![]() For maximum resolution you should keep the frequency between 50 and 200kHz. With the bits ADPS2 to ADPS0 we can select a clock prescaler for the ADC. Now on the ADCSRA register: The ADEN bit will enable the ADC, with ADSC we can start a conversion. The bits MUX3 to MUX0 in the same register select one of the ADC pins for AD Conversion (We have only 1 ADC in the Atmega328P, but we can connect it to multiple ADC pins one after another). When we set the REFS1 and REFS0 bits in the ADMUX register to 01 we use Vcc as voltage reference, which is sufficient most of the time. First we want to set the reference voltage for our conversion. It has the SFRs ADMUX, ADCSRA, the convertion result registers ADCL and ADCH, and ADCSRB. The internal system clock runs at 16MHz on the Uno (you can do the math with the prescaler to calculate for the wanted frequency).ĪnalogRead aka ADC: For reading an analog voltage the ADC (Analog Digital Converter) is used. This sets the frequency range, that you have with the counter. With the bit values 0 1 1 you will get a prescaler of 64, so the timer will count up 1 every 64 clock pulses. With no prescaler the timer will count at every clock pulse. This determines how many clock pulses it needs to let the timer count 1 up. With these bits you can set the prescaler. You want to connect the timer to the internal system clock. Look at the corresponding table in the Timer1 register descriptions in the datasheet. A value of 0 for all bits means the timer is stopped. This is done by the clock selection bits CS10 to CS12 in the TCCR1B register. Thus it generates a square wave with variable frequency, that you can control by writing different values to the OCR1A register.īut we also need to configure the frequency with which the timer will count up. So in this mode, the timer will reset at a counter value that you set and will toggle the OC1A output pin for you. If you have set the COM1Ax bits in the TCCR1A register to the correct values, you can set it up to toggle the OC1A pin on a Compare Match). The timer will count up with the set frequency (will describe this later) until it gets to the value, that you wrote into the OCR1A register (Compare Match). ![]() You want the timer to be in CTC Mode (Clear Timer on Compare Match)(Waveform Generation Mode Bits set to 4, CTC mode for OCR1A). It has 3 control registers called TCCR1A to TCCR1C. The Uno has 3 Timers, where Timer0 is already configured by the Arduino IDE for functions like delay(), millis() and such. For hardware PWM you need to configure a Timer. Nonetheless you reach it with the same hardware. This is not the classical PWM use case (as you don't need to change the duty cycle but the frequency to get different tones). PWM: I think you want to use PWM for creating a tone from your buzzer. It contains detailed descriptions for almost every function and SFR of the microcontroller. Then the datasheet of the Atmega328P (the microcontroller on the Arduino Uno) is a must read for you. So I will give you hints and will point you to the corresponding registers. Doing this for the whole code is a rather big task for a single question on this site. But I guess this is an exercise to learn how to configure and use these peripherals yourself. In fact all the mentioned function calls are using the Special Function Registers (SFR) and thus the hardware peripherals of the Arduino in the background to work. Int value = analogRead(inPin) // read the value from the sensor 30.0) //<= on registers LiquidCrystal lcd(12, 11, 5, 4, 3, 2) //Digital pins to which you connect the LCD ![]() Having the following code that works for my setup: #include Also I have to use the registers instead of the function analogRead() that is reading from a temperature sensor. I have a little project at the university where I have to use the timers to generate a pwm signal and get it into a piezo buzzer when something else turns over a certain value by using the registers, the thing is that we have worked on some other microcontrollers so I don't really know the libraries for arduino uno with atmega328p and I would require some help on that.
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