131 lines
3.3 KiB
C
Executable File
131 lines
3.3 KiB
C
Executable File
#include "main.h"
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// arrays to hold strings for LCD
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static char lm35_string[17];
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static char diode_string[17];
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/** @brief Initialises general pins for use.
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*
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* @note Does not initialise LCD pins. That is handled by lcdlibrary
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*/
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void pin_init() {
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/* Pin Mappings:
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* PC0 -> ADC0 input for diode measurement
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* PC1 -> ADC1 input for LM35
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*/
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// Pin Config for Diode ADC
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DDRC &= ~(1 << DDC0);
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DIDR0 |= (1 << ADC0D); // Disable digital input
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// Pin Config for LM35 ADC
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DDRC &= ~(1 << DDC1);
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DIDR0 |= (1 << ADC1D); // Disable digital input
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}
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/** @brief Initializes ADC with required settings
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*/
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void adc_init() {
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/* ADC Settings
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* Use 1v1 reference as Vref
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* Initially set input as GND
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* Data right-adjusted
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* No Interrupts
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*/
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// Set Vref
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ADMUX |= (1 << REFS1) | (1 << REFS0);
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// Set the clock prescaler to 128 (slower ADC means more accurate measurements)
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ADCSRA |= (1 << ADPS2) | (1 << ADPS1) | (1 << ADPS0);
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// Enable ADC
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ADCSRA |= (1 << ADEN);
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}
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/** @brief Blocking function to read an ADC conversion from a selected ADC input.
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*
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* @note Blocks until conversion finishes, so speed of this function is dependant
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* on ADC prescaler.
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*
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* @param adc_selection Value from 0-5, selects from ADC[0-5]
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*
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* @return Raw value of ADC conversion
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*/
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uint16_t adc_run_conversion(uint8_t adc_selection) {
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// Select ADC input, using
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ADMUX = (ADMUX & 0xF0) | (0x0F & adc_selection);
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// Start conversion
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ADCSRA |= (1 << ADSC);
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// Wait until conversion is complete
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while (!(ADCSRA & (1 << ADIF)));
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// Read out conversion value
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return ADC;
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}
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/** @brief Converts an ADC value from a measurement on an LM35 into a temperature.
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*
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* @param adc_reading Raw ADC measurement from LM35.
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*
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* @return Measured temperature, configure parameters in main.h
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*/
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int8_t lm35_convert(uint16_t adc_reading) {
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return (adc_reading * ADC_VREF / ADC_RESOLUTION) / LM35_SENSITIVITY;
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}
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/** @brief Converts and ADC value from a measurement on a diode into a temperature.
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*
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* @param adc_reading Raw ADC measurement from diode.
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*
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* @return Measured temperature, configure parameters in main.h
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*/
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int8_t diode_convert(uint16_t adc_reading) {
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int16_t value_diff = adc_reading - DIODE_VALUE_25C;
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int16_t temp_diff = value_diff / DIODE_SENSITIVITY;
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return temp_diff + 25;
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}
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int main() {
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// Initialise display
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// NOTE: LCD uses PB0-PB6
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lcd_init(LCD_DISP_ON);
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// Initialise peripherals
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pin_init();
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adc_init();
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while (1) {
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// Reset position
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lcd_gotoxy(0, 0);
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// Read LM35 value, and write to LCD
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uint16_t lm35_value = adc_run_conversion(1);
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int8_t lm35_temp = lm35_convert(lm35_value);
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// Convert measured value to string
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sprintf(lm35_string, "LM35 : %4d %3dC", lm35_value, lm35_temp);
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// Display temp on LCD
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lcd_puts((const char*) lm35_string);
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lcd_gotoxy(0, 1);
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// Read diode value, and write to
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uint16_t diode_value = adc_run_conversion(0);
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int8_t diode_temp = diode_convert(diode_value);
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sprintf(diode_string, "Diode: %4d %3dC", diode_value, diode_temp);
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// Display diode info on LCD
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lcd_puts((const char*) diode_string);
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// Refreshing too fast can make the data appear weird
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_delay_ms(500);
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}
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}
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