main.h File Reference
Detailed Description
Defines and prototypes for main.c.
- Application note:
- AVR351: Runtime calibration and compensation of RC oscillators using the Oscillator Sampling Interface
- Documentation
- For comprehensive code documentation, supported compilers, compiler settings and supported devices see readme.html
- Revision
- 4809
- Date
- 2008-11-04 12:17:59 +0100 (ti, 04 nov 2008)
Copyright (c) 2008, Atmel Corporation All rights reserved.
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2. Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution.
3. The name of ATMEL may not be used to endorse or promote products derived from this software without specific prior written permission.
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Definition in file main.h.
#include <ioavr.h>
#include <inavr.h>
#include <stdint.h>
Go to the source code of this file.
Defines | |
| #define | BANDGAP_ADJ_DELAY BANDGAP_WAIT_us*SYSTEM_CLK_MHz |
| Delay to avoid brown-out scaled to system clock cycles. See appnote for details. | |
| #define | BANDGAP_WAIT_us 20 |
| Wait between each update of BGCCR to avoid brown-out. Given in hole microseconds (from datasheet). | |
| #define | BUTTON_MASK 0x0E |
| Use pin 1-3 for input, and skip pin 0 and 4-7. | |
| #define | BUTTON_ONE 1 |
| #define | BUTTON_THREE 3 |
| #define | BUTTON_TWO 2 |
| #define | FAILED -1 |
| #define | NO_BUTTON 0 |
| #define | SUCCESS 0 |
| #define | VTEMP 0x04 |
| VADMUX setting for VTEMP measurement. | |
Functions | |
| int8_t | InitBandgap (void) |
| Bandgap initialisation. | |
| uint16_t | MeasureTemperature (void) |
| Temperature measurement. | |
| int8_t | ReadButtons (void) |
| Read what/if buttons was pressed. | |
Define Documentation
| #define BANDGAP_ADJ_DELAY BANDGAP_WAIT_us*SYSTEM_CLK_MHz |
Delay to avoid brown-out scaled to system clock cycles. See appnote for details.
Definition at line 70 of file main.h.
Referenced by InitBandgap().
| #define BANDGAP_WAIT_us 20 |
| #define BUTTON_MASK 0x0E |
Use pin 1-3 for input, and skip pin 0 and 4-7.
Definition at line 58 of file main.h.
Referenced by ReadButtons().
| #define BUTTON_ONE 1 |
| #define BUTTON_THREE 3 |
| #define BUTTON_TWO 2 |
| #define FAILED -1 |
Definition at line 56 of file main.h.
Referenced by CalibrateFastRCruntime(), InitBandgap(), and ReadButtons().
| #define SUCCESS 0 |
| #define VTEMP 0x04 |
VADMUX setting for VTEMP measurement.
Definition at line 64 of file main.h.
Referenced by MeasureTemperature().
Function Documentation
| int8_t InitBandgap | ( | void | ) |
Bandgap initialisation.
Initialises the bandgap voltage reference to factory calibration. If second calibration has been done at room temperature those values are loaded. BGCCR need to be changed slowly to avoid BOD. See appnote for details.
- Return values:
-
FAILED Loading of signature data failed. ROOM_TEMPERATURE Signature data for second insertion test found. HOT_TEMPERATURE Signature data only for first insertion test found.
< Factory calibration of BGCCR and BGCRR.
Definition at line 185 of file main.c.
References BANDGAP_ADJ_DELAY, FAILED, HOT_TEMPERATURE, READ_SIGNATUREBYTE, ROOM_TEMPERATURE, SIG_BGCCR_CALIB_25C, SIG_BGCCR_CALIB_HOT, and SIG_BGCRR_CALIB_25C.
Referenced by main().
00186 { 00188 uint8_t bgccr_cal, bgcrr_cal; 00189 int8_t mode; 00190 00191 bgcrr_cal = READ_SIGNATUREBYTE(SIG_BGCRR_CALIB_25C); 00192 00193 /* Uncomment the following line to do second point calibration. Please notice 00194 * that breaking within 2 cycles of completing a signature byte reading will 00195 * corrupt AVR Studio flash readout. 00196 */ 00197 // bgcrr_cal = 0xFF; 00198 00199 // Check that valid BGCRR data exists in the signature row. 00200 if ( bgcrr_cal != 0xFF ){ 00201 bgccr_cal = 0x3F & READ_SIGNATUREBYTE(SIG_BGCCR_CALIB_25C); 00202 mode = ROOM_TEMPERATURE; 00203 }else{ 00204 // No valid data was found. Load HOT temperature data and abort if that is not valid. 00205 bgcrr_cal = 0x0F; 00206 bgccr_cal = 0x3F & READ_SIGNATUREBYTE(SIG_BGCCR_CALIB_HOT); 00207 00208 if (bgccr_cal == 0x3F) { 00209 return FAILED; 00210 } 00211 00212 mode = HOT_TEMPERATURE; 00213 } 00214 00215 BGCRR = bgcrr_cal; 00216 00217 // If done this way device may enter BOD so use method below. 00218 // BGCCR = bgccr_cal; 00219 00220 // Adjust BGCCR up if needed. Slowly to avoid BOD. 00221 while (BGCCR < bgccr_cal) { 00222 BGCCR++; 00223 __delay_cycles(BANDGAP_ADJ_DELAY); 00224 } 00225 00226 /* Adjust down if necessary. (Safe with regard to BOD, but uses 00227 * longer time to stabilize and thus give correct ADC measurements) 00228 */ 00229 BGCCR = bgccr_cal; 00230 00231 return mode; 00232 }
| uint16_t MeasureTemperature | ( | void | ) |
Temperature measurement.
Returns temperature in Kelvin (uint16_t). Absolute accuracy of the temperature sensor is stated at +/-5 Kelvin in the data sheet.
An alternative could be to use °C with 1 byte signed format, thus giving a range of +127 - -128°C. In an application temperature measurements should be part of the VADC interrupt controlled measurements.
- Returns:
- temperature [Kelvin] (uint16_t)
Definition at line 247 of file main.c.
References temp_sensor_coeff, and VTEMP.
Referenced by main().
00248 { 00249 uint32_t temperature; 00250 00251 // VTEMP as input 00252 VADMUX = VTEMP; 00253 00254 temperature = VADC; 00255 00256 // Enable VADC and start conversion 00257 VADCSR = (1 << VADEN) | (1 << VADSC) | (1 << VADCCIF); 00258 00259 do {} while(!(VADCSR & (1 << VADCCIF))); 00260 00261 temperature = VADC; 00262 temperature *= temp_sensor_coeff; 00263 00264 // Disable VADC and reset interrupt flag, interrupting any ongoing conversion 00265 VADCSR = (1 << VADCCIF); 00266 return ((uint16_t)(temperature >> 14)); 00267 }
| int8_t ReadButtons | ( | void | ) |
Read what/if buttons was pressed.
Uses PB1/2/3 as inputs, so they must be configured as inputs (default when device is reset). Waits for button(s) to be released before returning the result.
- Returns:
- Which button was pressed, or FAILED if none or multiple was pressed.
Definition at line 147 of file main.c.
References BUTTON_MASK, BUTTON_ONE, BUTTON_THREE, BUTTON_TWO, and FAILED.
Referenced by main().
00148 { 00149 uint8_t buttons_pressed; 00150 int8_t return_value; 00151 buttons_pressed = (~PINB & BUTTON_MASK); 00152 00153 do {} while (~PINB & BUTTON_MASK); 00154 00155 switch( buttons_pressed ) { 00156 case (1 << BUTTON_ONE): 00157 return_value = BUTTON_ONE; 00158 break; 00159 case (1 << BUTTON_TWO): 00160 return_value = BUTTON_TWO; 00161 break; 00162 case (1 << BUTTON_THREE): 00163 return_value = BUTTON_THREE; 00164 break; 00165 default : 00166 return_value = FAILED; 00167 break; 00168 } 00169 00170 return return_value; 00171 }
