C\u00e1c ph\u1ea7n c\u1ea5u h\u00ecnh, kh\u1edfi t\u1ea1o, \u0111\u1ecdc k\u1ebft qu\u1ea3 ADC, … \u0111\u1ec1u \u0111\u01b0\u1ee3c vi\u1ebft th\u00e0nh c\u00e1c ch\u01b0\u01a1ng tr\u00ecnh con.
\nC\u00e1c ch\u00fa th\u00edch c\u1ea7n thi\u1ebft \u0111\u01b0\u1ee3c vi\u1ebft \u0111\u1ea7y \u0111\u1ee7 \u0111\u1ec3 c\u00f3 th\u1ec3 d\u1ec5 d\u00e0ng ch\u1ec9nh s\u1eeda c\u1ea5u h\u00ecnh khi c\u1ea7n.<\/em><\/span><\/p>\n\/****************************************************************<\/pre>\n*<\/pre>\n* www.payitforward.edu.vn<\/pre>\n*<\/pre>\n****************************************************************\/<\/pre>\n\/****************************************************************<\/pre>\n*<\/pre>\n* PIC Training Course<\/pre>\n*<\/pre>\n****************************************************************\/<\/pre>\n\/****************************************************************\r\n*\r\n* Module : adc_main.c\r\n* Description : Read ADC from AN3 channel\r\n* If ADC_result > 2.5V then Turn On LEDs\r\n* Tool : HI-TECH PIC\r\n* Chip : 16F887\r\n* History : 05\/03\/2011\r\n*\r\n* Author : Nguyen Tien Manh, CLB NCKH\r\n* Notes :\r\n*\r\n*\r\n****************************************************************\/<\/pre>\n\/****************************************************************\r\n* IMPORT\r\n****************************************************************\/<\/pre>\n#include\r\n__CONFIG(XT & WDTDIS & PWRTEN & MCLREN & UNPROTECT & SWBOREN &\r\nIESODIS & FCMDIS & LVPDIS & DEBUGDIS); \/\/1st config. Word<\/pre>\n__CONFIG(BORV21); \/\/2st config. Word<\/pre>\n#define _XTAL_FREQ 4000000<\/pre>\n\/****************************************************************\r\n* EXTERN\r\n****************************************************************\/\r\n\/*none...*\/<\/pre>\n\/*****************************************************************\r\nGLOBAL VARIABLE\r\n******************************************************************\/\r\n\/*none...*\/<\/pre>\n\/*****************************************************************\r\n* ROUTINES\r\n******************************************************************\/\r\nvoid port_init()\r\n{\r\nANSEL = 0x08; \/\/ Chon kenh ADC AN3\r\nANSELH = 0;\r\nTRISA3 = 1; \/\/RA3 phai la Input de doc ADC\r\nTRISB = 0; \/\/PortB de xuat LED nen la OutPut\r\nPORTB = 0xFF \/\/ Tat het LED o portB\r\n}<\/pre>\n\/\/----------------------------------------------------------------\r\nvoid adc_init()\r\n{\r\n\/\/ ADC conversion clock: = Fosc\/8\r\n\/\/ ADCS <1:0> = 00 Fosc\/2\r\n\/\/ ADCS <1:0> = 01 Fosc\/8\r\n\/\/ ADCS <1:0> = 10 Fosc\/32\r\n\/\/ ADCS <1:0> = 11 F_RC\r\nADCS1 = 0;\r\nADCS0 = 1;<\/pre>\n\/\/ Voltage reference: Internal Vref\r\n\/\/ VCFG <1:0> = 00 Internal Vref\r\n\/\/ VCFG <1:0> = 11 External Vref\r\nVCFG1 = 0;\r\nVCFG0 = 0;<\/pre>\n\/\/ Select Input chanel: AN3\r\n\/\/ CHS <3:0> = 0000 Select AN0\r\n\/\/ CHS <3:0> = 0001 Select AN1\r\n\/\/ CHS <3:0> = 0010 Select AN2\r\n\/\/ ...\r\n\/\/ CHS <3:0> = 1101 Select AN13\r\nCHS3 = 0;\r\nCHS2 = 0;\r\nCHS1 = 1;\r\nCHS0 = 1;<\/pre>\n\/\/ Result format: Right\r\n\/\/ ADFM = 1 Right justified\r\n\/\/ ADFM = 0 Left justified\r\nADFM = 1;<\/pre>\n\/\/ Turn on ADC Module\r\nADON = 1;<\/pre>\n\/\/delay to wait for adc module init.\r\n__delay_ms (1);\r\n}<\/pre>\n\/\/----------------------------------------------------------------\r\n\/\/interrupt initialization\r\nvoid int_init()\r\n{\r\nGIE = 1; \/\/Global Interrupt Enable\r\nPEIE = 1; \/\/Peripheral Interrupt Enable\r\nADIE = 1; \/\/ADC Interrupt Enable\r\nADIF = 0; \/\/Clear ADC Interrupt Flag\r\n}<\/pre>\n\/\/----------------------------------------------------------------\r\n\/\/Interrupt service rountine\r\nvoid interrupt isr()\r\n{\r\nint ADC_result;\r\nif (PEIE && ADIE && ADIF)\r\n{\r\nADIF = 0; \/\/Clear ADC Interrupt Flag<\/pre>\n\/\/Read ADC result\r\nADC_result = (ADRESH<<8)|ADRESL;\r\n\/\/V_in > 2.5V <=> ADC_result > 512\r\nif (ADC_result> 512)\r\n{\r\nPORTB = 0; \/\/Turn LEDs ON\r\n}\r\nelse\r\n{\r\nPORTB = 0xFF;\r\n}\r\n}\r\n}<\/pre>\n\/****************************************************************\r\n* MAIN\r\n****************************************************************\/<\/pre>\n\/* -- void main (void) -----------------------------------------\r\n*\r\n* Description : Configure port, adc module and enable interrupt\r\n* then wait for ADC interrupt\r\n* Parameters : none\r\n* Return : don't care\r\n* Notes :\r\n*\/<\/pre>\nvoid main(void)\r\n{\r\nport_init();\r\nadc_init();\r\nint_init();\r\nwhile(1)\r\n{\r\n__delay_us(50); \/\/delay between 2 AD conversions\r\nGODONE = 1; \/\/Set GODONE bit to start conversion\r\n};\r\n}<\/pre>\n\/****************************************************************\r\n* END OF adc_main.c\r\n****************************************************************\/<\/pre>\n5. B\u00e0i t\u1eadp:<\/strong><\/span><\/p>\n\u0110\u1ecdc gi\u00e1 tr\u1ecb \u0111i\u1ec7n \u00e1p (0-5V) t\u1eeb 1 ch\u00e2n ADC c\u1ee7a PIC v\u00e0 hi\u1ec3n th\u1ecb k\u1ebft qu\u1ea3 l\u00ean LCD, v\u1edbi – \u0110\u1ecdc gi\u00e1 tr\u1ecb ADC t\u1eeb ch\u00e2n AN3 (gi\u00e1 tr\u1ecb n\u00e0y n\u1eb1m trong ph\u1ea1m vi 0-1023)
\n– T\u00ednh to\u00e1n ra gi\u00e1 tr\u1ecb \u0111i\u1ec7n \u00e1p (Volt) th\u1ef1c t\u1ebf?
\n– Gi\u00e1 tr\u1ecb \u0111i\u1ec7n \u00e1p n\u00e0y y\u00eau c\u1ea7u l\u1ea5y t\u1edbi 3 ch\u1eef s\u1ed1 th\u1eadp ph\u00e2n: 0.000
\n– Hi\u1ec3n th\u1ecb k\u1ebft qu\u1ea3 l\u00ean LCD.
\nV\u00ed d\u1ee5: <\/strong>“V_in = 1.352 V”<\/p>\n(Tham kh\u1ea3o th\u00eam ch\u01b0\u01a1ng tr\u00ecnh h\u1ecdc tr\u00ean forum<\/a>)<\/p>\n","protected":false},"excerpt":{"rendered":"T\u00e0i li\u1ec7u n\u00e0y \u0111\u01b0\u1ee3c bi\u00ean so\u1ea1n kh\u00f4ng nh\u1eb1m v\u00e0o b\u1ea5t k\u1ef3 m\u1ee5c \u0111\u00edch n\u00e0o mang t\u00ednh th\u01b0\u01a1ng m\u1ea1i. B\u1ea1n c\u00f3 quy\u1ec1n sao ch\u00e9p, s\u1eeda ch\u1eefa v\u00e0 ph\u00e2n ph\u00e1t b\u1eb1ng b\u1ea5t k\u1ef3 h\u00ecnh th\u1ee9c n\u00e0o. H\u00e3y s\u1eed d\u1ee5ng t\u00e0i li\u1ec7u n\u00e0y, s\u1eeda ch\u1eefa, b\u1ed5 sung v\u00e0 g\u1eedi cho nh\u1eefng ai c\u1ea7n n\u00f3. Ch\u00fang t\u00f4i kh\u00f4ng \u0111\u1ec1 t\u00ean t\u00e1c gi\u1ea3 bi\u00ean so\u1ea1n. T\u00e0i li\u1ec7u n\u00e0y thu\u1ed9c quy\u1ec1n s\u1edf h\u1eefu nh\u1eefng ai \u0111ang d\u00f9ng n\u00f3. Pay it forward\u2026 B\u00e0i 5: ADC 1. Chu\u1ea9n b\u1ecb ph\u1ea7n c\u1ee9ng: Trong b\u00e0i n\u00e0y ch\u00fang ta s\u1eed d\u1ee5ng bi\u1ebfn tr\u1edf k\u1ebft n\u1ed1i v\u1edbi 1 ch\u00e2n ADC c\u1ee7a PIC16F887. \u2026<\/p>\n
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![\"\"](\"http:\/\/i653.photobucket.com\/albums\/uu259\/rockc4\/CLB%2013112010\/PIC%20course\/ADCschematic.jpg\" "\\"ADC")