Техника микропроцессорных систем в коммутации. Проектирование микропроцессорных систем на базе микроконтроллеров AVR фирмы Atmel. Горохин В.Н. - 34 стр.

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67
Ʌɚɛɨɪɚɬɨɪɧɚɹ ɪɚɛɨɬɚ ʋ 6
ɉɊɈȽɊȺɆɆɂɊɈȼȺɇɂȿ ȺɇȺɅɈȽɈ-ɐɂɎɊɈȼɈȽɈ
ɉɊȿɈȻɊȺɁɈȼȺɌȿɅə ɆɂɄɊɈɄɈɇɌɊɈɅɅȿɊɈȼ
ɐɟɥɶ ɪɚɛɨɬɵ: ɂɡɭɱɟɧɢɟ ɢ ɨɫɜɨɟɧɢɟ ɦɟɬɨɞɢɤɢ ɩɪɨɝɪɚɦɦɢɪɨɜɚɧɢɹ ɚɧɚɥɨɝɨ-
ɰɢɮɪɨɜɨɝɨ ɩɪɟɨɛɪɚɡɨɜɚɬɟɥɹ ɦɢɤɪɨɤɨɧɬɪɨɥɥɟɪɨɜ.
Ʉɪɚɬɤɢɟ ɬɟɨɪɟɬɢɱɟɫɤɢɟ ɫɜɟɞɟɧɢɹ.
ɍɩɪɚɜɥɟɧɢɟ ɚɧɚɥɨɝɨ-ɰɢɮɪɨɜɵɦ ɩɪɟɨɛɪɚɡɨɜɚɬɟɥɟɦ
Ɇɢɤɪɨɤɨɧɬɪɨɥɥɟɪ ATmega16 ɨɫɧɚɳɟɧ 10-ɪɚɡɪɹɞɧɵɦ ADC ɩɨɫɥɟɞɨɜɚɬɟɥɶ-
ɧɵɯ ɩɪɢɛɥɢɠɟɧɢɣ (ɪɢɫ. 24). ADC ɩɨɞɫɨɟɞɢɧɟɧ ɤ 10-ɤɚɧɚɥɶɧɨɦɭ ɚɧɚɥɨɝɨɜɨɦɭ
ɦɭɥɶɬɢɩɥɟɤɫɨɪɭ (MUX), ɩɨɡɜɨɥɹɸɳɟɦɭ ɩɨɞɚɬɶ ɧɚ ɜɯɨɞ ɩɪɟɨɛɪɚɡɨɜɚɬɟɥɹ ɥɸɛɨɣ
ɢɡ ɜɨɫɶɦɢ ɜɯɨɞɧɵɯ ɫɢɝɧɚɥɨɜ ɫɨ ɜɯɨɞɨɜ ADC0…. ADC7, ɥɢɛɨ ɷɬɚɥɨɧɧɨɟ ɧɚɩɪɹ-
ɠɟɧɢɟ 1,22 ȼ, ɥɢɛɨ ɫɢɝɧɚɥ ɫɨ ɜɯɨɞɚ AGND. ȼɵɜɨɞ AGND ɪɟɤɨɦɟɧɞɭɟɬɫɹ ɩɨɞ-
ɫɨɟɞɢɧɢɬɶ ɤ ɬɨɱɤɟ c ɧɭɥɟɜɵɦ ɩɨɬɟɧɰɢɚɥɨɦ GND. ADC ɫɨɞɟɪɠɢɬ ɫɯɟɦɭ ɜɵɛɨɪ-
ɤɢ/ɯɪɚɧɟɧɢɹ SH.
Ɋɢɫ. 24. ɋɬɪɭɤɬɭɪɚ ɚɧɚɥɨɝɨ-ɰɢɮɪɨɜɨɝɨ ɩɪɟɨɛɪɚɡɨɜɚɬɟɥɹ
Ɋɟɡɭɥɶɬɚɬ AD ɩɪɟɨɛɪɚɡɨɜɚɧɢɹ ɜ ɜɢɞɟ 10-ɛɢɬɧɨɝɨ ɞɜɨɢɱɧɨɝɨ ɱɢɫɥɚ D ɪɚɜɟɧ:
ɝɞɟ U – ɜɯɨɞɧɨɟ ɧɚɩɪɹɠɟɧɢɟ, a U
o
– ɨɩɨɪɧɨɟ ɧɚɩɪɹɠɟɧɢɟ ɩɪɟɨɛɪɚɡɨɜɚ-
ɬɟɥɹ.
ȼ ɤɚɱɟɫɬɜɟ ɢɫɬɨɱɧɢɤɚ ɨɩɨɪɧɨɝɨ ɧɚɩɪɹɠɟɧɢɹ ɩɪɟɨɛɪɚɡɨɜɚɬɟɥɹ ɦɨɠɧɨ ɢɫ-
ɩɨɥɶɡɨɜɚɬɶ ɜɧɟɲɧɢɣ ɫɢɝɧɚɥ ɫ ɜɵɜɨɞɚ AREF, ɜɧɭɬɪɟɧɧɢɣ ɢɫɬɨɱɧɢɤ 2,56 ȼ, ɥɢɛɨ
ɧɚɩɪɹɠɟɧɢɟ ɩɢɬɚɧɢɹ ɚɧɚɥɨɝɨɜɨɣ ɱɚɫɬɢ ɦɢɤɪɨɤɨɧɬɪɨɥɥɟɪɚ ɫ ɜɵɜɨɞɚ AVCC.
Ⱦɥɹ ɭɩɪɚɜɥɟɧɢɹ ɩɪɟɨɛɪɚɡɨɜɚɬɟɥɟɦ ɜ ɦɢɤɪɨɤɨɧɬɪɨɥɥɟɪɟ ɢɫɩɨɥɶɡɭɸɬɫɹ ɪɟ-
ɝɢɫɬɪɵ (ɪɢɫ. 25):
68
0
Ɋɟɝɢɫɬɪ ɭɩɪɚɜɥɟɧɢɹ ɦɭɥɶɬɢɩɥɟɤɫɨɪɨɦ ADMUX
0
Ɋɟɝɢɫɬɪ ɭɩɪɚɜɥɟɧɢɹ ɚɧɚɥɨɝɨ-ɰɢɮɪɨɜɵɦ ɩɪɟɨɛɪɚɡɨɜɚɬɟɥɟɦ ADCSR
0
Ɋɟɝɢɫɬɪɵ ɞɚɧɧɵɯ ADCL ɢ ADCH
0
Ɋɟɝɢɫɬɪ ɫɨɫɬɨɹɧɢɹ ɦɢɤɪɨɤɨɧɬɪɨɥɥɟɪɚ SREG
Ɋɢɫ. 25. Ɋɟɝɢɫɬɪɵ, ɢɫɩɨɥɶɡɭɟɦɵɟ ɚɧɚɥɨɝɨ-ɰɢɮɪɨɜɵɦ ɩɪɟɨɛɪɚɡɨɜɚɬɟɥɟɦ
Ⱥɧɚɥɨɝɨ-ɰɢɮɪɨɜɨɣ ɩɪɟɨɛɪɚɡɨɜɚɬɟɥɶ ɦɨɠɟɬ ɪɚɛɨɬɚɬɶ ɜ ɞɜɭɯ ɪɟɠɢɦɚɯ: ɪɟ-
ɠɢɦɟ ɨɞɧɨɤɪɚɬɧɨɝɨ ɩɪɟɨɛɪɚɡɨɜɚɧɢɹ ɢ ɜ ɰɢɤɥɢɱɟɫɤɨɦ ɪɟɠɢɦɟ. ȼɵɛɨɪ ɪɟɠɢɦɚ
ɩɪɨɢɡɜɨɞɢɬɫɹ ɛɢɬɨɦ ADFR ɪɟɝɢɫɬɪɚ ADCSR.
Ɋɚɛɨɬɚ ɚɧɚɥɨɝɨ-ɰɢɮɪɨɜɨɝɨ ɩɪɟɨɛɪɚɡɨɜɚɬɟɥɹ ɪɚɡɪɟɲɚɟɬɫɹ ɭɫɬɚɧɨɜɤɨɣ ɜ ɫɨ-
ɫɬɨɹɧɢɟ 1 ɛɢɬɚ ADEN ɜ ɪɟɝɢɫɬɪɟ ADCSR. ɉɪɟɨɛɪɚɡɨɜɚɧɢɟ ɧɚɱɢɧɚɟɬɫɹ ɫ ɭɫɬɚ-
ɧɨɜɤɢ ɜ ɫɨɫɬɨɹɧɢɟ 1 ɛɢɬɚ ɧɚɱɚɥɚ ɩɪɟɨɛɪɚɡɨɜɚɧɢɹ ADSC
ɉɨɫɤɨɥɶɤɭ ɚɧɚɥɨɝɨ-ɰɢɮɪɨɜɨɣ ɩɪɟɨɛɪɚɡɨɜɚɬɟɥɶ ɮɨɪɦɢɪɭɟɬ 10-ɪɚɡɪɹɞɧɵɣ
ɪɟɡɭɥɶɬɚɬ, ɬɨ ɩɨ ɡɚɜɟɪɲɟɧɢɢ ɩɪɟɨɛɪɚɡɨɜɚɧɢɹ ɪɟɡɭɥɶɬɢɪɭɸɳɢɟ ɞɚɧɧɵɟ ɪɚɡɦɟ-
ɳɚɸɬɫɹ ɜ ɞɜɭɯ ɪɟɝɢɫɬɪɚɯ ɞɚɧɧɵɯ ADCH ɢ ADCL.
Ⱥɧɚɥɨɝɨ-ɰɢɮɪɨɜɨɣ ɩɪɟɨɛɪɚɡɨɜɚɬɟɥɶ ɢɦɟɟɬ ɫɜɨɟ ɫɨɛɫɬɜɟɧɧɨɟ ɩɪɟɪɵɜɚɧɢɟ
ADC (ɜɟɤɬɨɪ $1ɋ), ɤɨɬɨɪɨɟ ɦɨɠɟɬ ɛɵɬɶ ɚɤɬɢɜɢɡɢɪɨɜɚɧɨ ɩɨ ɡɚɜɟɪɲɟɧɢɸ ɩɪɟɨɛ-
ɪɚɡɨɜɚɧɢɹ. Ʉɨɝɞɚ ɨɛɪɚɳɟɧɢɟ ɤ ɪɟɝɢɫɬɪɚɦ ɡɚɩɪɟɳɟɧɨ, ɜ ɩɪɨɰɟɫɫɟ ɫɱɢɬɵɜɚɧɢɹ ɪɟ-
ɝɢɫɬɪɨɜ ADCL ɢ ADCH, ɩɪɟɪɵɜɚɧɢɟ ɛɭɞɟɬ ɚɤɬɢɜɢɡɢɪɨɜɚɬɶɫɹ, ɞɚɠɟ ɩɪɢ ɩɨɬɟɪɟ
ɪɟɡɭɥɶɬɚɬɚ.
Ɋɟɝɢɫɬɪ ADMUX ɩɪɟɞɧɚɡɧɚɱɟɧ ɞɥɹ ɭɩɪɚɜɥɟɧɢɹ ɜɯɨɞɧɵɦ ɚɧɚɥɨɝɨɜɵɦ
ɦɭɥɶɬɢɩɥɟɤɫɨɪɨɦ.
0
Ȼɢɬɵ 7 ɢ 6 – REFS1..0 – ɨɛɟɫɩɟɱɢɜɚɸɬ ɜɵɛɨɪ ɷɬɚɥɨɧɧɨɝɨ ɧɚɩɪɹɠɟɧɢɹ ɧɚ
ɜɯɨɞɟ AREF ɚɧɚɥɨɝɨ-ɰɢɮɪɨɜɨɝɨ ɩɪɟɨɛɪɚɡɨɜɚɬɟɥɹ. ȼɵɛɨɪ ɩɪɨɢɡɜɨɞɢɬɫɹ ɜ ɫɨɨɬ-
ɜɟɬɫɬɜɢɢ ɫ ɬɚɛɥɢɰɟɣ 28.
Ɍɚɛɥɢɰɚ 28. ȼɵɛɨɪ ɢɫɬɨɱɧɢɤɚ ɨɩɨɪɧɨɝɨ ɧɚɩɪɹɠɟɧɢɹ ADC
REFS1 REFS0 ȼɵɛɨ
ɪ
ɢɫɬɨɱɧɢɤɚ ɧɚɩ
ɪ
ɹɠɟɧɢɹ
0 0 AREF
,
ɜɧ
ɭ
ɬ
ɪ
ɟɧɧɟɟ ɧɚɩ
ɪ
ɹɠɟɧɢɟ Vref ɨɬɤɥɸɱɟɧɨ
0 1 AVCC ɫ ɜɧɟɲɧɢɦ ɤɨɧ
ɞ
ɟɧɫɚɬɨ
ɪ
ɨɦ ɧɚ ɤɨɧɬɚɤɬɟ AREF
1 0 Ɋɟɡɟ
ɪ
ɜ
1 1 ȼɧɭɬɪɟɧɧɢɣ ɢɫɬɨɱɧɢɤ 2.56 ȼ ɫ ɜɧɟɲɧɢɦ ɤɨɧɞɟɧɫɚɬɨɪɨɦ ɧɚ AREF
0
Ȼɢɬ 5 - ADLAR – ɜɨɡɞɟɣɫɬɜɭɟɬ ɧɚ ɡɚɩɢɫɶ ɪɟɡɭɥɶɬɚɬɚ ɜ ɪɟɝɢɫɬɪɵ ɞɚɧɧɵɯ
ADCL ɢ ADCH. ɉɪɢ ADLAR=0 ɦɨɠɧɨ ɢɫɩɨɥɶɡɨɜɚɬɶ ɭɩɪɨɳɟɧɧɨɟ 8-ɛɢɬɧɨɟ ɩɪɟ-
ɨɛɪɚɡɨɜɚɧɢɟ.

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