE);

Expand All @@ -222,7 +240,7 @@ void Stm32Can::Send(uint32_t canId, uint32_t data[2], uint8_t len)
can_enable_irq(canDev, CAN_IER_TMEIE);
}

cm_set_basepriority(CM_BASEPRI_ENABLE_INTERRUPTS);
ENABLE_CAN_USER_INTERRUPTS();
}

Stm32Can* Stm32Can::GetInterface(int index)
Expand Down