====== skin <-> substrate <-> earth ====== {{:summit2011:geo_res1.jpg|}} {{:summit2011:ses.jpg|}} Overlaying the measurement of skin impedance/resistance with earth impedance by using the fingers as measurement probes within context of geophysical earth resistance measurement. Electrodes are replaced by fingers digging into the earth. A measurement of parallel impedance of earth and skin is obtained. Plotting of measurements on ad-hoc hand-drawn maps. ===== code: ===== /* with Nokia 3310 as output */ /* - notes: - 5 pins for NOKIA - sce, reset, dc, sdin,sclk - 4 pins for bridge (generate/test negative supply for op-amp) */ #define F_CPU 12000000UL // 12 MHz #include #include #include #include #include #include #define byte unsigned char #define LOW 0 #define HIGH 1 #define LCD_CMD 0 #define LCD_C LOW #define LCD_D HIGH #define LCD_X 84 #define LCD_Y 48 #define sbi(var, mask) ((var) |= (uint8_t)(1 << mask)) #define cbi(var, mask) ((var) &= (uint8_t)~(1 << mask)) void LcdWrite(byte dc, byte data); static const byte ASCII[][5] = { {0x00, 0x00, 0x00, 0x00, 0x00} // 20 ,{0x00, 0x00, 0x5f, 0x00, 0x00} // 21 ! ,{0x00, 0x07, 0x00, 0x07, 0x00} // 22 " ,{0x14, 0x7f, 0x14, 0x7f, 0x14} // 23 # ,{0x24, 0x2a, 0x7f, 0x2a, 0x12} // 24 $ ,{0x23, 0x13, 0x08, 0x64, 0x62} // 25 % ,{0x36, 0x49, 0x55, 0x22, 0x50} // 26 & ,{0x00, 0x05, 0x03, 0x00, 0x00} // 27 ' ,{0x00, 0x1c, 0x22, 0x41, 0x00} // 28 ( ,{0x00, 0x41, 0x22, 0x1c, 0x00} // 29 ) ,{0x14, 0x08, 0x3e, 0x08, 0x14} // 2a * ,{0x08, 0x08, 0x3e, 0x08, 0x08} // 2b + ,{0x00, 0x50, 0x30, 0x00, 0x00} // 2c , ,{0x08, 0x08, 0x08, 0x08, 0x08} // 2d - ,{0x00, 0x60, 0x60, 0x00, 0x00} // 2e . ,{0x20, 0x10, 0x08, 0x04, 0x02} // 2f / ,{0x3e, 0x51, 0x49, 0x45, 0x3e} // 30 0 ,{0x00, 0x42, 0x7f, 0x40, 0x00} // 31 1 ,{0x42, 0x61, 0x51, 0x49, 0x46} // 32 2 ,{0x21, 0x41, 0x45, 0x4b, 0x31} // 33 3 ,{0x18, 0x14, 0x12, 0x7f, 0x10} // 34 4 ,{0x27, 0x45, 0x45, 0x45, 0x39} // 35 5 ,{0x3c, 0x4a, 0x49, 0x49, 0x30} // 36 6 ,{0x01, 0x71, 0x09, 0x05, 0x03} // 37 7 ,{0x36, 0x49, 0x49, 0x49, 0x36} // 38 8 ,{0x06, 0x49, 0x49, 0x29, 0x1e} // 39 9 ,{0x00, 0x36, 0x36, 0x00, 0x00} // 3a : ,{0x00, 0x56, 0x36, 0x00, 0x00} // 3b ; ,{0x08, 0x14, 0x22, 0x41, 0x00} // 3c < ,{0x14, 0x14, 0x14, 0x14, 0x14} // 3d = ,{0x00, 0x41, 0x22, 0x14, 0x08} // 3e > ,{0x02, 0x01, 0x51, 0x09, 0x06} // 3f ? ,{0x32, 0x49, 0x79, 0x41, 0x3e} // 40 @ ,{0x7e, 0x11, 0x11, 0x11, 0x7e} // 41 A ,{0x7f, 0x49, 0x49, 0x49, 0x36} // 42 B ,{0x3e, 0x41, 0x41, 0x41, 0x22} // 43 C ,{0x7f, 0x41, 0x41, 0x22, 0x1c} // 44 D ,{0x7f, 0x49, 0x49, 0x49, 0x41} // 45 E ,{0x7f, 0x09, 0x09, 0x09, 0x01} // 46 F ,{0x3e, 0x41, 0x49, 0x49, 0x7a} // 47 G ,{0x7f, 0x08, 0x08, 0x08, 0x7f} // 48 H ,{0x00, 0x41, 0x7f, 0x41, 0x00} // 49 I ,{0x20, 0x40, 0x41, 0x3f, 0x01} // 4a J ,{0x7f, 0x08, 0x14, 0x22, 0x41} // 4b K ,{0x7f, 0x40, 0x40, 0x40, 0x40} // 4c L ,{0x7f, 0x02, 0x0c, 0x02, 0x7f} // 4d M ,{0x7f, 0x04, 0x08, 0x10, 0x7f} // 4e N ,{0x3e, 0x41, 0x41, 0x41, 0x3e} // 4f O ,{0x7f, 0x09, 0x09, 0x09, 0x06} // 50 P ,{0x3e, 0x41, 0x51, 0x21, 0x5e} // 51 Q ,{0x7f, 0x09, 0x19, 0x29, 0x46} // 52 R ,{0x46, 0x49, 0x49, 0x49, 0x31} // 53 S ,{0x01, 0x01, 0x7f, 0x01, 0x01} // 54 T ,{0x3f, 0x40, 0x40, 0x40, 0x3f} // 55 U ,{0x1f, 0x20, 0x40, 0x20, 0x1f} // 56 V ,{0x3f, 0x40, 0x38, 0x40, 0x3f} // 57 W ,{0x63, 0x14, 0x08, 0x14, 0x63} // 58 X ,{0x07, 0x08, 0x70, 0x08, 0x07} // 59 Y ,{0x61, 0x51, 0x49, 0x45, 0x43} // 5a Z ,{0x00, 0x7f, 0x41, 0x41, 0x00} // 5b [ ,{0x02, 0x04, 0x08, 0x10, 0x20} // 5c ¥ ,{0x00, 0x41, 0x41, 0x7f, 0x00} // 5d ] ,{0x04, 0x02, 0x01, 0x02, 0x04} // 5e ^ ,{0x40, 0x40, 0x40, 0x40, 0x40} // 5f _ ,{0x00, 0x01, 0x02, 0x04, 0x00} // 60 ` ,{0x20, 0x54, 0x54, 0x54, 0x78} // 61 a ,{0x7f, 0x48, 0x44, 0x44, 0x38} // 62 b ,{0x38, 0x44, 0x44, 0x44, 0x20} // 63 c ,{0x38, 0x44, 0x44, 0x48, 0x7f} // 64 d ,{0x38, 0x54, 0x54, 0x54, 0x18} // 65 e ,{0x08, 0x7e, 0x09, 0x01, 0x02} // 66 f ,{0x0c, 0x52, 0x52, 0x52, 0x3e} // 67 g ,{0x7f, 0x08, 0x04, 0x04, 0x78} // 68 h ,{0x00, 0x44, 0x7d, 0x40, 0x00} // 69 i ,{0x20, 0x40, 0x44, 0x3d, 0x00} // 6a j ,{0x7f, 0x10, 0x28, 0x44, 0x00} // 6b k ,{0x00, 0x41, 0x7f, 0x40, 0x00} // 6c l ,{0x7c, 0x04, 0x18, 0x04, 0x78} // 6d m ,{0x7c, 0x08, 0x04, 0x04, 0x78} // 6e n ,{0x38, 0x44, 0x44, 0x44, 0x38} // 6f o ,{0x7c, 0x14, 0x14, 0x14, 0x08} // 70 p ,{0x08, 0x14, 0x14, 0x18, 0x7c} // 71 q ,{0x7c, 0x08, 0x04, 0x04, 0x08} // 72 r ,{0x48, 0x54, 0x54, 0x54, 0x20} // 73 s ,{0x04, 0x3f, 0x44, 0x40, 0x20} // 74 t ,{0x3c, 0x40, 0x40, 0x20, 0x7c} // 75 u ,{0x1c, 0x20, 0x40, 0x20, 0x1c} // 76 v ,{0x3c, 0x40, 0x30, 0x40, 0x3c} // 77 w ,{0x44, 0x28, 0x10, 0x28, 0x44} // 78 x ,{0x0c, 0x50, 0x50, 0x50, 0x3c} // 79 y ,{0x44, 0x64, 0x54, 0x4c, 0x44} // 7a z ,{0x00, 0x08, 0x36, 0x41, 0x00} // 7b { ,{0x00, 0x00, 0x7f, 0x00, 0x00} // 7c | ,{0x00, 0x41, 0x36, 0x08, 0x00} // 7d } ,{0x10, 0x08, 0x08, 0x10, 0x08} // 7e ← ,{0x78, 0x46, 0x41, 0x46, 0x78} // 7f → }; void delay(int ms){ while(ms){ _delay_ms(0.96); ms--; } } void adc_init(){ DDRC=0x00; PORTC=0x00; unsigned char channel = 0; ADMUX=(channel & 0x0f); // ADCSRA: ADC Control and Status Register // ADPS2..ADPS0: ADC frequency Prescaler Select Bits // ADEN: Analog Digital Converter Enable, set this before setting ADSC ADCSRA |= (1 << ADPS2) | (1 << ADPS1) | (1 << ADPS0); // Set ADC prescalar to 128 ADMUX |= (1 << REFS0); // Set ADC reference to AVCC // ADMUX |= (1 << ADLAR); // Left adjust ADC result to allow easy 8 bit reading ADCSRA |= (1 << ADEN); // Enable ADC // ADCSRA |= (1 << ADSC); // Start A2D Conversions } unsigned int adcread(short channel){ unsigned int ADresult; ADMUX = (ADMUX & (unsigned int) 0xf0) | (channel & (unsigned int) 0x0f); _delay_ms(10); ADCSRA |= (1 << ADSC); // Start A2D Conversions while (bit_is_set(ADCSRA, ADSC)); ADresult = ADCL; ADresult |= ((int)ADCH) << 8; return(ADresult); } void LcdCharacter(char character) { LcdWrite(LCD_D, 0x00); for (int index = 0; index < 5; index++) { LcdWrite(LCD_D, ASCII[character - 0x20][index]); } LcdWrite(LCD_D, 0x00); } void LcdClear(void) { for (int index = 0; index < LCD_X * LCD_Y / 8; index++) { LcdWrite(LCD_D, 0x00); } } void LcdString(char *characters) { while (*characters) { LcdCharacter(*characters++); } } void LcdWrite(byte dc, byte data) { int x; if (dc==LOW) cbi(PORTD,5); else sbi(PORTD,5); cbi(PORTD, 0); // shiftOut(PIN_SDIN, PIN_SCLK, MSBFIRST, data); for (x=7;x>=0;x--){ // MSB first if (((data>>x)&1)==0) cbi(PORTD,6); else sbi(PORTD,6); sbi(PORTD,7); // toggle pin 7 SCLK cbi(PORTD,7); } sbi(PORTD, 0); } void LcdInitialise(void) { DDRD=0xE3; // SCE as d0, RESET as d1, DC as d5, SDIN as d6, SCLK as d7 - all outs DDRC=0x0E;// TODO add pc1/2/3 as charge pump cbi(PORTD, 1); sbi(PORTD, 1); LcdWrite( LCD_CMD, 0x21 ); // LCD Extended Commands. LcdWrite( LCD_CMD, 0xBf ); // Set LCD Vop (Contrast). //B1 LcdWrite( LCD_CMD, 0x04 ); // Set Temp coefficent. //0x04 LcdWrite( LCD_CMD, 0x14 ); // LCD bias mode 1:48. //0x13 LcdWrite( LCD_CMD, 0x0C ); // LCD in normal mode. 0x0d for inverse LcdWrite(LCD_C, 0x20); LcdWrite(LCD_C, 0x0C); } int main(){ int x,y,z,adc,lenny=0,index,count=0; unsigned char mybuffer[16]; // init adc_init(); LcdInitialise(); LcdClear(); // pins for 2 bridges +- = PB0-PB3 DDRB=0x0F; /* port rest of soil testing - flip/sample/display */ while(1){ sbi(PORTB,1); cbi(PORTB,0); delay(36); // 137 hz x = adcread(0); cbi(PORTB,1); sbi(PORTB,0); delay(36); y = adcread(0); if (x>y) adc+=x-y; if (x32){ z=adc/32; for (index = 0; index < 504-(lenny*7); index++) { LcdWrite(LCD_D, 0x00); } lenny=sprintf(mybuffer,"xx: %d",x); LcdString(mybuffer); // LcdString("Hello World!"); adc=0; count=0; // pause also for one second delay(1000); } } } **LCD code from: http://www.arduino.cc/playground/Code/PCD8544**