我正在尝试将可正常编译的.ino草图转换为工作代码为C ++的类：
byte statusLed = 13;
byte sensorInterrupt = 0; // 0 = digital pin 2
byte sensorPin = 2;
// The hall-effect flow sensor outputs approximately 4.5 pulses per second per
// litre/minute of flow.
float calibrationFactor = 4.5;
volatile byte pulseCount;
float flowRate;
unsigned int flowMilliLitres;
unsigned long totalMilliLitres;
unsigned long oldTime;
void setup()
{
// Initialize a serial connection for reporting values to the host
Serial.begin(38400);
// Set up the status LED line as an output
pinMode(statusLed, OUTPUT);
digitalWrite(statusLed, HIGH); // We have an active-low LED attached
pinMode(sensorPin, INPUT);
digitalWrite(sensorPin, HIGH);
pulseCount = 0;
flowRate = 0.0;
flowMilliLitres = 0;
totalMilliLitres = 0;
oldTime = 0;
// The Hall-effect sensor is connected to pin 2 which uses interrupt 0.
// Configured to trigger on a FALLING state change (transition from HIGH
// state to LOW state)
attachInterrupt(sensorInterrupt, pulseCounter, FALLING);
}
/**
* Main program loop
*/
void loop()
{
if((millis() - oldTime) > 1000) // Only process counters once per second
{
// Disable the interrupt while calculating flow rate and sending the value to
// the host
detachInterrupt(sensorInterrupt);
// Because this loop may not complete in exactly 1 second intervals we calculate
// the number of milliseconds that have passed since the last execution and use
// that to scale the output. We also apply the calibrationFactor to scale the output
// based on the number of pulses per second per units of measure (litres/minute in
// this case) coming from the sensor.
flowRate = ((1000.0 / (millis() - oldTime)) * pulseCount) / calibrationFactor;
// Note the time this processing pass was executed. Note that because we've
// disabled interrupts the millis() function won't actually be incrementing right
// at this point, but it will still return the value it was set to just before
// interrupts went away.
oldTime = millis();
// Divide the flow rate in litres/minute by 60 to determine how many litres have
// passed through the sensor in this 1 second interval, then multiply by 1000 to
// convert to millilitres.
flowMilliLitres = (flowRate / 60) * 1000;
// Add the millilitres passed in this second to the cumulative total
totalMilliLitres += flowMilliLitres;
unsigned int frac;
// Print the flow rate for this second in litres / minute
Serial.print("Flow rate: ");
Serial.print(int(flowRate)); // Print the integer part of the variable
Serial.print("."); // Print the decimal point
// Determine the fractional part. The 10 multiplier gives us 1 decimal place.
frac = (flowRate - int(flowRate)) * 10;
Serial.print(frac, DEC) ; // Print the fractional part of the variable
Serial.print("L/min");
// Print the number of litres flowed in this second
Serial.print(" Current Liquid Flowing: "); // Output separator
Serial.print(flowMilliLitres);
Serial.print("mL/Sec");
// Print the cumulative total of litres flowed since starting
Serial.print(" Output Liquid Quantity: "); // Output separator
Serial.print(totalMilliLitres);
Serial.println("mL");
// Reset the pulse counter so we can start incrementing again
pulseCount = 0;
// Enable the interrupt again now that we've finished sending output
attachInterrupt(sensorInterrupt, pulseCounter, FALLING);
}
}
/*
Insterrupt Service Routine
*/
void pulseCounter()
{
// Increment the pulse counter
pulseCount++;
}
我尝试进行以下转换：
.H文件：
class FlowSensor
{
public:
FlowSensor(int pin);
void begin();
void run();
private:
int _pin;
byte sensorInterrupt = 0; // 0 = digital pin 2
// The hall-effect flow sensor outputs approximately 4.5 pulses per second per
// litre/minute of flow.
float calibrationFactor = 4.5;
float flowRate;
unsigned int flowMilliLitres;
unsigned long totalMilliLitres;
unsigned long oldTime;
volatile unsigned long pulseCount;
//volatile byte pulseCount;
void pulseCounter();
};
和C文件：
FlowSensor::FlowSensor(int pin)
{
_pin = pin;
}
void FlowSensor::begin()
{
pinMode(_pin, INPUT);
digitalWrite(_pin, HIGH);
pulseCount = 0;
flowRate = 0.0;
flowMilliLitres = 0;
totalMilliLitres = 0;
oldTime = 0;
sensorInterrupt = digitalPinToInterrupt(_pin);
// The Hall-effect sensor is connected to pin 2 which uses interrupt 0.
// Configured to trigger on a FALLING state change (transition from HIGH
// state to LOW state)
attachInterrupt(sensorInterrupt, pulseCounter, FALLING);
}
void FlowSensor::run()
{
if ((millis() - oldTime) > 1000) // Only process counters once per second
{
// Disable the interrupt while calculating flow rate and sending the value to
// the host
detachInterrupt(sensorInterrupt);
// Because this loop may not complete in exactly 1 second intervals we calculate
// the number of milliseconds that have passed since the last execution and use
// that to scale the output. We also apply the calibrationFactor to scale the output
// based on the number of pulses per second per units of measure (litres/minute in
// this case) coming from the sensor.
flowRate = ((1000.0 / (millis() - oldTime)) * pulseCount) / calibrationFactor;
// Note the time this processing pass was executed. Note that because we've
// disabled interrupts the millis() function won't actually be incrementing right
// at this point, but it will still return the value it was set to just before
// interrupts went away.
oldTime = millis();
// Divide the flow rate in litres/minute by 60 to determine how many litres have
// passed through the sensor in this 1 second interval, then multiply by 1000 to
// convert to millilitres.
flowMilliLitres = (flowRate / 60) * 1000;
// Add the millilitres passed in this second to the cumulative total
totalMilliLitres += flowMilliLitres;
unsigned int frac;
// Print the flow rate for this second in litres / minute
Serial.print("Flow rate: ");
Serial.print(int(flowRate)); // Print the integer part of the variable
Serial.print("."); // Print the decimal point
// Determine the fractional part. The 10 multiplier gives us 1 decimal place.
frac = (flowRate - int(flowRate)) * 10;
Serial.print(frac, DEC); // Print the fractional part of the variable
Serial.print("L/min");
// Print the number of litres flowed in this second
Serial.print(" Current Liquid Flowing: "); // Output separator
Serial.print(flowMilliLitres);
Serial.print("mL/Sec");
// Print the cumulative total of litres flowed since starting
Serial.print(" Output Liquid Quantity: "); // Output separator
Serial.print(totalMilliLitres);
Serial.println("mL");
// Reset the pulse counter so we can start incrementing again
pulseCount = 0;
// Enable the interrupt again now that we've finished sending output
attachInterrupt(sensorInterrupt, pulseCounter, FALLING);
}
}
/*
* Interrupt Service Routine
*/
void FlowSensor::pulseCounter()
{
// Increment the pulse counter
pulseCount++;
}
我得到的错误是：
C:\Users\marcp\Dropbox\Arduino\FlowSensor\FlowSensor.cpp: In member function 'void FlowSensor::begin()':
C:\Users\marcp\Dropbox\Arduino\FlowSensor\FlowSensor.cpp:24:56: error: invalid use of non-static member function
attachInterrupt(sensorInterrupt, pulseCounter, FALLING);
^
C:\Users\marcp\Dropbox\Arduino\FlowSensor\FlowSensor.cpp: In member function 'void FlowSensor::run()':
C:\Users\marcp\Dropbox\Arduino\FlowSensor\FlowSensor.cpp:80:57: error: invalid use of non-static member function
attachInterrupt(sensorInterrupt, pulseCounter, FALLING);
应该标记为静态吗？
答案 0 :(得分：0)
ISR必须不返回任何内容且不接受任何参数。这就是ISR的规则。这只是规则，我想你不能改变。成员函数都带有伴随它们的不可见的“ this”。
考虑一下，如果您有多个此类的实例，则中断调用应从哪个实例进行？它不知道，这就是不能将成员函数用作ISR的原因。
您可以创建一个静态方法（以便所有实例共享）并将静态方法用作ISR，但是这样它就无法访问任何成员变量。或者，您可以在草图中编写一个ISR，以从类的正确实例中调用正确的方法。
但是您根本不能将成员函数用作ISR。这是违反规则的。