added example varDutyT1

master
M. Stokroos 3 years ago
parent e6abcc2b3a
commit 05242cd306
  1. 11
      README.md
  2. 127
      sketches/varDutyT1/varDutyT1.ino

@ -5,10 +5,10 @@ This repository contains Arduino sketches and Arduino libraries maintained by th
## Sketches
- **Blinky**
**Blinky**
A hello world example used to play along with Git.
- **Nexus_Omni4WD**
**Nexus_Omni4WD**
Firmware for the Nexus Omni4WD wheel base for setting the wheel speeds independently. It is used to control the robot under ROS.
![ ](figures/NexusOmni4WD.png "Nexus Omni 4WD")
@ -24,14 +24,17 @@ The Arduino controller 10009 with io expansion shield on the Omni4WD is Duemila
*extra/nexuscontrol*
Script for controlling the Nexus with ROS.
- **RoFish**
**RoFish**
A CPG-based locomotion control example of a robotic fish.
![ ](figures/animation.gif "Robotic Fish")
- **adaptiveFreqOsc**
**adaptiveFreqOsc**
An adaptive frequency oscillator example with Arduino.
**varDutyT1**
A sketch for varying (modulating) the duty-cycle of the PWM on the UNO-output pins 9 and 10 via the analog A0 input. The PWM frequency and update rate(!) = 15.625kHz. Resolution is 10-bits.
## Libraries
Currently there are no libraries available.

@ -0,0 +1,127 @@
/*
* File: varDutyT1.ino
* Purpose: Varying the duty-cycle of the PWM on output pins 9 and 10 via the analog A0 input. Update rate: 15.625kHz, resolution: 10-bits.
*
* Version: 1.0.0
*
* By: M. Stokroos
*
* Date: 02-12-2019
*
*/
// Library to be included for fast digital I/O when observing the timing with an oscilloscope.
//#include <digitalWriteFast.h> // library for high performance digital reads and writes by jrraines
// see http://www.arduino.cc/cgi-bin/yabb2/YaBB.pl?num=1267553811/0
// and http://code.google.com/p/digitalwritefast/
#define LPERIOD 500000 // the main loop period time in us. In this case 500ms.
#define PIN_LED 13 // PLL locking status indicator LED
#define PIN_PWMA 9 // Timer1 OCR1A 10-bit PWM
#define PIN_PWMB 10 // Timer1 OCR1B 10-bit PWM
#define PIN_DEBUG 4 // test output pin
// global vars
volatile int adcVal;
unsigned long nextLoop;
// ******************************************************************
// Setup
// ******************************************************************
void setup(){
cli(); // disable interrupts
pinMode(PIN_LED, OUTPUT);
pinMode(PIN_PWMA, OUTPUT);
pinMode(PIN_PWMB, OUTPUT);
pinMode(PIN_DEBUG, OUTPUT);
// initialize ADC for continuous sampling mode
DIDR0 = 0x3F; // digital inputs disabled for ADC0D to ADC5D
bitSet(ADMUX, REFS0); // Select Vcc=5V as the ADC reference voltage
bitClear(ADMUX, REFS1);
bitClear(ADMUX, MUX0); // selecting ADC CH# 0
bitClear(ADMUX, MUX1);
bitClear(ADMUX, MUX2);
bitClear(ADMUX, MUX3);
bitSet(ADCSRA, ADEN); // AD-converter enabled
bitSet(ADCSRA, ADATE); // auto-trigger enabled
bitSet(ADCSRA, ADIE); // ADC interrupt enabled
bitSet(ADCSRA, ADPS0); // ADC clock prescaler set to 128
bitSet(ADCSRA, ADPS1);
bitSet(ADCSRA, ADPS2);
bitClear(ADCSRB, ACME); // Analog Comparator (ADC)Multiplexer enable OFF
bitClear(ADCSRB, ADTS0); // triggered by Timer/Counter1 Overflow
bitSet(ADCSRB, ADTS1);
bitSet(ADCSRB, ADTS2);
bitSet(ADCSRA, ADSC); // start conversion
/* configuring TIMER1 for PWM-mode 7 */
// prescaler = 1:
bitSet(TCCR1B, CS10);
bitClear(TCCR1B, CS11);
bitClear(TCCR1B, CS12);
// mode 7:
bitSet(TCCR1A, WGM10);
bitSet(TCCR1A, WGM11);
bitSet(TCCR1B, WGM12);
bitClear(TCCR1B, WGM13);
//set output compare
bitClear(TCCR1A, COM1A0); // Compare Match PWM 9
bitSet(TCCR1A, COM1A1);
bitSet(TCCR1A, COM1B0); // Compare Match PWM 10 - inverted channel
bitSet(TCCR1A, COM1B1);
// enable TIMER1 compare interrupt
bitSet(TIMSK1, TOIE1); // enable Timer1 Interrupt
sei(); // global enable interrupts
nextLoop = micros() + LPERIOD; // Set the loop timer variable for the next loop interval.
}
// ******************************************************************
// Main loop
// ******************************************************************
void loop(){
// do nothing here except for flashing the LED...
digitalWrite(PIN_LED, !digitalRead(PIN_LED));
while(nextLoop > micros()); // wait until the end of the time interval
nextLoop += LPERIOD; // set next loop time at current time + LOOP_PERIOD
}
/* ******************************************************************
* ADC ISR. The ADC is triggered by Timer1.
* *******************************************************************/
ISR(ADC_vect){
//digitalWriteFast(PIN_DEBUG, HIGH); //for checking the interrupt frequency
// read the current ADC input channel
adcVal=ADCL; // store low byte
adcVal+=ADCH<<8; // store high byte
// write out 10bit PWM output registers A&B (pin9 and pin10).
OCR1AH = adcVal>>8; //MSB
OCR1AL = adcVal; //LSB
//(inverted) output:
OCR1BH = OCR1AH; //MSB
OCR1BL = OCR1AL; //LSB
//digitalWriteFast(PIN_DEBUG, LOW);
}
/* ******************************************************************
* Timer1 ISR
*********************************************************************/
ISR(TIMER1_OVF_vect) {
//empty ISR. Only used to trigger the ADC.
}
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