EMG Click

How does it work?

EMG Click is based on two MCP609s, micropower CMOS operational amplifiers from Microchip. These are unity-gain stable Op Amps with a low offset voltage, including rail-to-rail output swing capability and a low input bias current. The MAX6106, a low-cost micropower, low-dropout, high-output-current voltage reference from Analog Devices, provides the reference voltage. You can choose a reference voltage between 2.048 and 4.96V over the ADC REF jumper, where the lower is set by default. When you connect all three electrodes to each other, the output should be constant voltage. There is also a trimmer potentiometer that adjusts the gain. The jumper and trimmer potentiometer are used to make the output voltage level from EMG Click accommodate the input voltage level of ADC, which will be used.

Electromyography, or EMG, is a diagnostic technique for measuring the electrical activity of muscles. It is often used to diagnose the health of these muscles and the neurons that control them. These neurons are called motor neurons. They transmit electrical signals, and the muscles contract when this happens. An EMG Click collects these signals and translates them into a graphical representation. The electrodes are connected to the board with a cable that plugs into the onboard 3.5mm phone jack. For optimal results, place the first DRL electrode on the wrist of the hand. Place the second and third electrodes on the muscle you want to measure.

EKG Click provides ESD protection, overvoltage protection, and overcurrent protection, where the input block acts as a filter that prevents radio waves from entering the preamplifier. After it passes the preamplifier, high-pass filter, and amplifier, the signal goes again through the high-pass filter and then the low-pass filter until it can be read from the host MCU over an analog AN pinmikroBUS™ socket.

EMG Click also consists of the DRL circuit (driven right leg), an electronic circuit often added to biological signal amplifiers to reduce common-mode interference. Biological signal amplifiers such as EMG circuits measure very small electrical signals emitted by the body, often as small as several microvolts. As the patient’s body acts as an antenna, the DRL eliminates interference noise by actively canceling it.

This Click board™ can be operated only with a 5V logic voltage level. The board must perform appropriate logic voltage level conversion before using MCUs with different logic levels. However, the Click board™ comes equipped with a library containing functions and an example code that can be used as a reference for further development.

Specifications

Pinout diagram

This table shows how the pinout on EMG Click corresponds to the pinout on the mikroBUS™ socket (the latter shown in the two middle columns).

Notes	Pin					Pin	Notes
Analog Output	AN	1	AN	PWM	16	NC
	NC	2	RST	INT	15	NC
	NC	3	CS	RX	14	NC
	NC	4	SCK	TX	13	NC
	NC	5	MISO	SCL	12	NC
	NC	6	MOSI	SDA	11	NC
	NC	7	3.3V	5V	10	5V	Power Supply
Ground	GND	8	GND	GND	9	GND	Ground

Onboard settings and indicators

EMG Click electrical specifications

Software Support

We provide a library for the EMG Click as well as a demo application (example), developed using MIKROE compilers. The demo can run on all the main MIKROE development boards.

Package can be downloaded/installed directly from NECTO Studio Package Manager(recommended), downloaded from our LibStock™ or found on Mikroe github account.

Library Description

This library contains API for EMG Click driver.

Key functions

• emg_read_an_pin_value EMG read AN pin value function.

• emg_read_an_pin_voltage EMG read AN pin voltage level function.

Example Description

This is an example which demonstrates the use of EMG Click board.

 void application_task ( void )  { 
     uint16_t emg_an = 0; 
     if ( emg_read_an_pin_value( &emg, &emg_an ) == ADC_SUCCESS ){ 
         log_printf( &logger, " %u,%lurn ", emg_an, time ); 
     } 
     time += 5; 
     Delay_ms ( 5 ); 
 }

The full application code, and ready to use projects can be installed directly from NECTO Studio Package Manager(recommended), downloaded from our LibStock™ or found on Mikroe github account.

Other Mikroe Libraries used in the example:

• MikroSDK.Board
• MikroSDK.Log
• Click.EMG

Additional notes and informations

Depending on the development board you are using, you may need USB UART click, USB UART 2 Click or RS232 Click to connect to your PC, for development systems with no UART to USB interface available on the board. UART terminal is available in all MIKROE compilers.

mikroSDK

This Click board™ is supported with mikroSDK - MIKROE Software Development Kit. To ensure proper operation of mikroSDK compliant Click board™ demo applications, mikroSDK should be downloaded from the LibStock and installed for the compiler you are using.

For more information about mikroSDK, visit the official page.