Thiết kế vôn kế với 8051

B¸o c¸o §Ò tµi. S¬ ®å thiÕt kÕ phÇn cøng: L1 L2 L3 l1 l2 l3 D1 vcc LED-GREEN R2 330 1 J2 U1 VI DIODE VO 3 X1 C2 19 33p CRYSTAL 18 XTAL1 XTAL2 2 2 1 GND D3 CONN-H2 R1 9 10k K1 RST C3 K1 29 30 31 10u PSEN ALE EA U2 cs rd wr C4 R3 150p 10k +PROBE int 1 2 3 4 5 8 10 9 19 6 7 R4 CS RD WR CLK IN INTR A GND D GND VREF/2 CLK R VCC DB0(LSB) DB1 DB2 DB3 DB4 DB5 DB6 DB7(MSB) 20 18 17 16 15 14 13 12 11 VIN+ VIN- 1 2 3 4 5 6 7 8 P1.0/T2 P1.1/T2EX P1.2 P1.3 P1.4 P1.5 P1.6 P1.7 P0.0/AD0 P0.1/AD1 P0.2/AD2 P0.3/AD3 P0.4/AD4 P0.5/AD5 P0.6/AD6 P0.7/AD7 P2.0/A8 P2.1/A9 P2.2/A10 P2.3/A11 P2.4/A12 P2.5/A13 P2.6/A14 P2.7/A15 P3.0/RXD P3.1/TXD P3.2/INT0 P3.3/INT1 P3.4/T0 P3.5/T1 P3.6/WR P3.7/RD com a b c d e f g dp com R6 R7 R8 10k R9 10k R10 10k R11 10k R12 10k R13 10k 39 38 37 36 35 34 33 32 10k 10k 21 22 23 24 25 26 27 28 10 11 12 13 14 15 16 17 a b c d e f g dp a b c d e f g dp 33p 7805 com C1 U3 R14 4k7 Q1 PNP Q2 R15 4k7 PNP R16 Q3 PNP 4k7 int cs wr rd AT89C52 ADC0804 100k R5 200k -PROBE C5 33p PhÇn xö lý trung t©m ®iÒu khiÓn bëi VDK AT89S52. PhÇn thu nhËn, chuyÓn ®æi sè t¬ng tù dïng IC ADC0804. D¶i th«ng cña ADC0804 lµ 0-5v. §Ó ®o ®iÖn ¸p cao h¬n ta dïng ®iÖn trë ®Ó ph©n ¸p. Víi kiÓu bè trÝ ®iÖn trë ph©n ¸p nh trªn h×nh ta cã: Uvmax = UADCmax.(R4+R5)/R4 Víi th«ng sè nh h×nh vÏ ta cã Uvmax = 16V. §é ph©n gi¶i lµ: 19/256 = 0.0625V PhÇn hiÓn thÞ dïng 3 LED 7 thanh. 3 LED nµy dïng chung cæng d÷ liÖu P0, thùc hiÖn thuËt to¸n quÐt led ®Ó hiÓn thÞ. KÝch dßng cho c¸c LED nµy lµ 3 Tranzitor NPN A1015. ThuËt to¸n quÐt 3 LED 7 thanh: Gi¶ sö ta cÇn hiÓn thÞ sè ABC lªn 3 LED 7 thanh: §Çu tiªn ®a m· 7 ®o¹n hiÓn thÞ ký tù A lªn P0, më cæng P2 thÝch hîp ®Ó chØ më Tranzitor ®iÒu khiÓn LED thø 3 s¸ng. Nh vËy d÷ liÖu trªn Data Bus thuéc vÒ LED 3. Sau ®ã ®a m· 7 ®o¹n hiÓn thÞ ký tù B lªn P0.... cø xoay trßn nh vËy trong vßng lÆp tèc ®é cao ta hiÓn thÞ ®îc sè cÇn dïng. ThuËt to¸n gi¶i m· tÝn hiÖu: Víi ®é ph©n gi¶i lµ 0.0625 ta suy ra ®iÖn ¸p ®o ®îc sau khi qua biÕn ®æi ADC lµ: ABC = Adc*0.0625 (Trong ®ã ABC lµ gi¸ trÞ ®iÖn ¸p, adc lµ gi¸ trÞ gi¶i m· ®Çu ra cña ADC0804). §Ó thu ®îc tõng sè ABC riªng rÏ ta cã: A = ABC chia lÊy nguyªn cho 100; B = (ABC – A*100) chia lÊy nguyªn cho 10; C = (ABC – A*100 – B*10). Sau khi thu ®îc A,B,C ta dÔ dµng hiÓn thÞ ®îc trªn LED 7 ®o¹n. Sau ®©y lµ phÇn mÒm ®iÒu khiÓn: #include sbit rd=P3^7; //Read signal P3.7 sbit wr=P3^6; //Write signal P3.6 sbit cs=P3^5; //Chip Select P3.5 sbit intr= P3^4; //INTR signal P3.4 int array[10]={0xc0,0xF9,0xA4,0xB0,0x99,0x92,0x82,0xf8,0x80,0x90}; sbit dp=P0^7; sbit led0=P2^0; sbit led1=P2^1; sbit led2=P2^2; unsigned int adc_avg,adc; void delay() { unsigned int i; for(i=1;i