During the reboxing, I connected the power to test again, and got that puff of smoke from the Nano that augers bad news all around.
Now I just get the power light and nothing else, so I think that Nano has had it! I’m hoping it was the rubber band pushing a wire on the board into another one causing a short, as I had done no work on the boards themselves. I’ll only know when I program a new Nano and put it in the board, I suppose…
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#define aref_voltage 3.3 int min_temp = 30; int max_temp = 50; int led = 13; //Optional output LED int temp = A0; //Middle pin of tmp36 thermistor int blinkDuration = 0; unsigned long lastBlinkTime; boolean blinkOn = false; volatile byte half_revolutions; unsigned int rpm; long rpmLastTime = 0; long senseDelay = 0; int workInterval = 1000; float tempC; int fanPWM = 10; int fanDutyCycle = 0; int fanTransistor = 7; /* Bubble Declarations */ int datapin = 4; int clockpin = 5; int latchpin = 6; const int db = 10; const int CapC = 11; const int blank = 12; const int cathodesOn = 4; const int cathodesOff = 5; //int cathodes[] = {8, 9, 10, 11}; byte digits[] = { 0b11111100, // 0 0b01100000, // 1 0b11011010, // 2 0b11110010, // 3 0b01100110, // 4 0b10110110, // 5 0b10111110, // 6 0b11100000, // 7 0b11111110, // 8 0b11110110, // 9 0b00000001, // decimal point (11) 0b10011100, // Letter C (12) 0b00000000 // Blank }; byte cathodes[] = { 0b11111110, // 1 0b11111101, // 2 0b11111011, // 3 0b11110111, // 4 0b11111111, //cathodes on (all led's off) 0b00000000 //cathodes off }; /* flag to decide whether to show temp or RPM, flips every second */ bool isTemp = true; void rpm_interrupt() { half_revolutions++; //Each rotation, this interrupt function is run twice } // the setup routine runs once when you press reset: void setup() { analogReference(EXTERNAL); //Sets the AREF pin to 3.3V // initialize serial communication at 9600 bits per second: Serial.begin(9600); pinMode(fanPWM, OUTPUT); pinMode(fanTransistor, OUTPUT); pinMode(led, OUTPUT); //Make A0 the analogue thermistor input pinMode(temp, INPUT); // function 'rpm' will be called when the rpm_sense pin goes high attachInterrupt(0, rpm_interrupt, FALLING); half_revolutions = 0; rpm = 0; // Bubble Setup pinMode(datapin, OUTPUT); pinMode(clockpin, OUTPUT); pinMode(latchpin, OUTPUT); digitalWrite(datapin, HIGH); digitalWrite(clockpin, HIGH); digitalWrite(latchpin, HIGH); //set the timer variables rpmLastTime = millis(); lastBlinkTime = millis(); } // the loop routine runs over and over again forever: void loop() { long actualTicks = half_revolutions; //depending on the speed of the fan, the blink rate is 'mapped' to a different scale //so when the rate goes from 85-255, the blink millisecond time goes from 500-25 //The faster the fan, the shorter the duration, so the faster the blink effect blinkDuration = map(fanDutyCycle, 85, 255, 500, 25); cathodesHigh(); // reset bubble display //Do the LED flashing // blinkOn is effectively the same as fanOn - the transistor is open if (blinkOn) { if (isTemp) { displayTemp(tempC); } else { displayRPM(rpm); } if (millis() - lastBlinkTime >= blinkDuration) { digitalWrite(led, !digitalRead(led)); lastBlinkTime = millis(); } } else { if (digitalRead(led) == HIGH) { digitalWrite(led, LOW); } } //PWM Sensing long timeElapsed = (millis() - senseDelay); if (timeElapsed > workInterval) { //this code only fires every second //RPM work detachInterrupt(0); rpm = actualTicks * 30; //two ticks per rev half_revolutions = 0; attachInterrupt(0, rpm_interrupt, FALLING); isTemp = !isTemp; //Do temperature work //This should possibly be done outside the 1 second block, and averaged to smooth the results int tempreading = analogRead(temp); float temp_v = tempreading * aref_voltage; //3.3V temp_v /= 1024.0; Serial.write("TEMP_V: "); Serial.print(temp_v); Serial.write("V\n"); tempC = (temp_v - 0.5) * 100; Serial.write("TEMP: "); Serial.print(tempC); Serial.write(" degrees C\n"); fanDutyCycle = map(constrain(tempC, min_temp, max_temp), min_temp, max_temp, 80, 255); // This is the clever bit - because the constrain is mapped to 80 - 255, then // when the temp is on or below min_temp, then the contrains sets the value to 80, which is NOT enough to get // into the if > 85 block just below //Fan Speed analogWrite(fanPWM, fanDutyCycle); if (fanDutyCycle >= 85) { blinkOn = true; digitalWrite(fanTransistor, HIGH); Serial.println("Transistor High"); } else { blinkOn = false; digitalWrite(fanTransistor, LOW); Serial.println("Transistor Low"); } senseDelay = millis(); } delay(1); // delay in between reads for stability } void cathodesHigh() { writeByte(cathodes[cathodesOn], digits[blank]); } void writeByte(byte cathode, byte data) { shiftOut(datapin, clockpin, LSBFIRST, cathode); shiftOut(datapin, clockpin, LSBFIRST, data); // toggle the latch pin so that the data appears as an output digitalWrite(latchpin, HIGH); digitalWrite(latchpin, LOW); } void displayTemp(float temp) { //make into whole number int tempTemp = (round(temp * 10) / 10.0) * 10; int pos = 1; while (tempTemp) { int digit = tempTemp % 10; if (pos == 2) { writeByte(cathodes[pos], digits[digit] + 1); } else { writeByte(cathodes[pos], digits[digit]); } tempTemp /= 10; pos ++; delay(1); } //letter C writeByte(cathodes[0], digits[CapC]); delay(1); } void displayRPM(int rpm) { int rpmTemp = rpm; int pos = 0; while (rpmTemp) { int digit = rpmTemp % 10; writeByte(cathodes[pos], digits[digit]); delay(5); rpmTemp /= 10; pos ++; } } |
To connect to the Bubble Display module, I mounted it on a piece of Veroboard, with the rails cut between the 2×6 pins. I left one row of extra holes on each side, and mounted some 90 degree header strip there, exposing the 12 pins at right angles to the display. I then took two length of 6 strand ribbon cable, put 6 way Molex connectors on for plugging into the display. But on the other end of the ribbon, I put 12 individual connectors on, this way, it was easy to match the bubble pin number with the correct shift register and pin at the board end. I do need to find some nice soft flexible cable though, all the stuff I seem to have is really stiff, and doesnt like being bent at certain angles!
I love it when things work first time. This wasn’t one of those occasions though! I had a problem where all of the output pins of the 2nd shift register were always high, meaning no digits on the display. It took some work with the voltage tester, but it was tracked down to a minute piece of stray solder, bridging two strips on the veroboard.
So the project is complete, barring the enclosure (currently the two boards are being held together by an elastic band with a piece of hard plastic in between!). So when I find a suitable sized enclosure, I’ll transfer it into there, but in the meantime, I’ll put up the board layout for the extra board, and the full code, once I add some comments.
There are just 2 points of connection between the original board and the new bubble display board. A twin connector to the ground and 5V on the bottom right, and a triple for the data, clock and latch. Fortunately there were three unused outputs from the Nano with unused rails. That’s the 2nd red box at the top.
Here is the first step for part two of my cooling project. It uses just 3 outputs to drive a pair of shift registers, and ultimately a 4-digit bubble display!
Currently the display toggles between displaying 24.5C and 1496 (the RPM)… Why? Because those are the two hard coded values I’ve picked in my function calls!
Given its only 3 pins, my plan is to put it all on a different bit of Veroboard, and connect it to the original board with a plug! Exciting stuff 🙂
