MIKROE-2436

Voltmeter click Voltmeter click is a mikroBUS™ add-on board for measuring voltage in an external electric circuit. The board is designed to measure Direct Current only, and has a measurement range from 0 to 24V (it’s possible to measure both positive and negative charges). The design of the board is based on an OpAmp set up as a differential amplifier with a buffered input. Two onboard screw terminals (probe+ and probe-) are bringing in the current, which then flows through a row of four resistors. A voltage – proportional to the input charge – is generated across the last two resistors. From there it is sent to the differential amplifier that further intensifies the difference between the two inputs (+/-). The resulting charge is exactly 33 times lower than the actual measured voltage. It is converted by an onboard 12-bit ADC before being outputted through the mikroBUS™ SPI interface (the firmware in the target board MCU should be set up to multiply the ADC value to get the actual voltage). It is also possible to output the analog value directly through the mikroBUS™ AN pin (useful if the target MCU has a higher resolution ADC). The board can work with either a 3.3V or a 5V power supply. Technical Specifications Applications Measuring DC Voltage from external circuit Key features Measurement range: 0-24Vdc 12-bit ADC SPI interface (+ AN pin) 3.3V or 5V power supply Key Benefits Measures both positive and negative charges Possible to measure analog values directly Works in all mikroC compilers Ready-to-use examples save development time mikroBUS™ is specially designed pinout standard with SPI, I2C, Analog, UART, Interrupt, PWM, Reset and Power  supply pins. See Standard Specification. Programming The following code snippet shows how to send temperature readings from Voltmeter click to a TFT display. . 1 void system_setup( void ); 2 unsigned int getADC( void ); 3 4 void main() 5{ 6 system_setup(); 7 8 while (1) 9 { 10 11 voltage = 0; 12 13 measurement = getADC() / 2; // Get ADC result 14 voltage = (measurement - calibration) * 33.3405; 15 16 FloatToStr(voltage, txt); 17 18 UART1_Write_Text(txt); 19 UART1_Write(32); 20 UART1_Write_Text("mV"); 21 UART1_Write(13); 22 UART1_Write(10); 23 24 delay_ms(1000); 25 } 26 } 27 28 void system_setup( void ) 29 { 30 GPIO_Digital_Output( &GPIOD_BASE, _GPIO_PINMASK_13 ); 31 32 UART1_Init(9600); // Initialize UART module at 9600 bps 33 Delay_ms(300); // Wait for UART module to stabilize 34 UART1_Write_Text( "UART Initialized\r\n" ); 35 36 voltage = 0; 37 sum = 0; 38 measurement = 0; 39 calibration = 0; 40 41 Chip_Select = 1; 42 43 // SPI 44 SPI3_Init_Advanced( _SPI_FPCLK_DIV16, _SPI_MASTER | _SPI_8_BIT | 45 _SPI_CLK_IDLE_LOW | _SPI_SECOND_CLK_EDGE_TRANSITION | 46 _SPI_MSB_FIRST | _SPI_SS_DISABLE | _SPI_SSM_ENABLE | 47 _SPI_SSI_1, &_GPIO_MODULE_SPI3_PC10_11_12 ); 48 Delay_ms(300); 49 UART1_Write_Text( "SPI Initialized\r\n" ); 50 51 calibration = getADC() / 2; 52 } Code examples that demonstrate the usage of Voltmeter click with MikroElektronika hardware, written for  mikroC for ARM, AVR, dsPIC, FT90x, PIC and PIC32 are available on Libstock. MIKROE-2436 Voltmeter click Copyright © 1998 - 2016. MikroElektronika d.o.o.