MIKROE-2376

Page 1 of 3 C Meter click From MikroElektonika Documentation C Meter click C Meter click has circuitry for measuring the value of capacitors. The design is based on a NE-555 timer/square-wave generator. The chip is implemented in an astable multivibrator circuit with fixed resistors and adjustable capacitors. Features and usage notes C Meter click has four different-sized plates for placing SMD capacitors (covering standard SMD packaging dimensions) as well as a socket for inserting a thru hole resistor. Each plate is labeled with package size in standard imperial measurements: 1210 — 3.2mm x 2.5mm 1206 — 3.2 mm x 1.6 mm 0805 — 2.0 mm x x1.25 mm Schematic also available in PDF (http://cdndocs.mikroe.com/images/d/dd/C_Meter_click_schem 0603 — 1.6 mm x 0.8 mm The board outputs a square wave frequency through the INT pin. Depending on the capacitor placed on the board, the value of this frequency changes. The value of a capacitor can be inferred using a simple algorithm (shown in the Libstock code example). Onboard screw terminals are placed to allow the click to be used with oscillator probes. C Meter click is designed to use a 5V power supply, but can work with either 3.3V or 5V logic levels. C Meter click IC/Module NE-555 precision timer (http://www.ti.com/lit/ds/symlink/ne555.pdf) Interface INT, RST Power 5V (possible to use with 3.3V I/O) supply Website Programming This code snippet uses a preset calibration value and finds the capacitance of the capacitor for displaying on the TFT. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 #include #include #include "resources.h" // C_Meter Click sbit C_METER_RST at GPIOC_ODR.B2; sbit C_METER_INT at GPIOD_ODR.B10; // TFT module connections unsigned int TFT_DataPort at GPIOE_ODR; sbit TFT_RST at GPIOE_ODR.B8; sbit TFT_RS at GPIOE_ODR.B12; sbit TFT_CS at GPIOE_ODR.B15; sbit TFT_RD at GPIOE_ODR.B10; sbit TFT_WR at GPIOE_ODR.B11; sbit TFT_BLED at GPIOE_ODR.B9; void void void void system_setup( void ); setup_interrupt( void ); InitTimer2( void ); display_init( void ); uint32_t int_count = 0; uint32_t timer_count_end = 0; bool sec_flag = false; void main() { //Local Declarations char uart_text[ 40 ]; float c_cal = 0.0; float t_meas = 0.0; float c_meas = 0.0; float final = 0.0; float t_cal = 0.0; system_setup(); setup_interrupt(); InitTimer2(); display_init(); t_cal = 1.0 / 23350.0; www.mikroe.com/click/c-meter (http://www.mikroe.com/click/c-meter) Page 2 of 3 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 c_cal = t_cal / 77616.0; int_count = 0; while(1) { } if( sec_flag ) { //Measurment t_meas = 1.0 / timer_count_end; c_meas = t_meas / 77616.0; final = fabs( c_cal - c_meas ); //Print out FloatToStr( final, final_text ); TFT_Rectangle( 100, 100, 200, 120 ); TFT_Write_Text( final_text, 100, 100 ); TFT_Write_Text( " Farad", 190, 100 ); //Reset flags sec_flag = false; int_count = 0; timer_count_end = 0; } } void display_init( void ) { TFT_Init_ILI9341_8bit( 320, 240 ); TFT_BLED = 1; TFT_Set_Pen( CL_WHITE, 1 ); TFT_Set_Brush( 1, CL_WHITE, 0, 0, 0, 0 ); TFT_Set_Font( TFT_defaultFont, CL_BLACK, FO_HORIZONTAL ); TFT_Fill_Screen( CL_WHITE ); TFT_Set_Pen( CL_BLACK, 1 ); TFT_Line( 20, 46, 300, 46 ); TFT_Line( 20, 70, 300, 70 ); TFT_Line( 20, 220, 300, 220 ); TFT_Set_Pen( CL_WHITE, 1 ); TFT_Set_Font( &HandelGothic_BT21x22_Regular, CL_RED, FO_HORIZONTAL ); TFT_Write_Text( "C Meter click", 105, 14 ); TFT_Set_Font( &Tahoma15x16_Bold, CL_BLUE, FO_HORIZONTAL ); TFT_Write_Text( "C Meter", 135, 50 ); TFT_Set_Font( &Verdana12x13_Regular, CL_BLACK, FO_HORIZONTAL ); TFT_Write_Text( "EasyMx PRO v7 for STM32", 19, 223 ); TFT_Set_Font( &Verdana12x13_Regular, CL_RED, FO_HORIZONTAL ); TFT_Write_Text( "www.mikroe.com", 200, 223 ); TFT_Set_Font( &Tahoma15x16_Bold, CL_BLACK, FO_HORIZONTAL ); } void system_setup( void ) { //GPIO GPIO_Digital_Output( &GPIOC_BASE, _GPIO_PINMASK_2 ); GPIO_Digital_Input( &GPIOD_BASE, _GPIO_PINMASK_10 ); //RST //INT //RST Toggle C_METER_RST = 0; Delay_ms(50); C_METER_RST = 1; //UART UART1_Init( 9600 ); UART1_Write_Text( "UART Initialized\r\n" ); } void setup_interrupt( void ) { GPIO_Digital_Output(&GPIOE_BASE, _GPIO_PINMASK_HIGH); GPIOE_ODR = 0xAAAA; GPIO_Digital_Input(&GPIOD_BASE, _GPIO_PINMASK_10); } RCC_APB2ENR.AFIOEN = 1; AFIO_EXTICR3 = 0x0300; EXTI_FTSR = 0x00000400; EXTI_IMR |= 0x00000400; NVIC_IntEnable(IVT_INT_EXTI15_10); EnableInterrupts(); // // // // // // // Enable digital output on PORTD Enable clock for alternate pin functions PD10 as External interrupt Set interrupt on Rising edge Set mask Enable External interrupt Enables the processor interrupt. void ExtInt() iv IVT_INT_EXTI15_10 ics ICS_AUTO { EXTI_PR.B10 = 1; // clear flag int_count++; } void InitTimer2() //1 second { RCC_APB1ENR.TIM2EN = 1; TIM2_CR1.CEN = 0; TIM2_PSC = 1124; TIM2_ARR = 63999; NVIC_IntEnable(IVT_INT_TIM2); TIM2_DIER.UIE = 1; TIM2_CR1.CEN = 1; } void Timer2_interrupt() iv IVT_INT_TIM2 { TIM2_SR.UIF = 0; timer_count_end = int_count; int_count = 0; sec_flag = true; } Code examples that demonstrate the usage of C Meter click with MikroElektronika hardware, written for mikroC for ARM is available on Libstock (http://libstock.mikroe.com/projects/view/1879/c-meter-click). Resources Page 3 of 3 - C Meter click example on Libstock (http://libstock.mikroe.com/projects/view/1879/c-meter-click) - NE-555 vendor's data sheet (http://www.ti.com/lit/ds/symlink/ne555.pdf) - mikroBUS standard specifications (http://download.mikroe.com/documents/standards/mikrobus/mikrobus-standard-specification-v200.pdf) Retrieved from "http://docs.mikroe.com/index.php?title=C_Meter_click&oldid=601" ◾ This page was last modified on 1 August 2016, at 17:04. ◾ Content is available under Creative Commons Attribution unless otherwise noted. http://docs.mikroe.com/index.php?title=C_Meter_click&printable=yes 8/8/2016