Hello,
I am dying here. I have a simple timer ISR for what is called “Motors Under No Load”. Basically the point is to check the current sensors for a no-load condition since a load would imply high current and no load would imply low current. The issue is, when do I turn the motors back on? So if I turn the motors off because there is no load I now have to find out if a load is present. My quick fix was that I would pulse the motors to see if a load was present. Next issue: when I pulse the motors there’s in-rush current! So now the current is super-high and to the mc it thinks that a load is present. So, what I need to do is pulse the motors and wait for the current to stabilize before I read them. Should only take about 50 ms or so to do this but I can’t seem to write the motor enable pin high then delay for a moment and then read the current sensor pin.
If you have any ideas or suggestions all are welcome 
Don’t be too harsh on the code, it’s a work in progress. Just trying to make it work.
volatile uint8_t curr_state3 = 0;
volatile uint8_t curr_state1 = 0;
volatile uint8_t curr_state2 = 0;
volatile uint8_t curr_state4 = 0;
volatile uint8_t curr_state5 = 0;
volatile uint8_t curr_state6 = 0;
volatile boolean LED_state = LOW;
const uint8_t currentThreshold = 50;
volatile uint16_t currentReading1_1 = 0;
volatile uint16_t currentReading1_2 = 0;
volatile uint16_t currentReading1_3 = 0;
volatile uint16_t currentReadingave1 = 0;
volatile boolean nlclk = HIGH;
volatile boolean nlclk2 = HIGH;
#define LED_pin 46
#define M3CS A4 // Motor 3 Current Sensor
#define M1CS A1 // Motor 2 Current Sensor
#define M3EN 34 // Motor 3 Enable
#define M1EN 25 // Motor 2 Enable
#define M3INA 36 // Motor 3 Input A
#define M3INB 37 // Motor 3 Input B
#define M1INA 26 // Motor 2 Input A
#define M1INB 27 // Motor 2 Input B
#define M3PWM 6 // Motor 3 PWM Signal
#define M1PWM 7 // Motor 2 PWM Signal
void setup() {
Serial.begin(9600);
pinMode(LED_pin, OUTPUT);
pinMode(M1CS, INPUT);
pinMode(M1EN, OUTPUT);
pinMode(M1INA, OUTPUT);
pinMode(M1INB, OUTPUT);
pinMode(M1PWM, OUTPUT);
cli();//stop interrupts
//set timer5 interrupt at 0.25 Hz
TCCR5A = 0;// set entire TCCR2A register to 0
TCCR5B = 0;// same for TCCR2B
TCNT5 = 0;//initialize counter value to 0
// set compare match register for 1 Hz increments
OCR5A = 62496;// = (16*10^6) / (256) - 1 (must be <65536)
// turn on CTC mode with WGM52
// Set CS52 and CS50 bit for 1024 prescaler
TCCR5B |= (1 << CS52) | (1 << WGM52) | (1 << CS50);
// enable timer compare interrupt
TIMSK5 |= (1 << OCIE5A);
sei();//allow interrupts
delay(1000);
leftmotorsforward(250);
delay(1000);
}//end setup
ISR(TIMER5_COMPA_vect) { // Interrupts every second
// This routine takes about 600 uS and might upset the value from
// 6 wheel differential. Due to this, this ISR is only performed every second.
// Need to average values of currentReading to get a better estimate of current
// passing through motors.
// No-Load FSM for Motor 1
// State 0.1
nlclk = !nlclk;
if (nlclk == HIGH) {
nlclk2 = !nlclk2;
if (nlclk2 = HIGH) {
uint8_t next_state1;
if (curr_state1 == 0) {
// Check motors to see if they are under no load
currentReading1_1 = analogRead(M1CS);
currentReading1_2 = analogRead(M1CS);
currentReading1_3 = analogRead(M1CS);
currentReadingave1 = (currentReading1_1 + currentReading1_2 + currentReading1_3) / 3;
if (currentReadingave1 < currentThreshold) { // Go to state 1
digitalWrite(M1EN, LOW);
next_state1 = 1;
}
else {
next_state1 = 0; // Remain in state 0
}
}
// State 1.1
else {
// Apply power to motors and check if they are under load
digitalWrite(M1EN, HIGH);
uint16_t curr_time = millis();
uint16_t lapsedtime = 0;
while (lapsedtime < 200) {
uint16_t pres_time = millis();
lapsedtime = pres_time - curr_time;
}
currentReading1_1 = analogRead(M1CS);
currentReading1_2 = analogRead(M1CS);
currentReading1_3 = analogRead(M1CS);
currentReadingave1 = (currentReading1_1 + currentReading1_2 + currentReading1_3) / 3;
digitalWrite(M1EN, LOW);
if (currentReadingave1 < currentThreshold) { // Remain in State 1
next_state1 = 1;
}
else {
next_state1 = 0; // Otherwise go to state 0
digitalWrite(M1EN, HIGH);
}
}
curr_state1 = next_state1;
}
}
/*
// No-Load FSM for Motor 2
// State 0.2
if(curr_state2 == 0){
// Check motors to see if they are under no load
int currentReading2 = analogRead(currentPin2);
if (currentReading2 < currentThreshold){ // Go to state 1
motor_enable2 = 0;
next_state2 = 1;
}
else{next_state2 = 0;} // Remain in state 0
}
// State 1.1
else{
// Apply power to motors and check if they are under load
motor_enable2 = 1;
delayMicroseconds(10);
currentReading2 = analogRead(currentPin2);
if (currentReading2 < currentThreshold){ // Remain in State 1
motor_enable2 = 0;
next_state2 = 1;
}
else{next_state2 = 0;} // Otherwise go to state 0
}
curr_state2 = next_state2;
// No-Load FSM for Motor 3
// State 0.3
if(curr_state3 == 0){
// Check motors to see if they are under no load
int currentReading3 = analogRead(currentPin3);
if (currentReading3 < currentThreshold){ // Go to state 1
motor_enable3 = 0;
next_state3 = 1;
}
else{next_state3 = 0;} // Remain in state 0
}
// State 1.3
else{
// Apply power to motors and check if they are under load
motor_enable3 = 1;
delayMicroseconds(10);
currentReading3 = analogRead(currentPin3);
if (currentReading3 < currentThreshold){ // Remain in State 1
motor_enable3 = 0;
next_state3 = 1;
}
else{next_state3 = 0;} // Otherwise go to state 0
}
curr_state3 = next_state3;
// No-Load FSM for Motor 4
// State 0.4
if(curr_state4 == 0){
// Check motors to see if they are under no load
int currentReading4 = analogRead(currentPin4);
if (currentReading4 < currentThreshold){ // Go to state 1
motor_enable4 = 0;
next_state4 = 1;
}
else{next_state4 = 0;} // Remain in state 0
}
// State 1.4
else{
// Apply power to motors and check if they are under load
motor_enable4 = 1;
delayMicroseconds(10);
currentReading4 = analogRead(currentPin4);
if (currentReading4 < currentThreshold){ // Remain in State 1
motor_enable4 = 0;
next_state4 = 1;
}
else{next_state4 = 0;} // Otherwise go to state 0
}
curr_state4 = next_state4;
// No-Load FSM for Motor 5
// State 0.5
if(curr_state5 == 0){
// Check motors to see if they are under no load
int currentReading5 = analogRead(currentPin5);
if (currentReading5 < currentThreshold){ // Go to state 1
motor_enable5 = 0;
next_state5 = 1;
}
else{next_state5 = 0;} // Remain in state 0
}
// State 1.5
else{
// Apply power to motors and check if they are under load
motor_enable5 = 1;
delayMicroseconds(10);
currentReading5 = analogRead(currentPin5);
if (currentReading5 < currentThreshold){ // Remain in State 1
motor_enable5 = 0;
next_state5 = 1;
}
else{next_state5 = 0;} // Otherwise go to state 0
}
curr_state5 = next_state5;
// No-Load FSM for Motor 6
// State 0.6
if(curr_state6 == 0){
// Check motors to see if they are under no load
int currentReading6 = analogRead(currentPin6);
if (currentReading6 < currentThreshold){ // Go to state 1
motor_enable6 = 0;
next_state6 = 1;
}
else{next_state6 = 0;} // Remain in state 0
}
// State 1.6
else{
// Apply power to motors and check if they are under load
motor_enable6 = 1;
delayMicroseconds(10);
currentReading6 = analogRead(currentPin6);
if (currentReading6 < currentThreshold){ // Remain in State 1
motor_enable6 = 0;
next_state6 = 1;
}
else{next_state6 = 0;} // Otherwise go to state 0
}
curr_state6 = next_state6;
*/
}
void loop() {
Serial.println(currentReadingave1);
}
No_LoadISRPC.ino (6.96 KB)