多通道ECG心率监测系统

项目背景

整体方案

下位机设计

#include <compat/deprecated.h>
#include <FlexiTimer2.h>
//http://www.arduino.cc/playground/Main/FlexiTimer2

// All definitions
#define NUMCHANNELS 6
#define HEADERLEN 4
#define PACKETLEN (NUMCHANNELS * 2 + HEADERLEN + 1)
#define SAMPFREQ 256                      // ADC sampling rate 256
#define TIMER2VAL (1024/(SAMPFREQ))       // Set 256Hz sampling frequency                    
#define LED1  13
#define CAL_SIG 9

// Global constants and variables
volatile unsigned char TXBuf[PACKETLEN];  //The transmission packet
volatile unsigned char TXIndex;           //Next byte to write in the transmission packet.
volatile unsigned char CurrentCh;         //Current channel being sampled.
volatile unsigned char counter = 0;	  //Additional divider used to generate CAL_SIG
volatile unsigned int ADC_Value = 0;	  //ADC current value

//~~~~~~~~~~
// Functions
//~~~~~~~~~~

/****************************************************/
/*  Function name: Toggle_LED1                      */
/*  Parameters                                      */
/*    Input   :  No	                            */
/*    Output  :  No                                 */
/*    Action: Switches-over LED1.                   */
/****************************************************/
void Toggle_LED1(void){

 if((digitalRead(LED1))==HIGH){ digitalWrite(LED1,LOW); }
 else{ digitalWrite(LED1,HIGH); }
 
}


/****************************************************/
/*  Function name: toggle_GAL_SIG                   */
/*  Parameters                                      */
/*    Input   :  No	                            */
/*    Output  :  No                                 */
/*    Action: Switches-over GAL_SIG.                */
/****************************************************/
void toggle_GAL_SIG(void){
  
 if(digitalRead(CAL_SIG) == HIGH){ digitalWrite(CAL_SIG, LOW); }
 else{ digitalWrite(CAL_SIG, HIGH); }
 
}


/****************************************************/
/*  Function name: setup                            */
/*  Parameters                                      */
/*    Input   :  No	                            */
/*    Output  :  No                                 */
/*    Action: Initializes all peripherals           */
/****************************************************/
void setup() {

 noInterrupts();  // Disable all interrupts before initialization
 
 // LED1
 pinMode(LED1, OUTPUT);  //Setup LED1 direction
 digitalWrite(LED1,LOW); //Setup LED1 state
 pinMode(CAL_SIG, OUTPUT);
 
 //Write packet header and footer
 TXBuf[0] = 0xa5;    //Sync 0
 TXBuf[1] = 0x5a;    //Sync 1
 TXBuf[2] = 2;       //Protocol version
 TXBuf[3] = 0;       //Packet counter
 TXBuf[4] = 0x02;    //CH1 High Byte
 TXBuf[5] = 0x00;    //CH1 Low Byte
 TXBuf[6] = 0x02;    //CH2 High Byte
 TXBuf[7] = 0x00;    //CH2 Low Byte
 TXBuf[8] = 0x02;    //CH3 High Byte
 TXBuf[9] = 0x00;    //CH3 Low Byte
 TXBuf[10] = 0x02;   //CH4 High Byte
 TXBuf[11] = 0x00;   //CH4 Low Byte
 TXBuf[12] = 0x02;   //CH5 High Byte
 TXBuf[13] = 0x00;   //CH5 Low Byte
 TXBuf[14] = 0x02;   //CH6 High Byte
 TXBuf[15] = 0x00;   //CH6 Low Byte 
 TXBuf[2 * NUMCHANNELS + HEADERLEN] =  0x01;	// Switches state

 // Timer2
 // Timer2 is used to setup the analag channels sampling frequency and packet update.
 // Whenever interrupt occures, the current read packet is sent to the PC
 // In addition the CAL_SIG is generated as well, so Timer1 is not required in this case!
 FlexiTimer2::set(TIMER2VAL, Timer2_Overflow_ISR);
 FlexiTimer2::start();
 
 // Serial Port
 Serial.begin(57600);
 //Set speed to 57600 bps
 
 // MCU sleep mode = idle.
 //outb(MCUCR,(inp(MCUCR) | (1<<SE)) & (~(1<<SM0) | ~(1<<SM1) | ~(1<<SM2)));
 
 interrupts();  // Enable all interrupts after initialization has been completed
}

/****************************************************/
/*  Function name: Timer2_Overflow_ISR              */
/*  Parameters                                      */
/*    Input   :  No	                            */
/*    Output  :  No                                 */
/*    Action: Determines ADC sampling frequency.    */
/****************************************************/
void Timer2_Overflow_ISR()
{
  // Toggle LED1 with ADC sampling frequency /2
  Toggle_LED1();
  
  //Read the 6 ADC inputs and store current values in Packet
  for(CurrentCh=0;CurrentCh<6;CurrentCh++){
    ADC_Value = analogRead(CurrentCh);
    TXBuf[((2*CurrentCh) + HEADERLEN)] = ((unsigned char)((ADC_Value & 0xFF00) >> 8));	// Write High Byte
    TXBuf[((2*CurrentCh) + HEADERLEN + 1)] = ((unsigned char)(ADC_Value & 0x00FF));	// Write Low Byte
  }
	 
  // Send Packet
  for(TXIndex=0;TXIndex<17;TXIndex++){
    Serial.write(TXBuf[TXIndex]);
  }
  
  // Increment the packet counter
  TXBuf[3]++;			
  
  // Generate the CAL_SIGnal
  counter++;		// increment the devider counter
  if(counter == 12){	// 250/12/2 = 10.4Hz ->Toggle frequency
    counter = 0;
    toggle_GAL_SIG();	// Generate CAL signal with frequ ~10Hz
  }
}


/****************************************************/
/*  Function name: loop                             */
/*  Parameters                                      */
/*    Input   :  No	                            */
/*    Output  :  No                                 */
/*    Action: Puts MCU into sleep mode.             */
/****************************************************/
void loop() {
  
 __asm__ __volatile__ ("sleep");
 
}`

上位机设计

总结