How can I have a conditional statement that performs two tasks? first one and then the other in a loop - c

Question

So I am trying to code a program in arduino that does a task for 2 minutes and then another task for 5 mins. first one and then the other in a loop until a different condition is met.
Ive been trying to do this with if statements and while loops but im getting lost in the time part i think
//Pneumatic feed system
double minute = 1000*60;
double vibTime = 2 * minute; //2 mins
//double vibTime = 5000;
double execTime = millis();
double waitTime = 5 * minute; //time waits between vibrating
//double waitTime = 10000;
void DoPneuFeed() {
//Serial.print("Delta:");
//Serial.println(millis()-execTime);
if(Temp_Data[T_9] < 500)
{
if(execTime + vibTime < millis())
{
//turn on vibration for 2 mins
execTime = millis();
Serial.println("VIBRATING");
}
if(execTime + waitTime < millis())
{
//turn off vibration for 5 mins
execTime = millis();
Serial.println("WAITING");
}
}
if(Temp_Data[T_9] > 500)
{
relayOff(3);
relayOff(7);
}
}
void PneuFeed()
{
if(execTime + vibTime > millis())
{
//air pressure open
relayOn(3);
//vibrator on
relayOn(7);
}
else if(execTime + waitTime > millis())
{
relayOff(3);
relayOff(7);
}
}
I want to turn on the vibration mode for 2 mins and then turn it off for 5 mins. as long as the Temp_Data(T_9) < 500. if it is greater than 500 it should stay off.

Answer 1

Without going into the specifics of your code (since I cannot build it to test.) I only have one quick suggestion:
Instead of using a series of if-then-else (or variations of it) consider using a state machine. Implementations often include use of a switch() inside a while(expression){...} loop. The following is a very simple example of how you might be able to do the steps you need in this construct:
(Note, this is a mix of C and pseudo code for illustration. It is close to compilable , but contains a few undefined items.)
typedef enum {
START,
SET_VIB,
CHECK_TEMP,
GET_TIME,
CLEANUP,
SLEEP,
MAX_STATE
}STATE;
enum {
IN_WORK,
FAILED,
SUCCESS
};
enum {// durations in minutes
MIN_2,
MIN_5,
MIN_10,
MAX_DUR// change/add durations as profile needs
};
const int dur[MAX_DUR] = {120, 300, 600};
int RunProcess(STATE state);
int main(void)
{
STATE state = START;
RunProcess(state);
return 0;
}
int RunProcess(STATE state)//Add arguments here for temperature,
{ //Sleep duration, Cycles, etc. so they are not hardcoded.
int status;
time_t elapsed = 0; //s
BOOL running = TRUE;
double temp, setpoint;
int duration;
time_t someMsValue;
while(running)
switch (state) {
case START:
//Power to oven
//Power to vibe
//initialize state and status variables
duration = dur[MIN_2];
state = SLEEP;
status = IN_WORK;
break;
case SET_VIB:
//test and control vibe
if(duration == dur[MIN_2])
{
duration = dur[MIN_5];
//& turn off vibe
}
else
{
duration = dur[MIN_2];
//& turn on vibe
}
//init elapsed
elapsed = 0;
status = IN_WORK;
state = CHECK_TEMP;
break;
case CHECK_TEMP:
//read temperature
if(temp < setpoint)
{
state = SLEEP;
status = IN_WORK;
}
else
{
state = CLEANUP;
status = SUCCESS;
}
break;
case GET_TIME:
elapsed = getTime();
if(elapsed > duration) state = SET_VIB;
else state = SLEEP;
status = IN_WORK;
break;
case CLEANUP:
//turn off heat
//turn off vibe
running = FALSE;
break;
case SLEEP:
Sleep(someMsValue);
state = GET_TIME;
status = IN_WORK;
break;
default:
// called with incorrect state value
// error message and exit
status = FAILED;
state = CLEANUP;
break;
}
return status;
}
Suggestion for improvement to this illustration:
Expand this code to read in a "profile" file. It could include such things as parameter values typical to your process, such as temperature profiles, vibration profiles, number of cycles, etc. With such information, all of the hard-coding used here as illustration could be replaced with run-time configurable parameters, allowing the system to use many different profiles
without having to recompile the executable each time.
Another state machine example.