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Add mechanism to set SoftwareSerial interrupt priority #753

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Add mechanism to set SoftwareSerial interrupt priority #753

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10 changes: 10 additions & 0 deletions libraries/SoftwareSerial/src/SoftwareSerial.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -35,6 +35,7 @@
// Includes
//
#include "SoftwareSerial.h"
#include <timer.h>

#define OVERSAMPLE 3 // in RX, Timer will generate interruption OVERSAMPLE time during a bit. Thus OVERSAMPLE ticks in a bit. (interrupt not synchonized with edge).

Expand Down Expand Up @@ -96,6 +97,8 @@
// Statics
//
HardwareTimer SoftwareSerial::timer(TIMER_SERIAL);
const IRQn_Type SoftwareSerial::timer_interrupt_number = static_cast<IRQn_Type>(getTimerUpIrq(TIMER_SERIAL));
uint32_t SoftwareSerial::timer_interrupt_priority = NVIC_EncodePriority(NVIC_GetPriorityGrouping(), TIM_IRQ_PRIO, TIM_IRQ_SUBPRIO);
SoftwareSerial *SoftwareSerial::active_listener = nullptr;
SoftwareSerial *volatile SoftwareSerial::active_out = nullptr;
SoftwareSerial *volatile SoftwareSerial::active_in = nullptr;
Expand All @@ -107,6 +110,12 @@ uint32_t SoftwareSerial::rx_buffer = 0;
int32_t SoftwareSerial::rx_bit_cnt = -1; // rx_bit_cnt = -1 : waiting for start bit
uint32_t SoftwareSerial::cur_speed = 0;

void SoftwareSerial::setInterruptPriority(uint32_t preemptPriority, uint32_t subPriority)
{
timer_interrupt_priority = NVIC_EncodePriority(NVIC_GetPriorityGrouping(), preemptPriority, subPriority);
NVIC_SetPriority(timer_interrupt_number, timer_interrupt_priority);
}

//
// Private methods
//
Expand Down Expand Up @@ -134,6 +143,7 @@ void SoftwareSerial::setSpeed(uint32_t speed)
timer.setCount(0);
timer.attachInterrupt(&handleInterrupt);
timer.resume();
NVIC_SetPriority(timer_interrupt_number, timer_interrupt_priority);
} else {
timer.detachInterrupt();
}
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4 changes: 4 additions & 0 deletions libraries/SoftwareSerial/src/SoftwareSerial.h
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Original file line number Diff line number Diff line change
Expand Up @@ -66,6 +66,8 @@ class SoftwareSerial : public Stream {
// static data
static bool initialised;
static HardwareTimer timer;
static const IRQn_Type timer_interrupt_number;
static uint32_t timer_interrupt_priority;
static SoftwareSerial *active_listener;
static SoftwareSerial *volatile active_out;
static SoftwareSerial *volatile active_in;
Expand Down Expand Up @@ -118,6 +120,8 @@ class SoftwareSerial : public Stream {
return true;
}

static void setInterruptPriority(uint32_t preemptPriority, uint32_t subPriority);

using Print::write;
};

Expand Down