Diff: main.cpp

Revision:

3:420d5efbd967

Parent:

2:812d40f1853d

Child:

4:828118be72d0

--- a/main.cpp	Fri Aug 18 17:37:07 2017 +0000
+++ b/main.cpp	Tue Aug 22 21:40:49 2017 +0000
@@ -15,7 +15,10 @@
 }  
 
 int main()
-{
+{   
+    const int RTOR_STATUS_MASK = ( 1<<10 );
+    const int EINT_STATUS_MASK = ( 1<<23 );
+    
     Serial pc(USBTX, USBRX);            // Use USB debug probe for serial link
     pc.baud(115200);                    // Baud rate = 115200
     
@@ -29,7 +32,7 @@
     SPI spiBus(SPI2_MOSI, SPI2_MISO, SPI2_SCK);     // SPI bus, P5_1 = MOSI, 
                                                     // P5_2 = MISO, P5_0 = SCK
     
-    MAX30003 *ecgAFE;
+    MAX30003 * ecgAFE;
     ecgAFE = new MAX30003(spiBus, P5_3);    // New MAX30003 on spiBus, CS = P5_3 
     ecg_config(*ecgAFE);                    // Config ECG 
      
@@ -42,39 +45,49 @@
     
     while(1) {
         
-        bLed = LED_ON;
-        
         /* Read back ECG samples from the FIFO */
         if( ecgFIFOIntFlag ) {
             pc.printf("Interrupt received....\r\n");
-            bLed = LED_OFF;
-                     // Clear interrupt flag
+            status = ecgAFE->readRegister( MAX30003::STATUS );      // Read the STATUS register
+            pc.printf("Status : 0x%x\r\n"
+                      "Current BPM is %3.2f\r\n\r\n", status, BPM);
             
-            status = ecgAFE->readRegister( MAX30003::STATUS );
-            pc.printf("Status : 0x%x\r\nCurrent BPM is %f\r\n\r\n", status, BPM);
+            // Check if R-to-R interrupt asserted
+            if( ( status & RTOR_STATUS_MASK ) == RTOR_STATUS_MASK ){              // Check if RtoR update
             
-            
-            if( ( status & (1<<10) ) == (1<<10) ){
                 ecgFIFOIntFlag = 0;
                 pc.printf("R-to-R Interrupt \r\n");
-                RtoR = ecgAFE->readRegister( MAX30003::RTOR );
-                BPM = 60.0*RtoR/32768.0;
-                pc.printf("RtoR : %d\r\n\r\n", RtoR);
+                RtoR = ecgAFE->readRegister( MAX30003::RTOR );  // Read RtoR register
+                BPM = 60.0*RtoR/32768.0;                        // Convert to BPM
+                pc.printf("RtoR : %d\r\n\r\n", RtoR);           // Print BPM/RtoR
+                
             } 
              
-            if ( ( status & (1<<23) ) == (1<<23) ) {
-                ecgFIFOIntFlag = 0;
+            // Check if EINT interrupt asserted
+            if ( ( status & EINT_STATUS_MASK ) == EINT_STATUS_MASK ) {     
+            
+                ecgFIFOIntFlag = 0; 
                 pc.printf("FIFO Interrupt \r\n");
-                readSamples = 0;            // Reset sample counter
+                readSamples = 0;                        // Reset sample counter
+                
                 do {
                     ecgFIFO = ecgAFE->readRegister( MAX30003::ECG_FIFO );   // Read FIFO
                     ecgSample[readSamples] = ecgFIFO >> 8;                  // Isolate voltage data
                     ETAG[readSamples] = ( ecgFIFO >> 3 ) & 0b111;           // Isolate ETAG
                     readSamples++;                                          // Increment sample counter
-                } while ( ETAG[readSamples-1] == 0x0 || ETAG[readSamples-1] == 0x1 );   // Check that sample is valid
+                
+                // Check that sample is not last sample in FIFO                                              
+                } while ( ETAG[readSamples-1] == 0x0 || 
+                          ETAG[readSamples-1] == 0x1 ); 
             
                 pc.printf("%d samples read from FIFO \r\n", readSamples);
                 
+                // Check if FIFO has overflowed
+                if( ETAG[readECGSamples - 1] == 0x7 ){                  
+                    ecgAFE.writeRegister( MAX30003::FIFO_RST , 0); // Reset FIFO
+                }
+                
+                /* Print results */
                 for( idx = 0; idx < readSamples; idx++ ) {
                     pc.printf("Sample : %6d, \tETAG : 0x%x\r\n", ecgSample[idx], ETAG[idx]);           
                 }
@@ -92,62 +105,54 @@
 
     // Reset ECG to clear registers
     ecgAFE.writeRegister( MAX30003::SW_RST , 0);
-        
-    
     
     // General config register setting
     MAX30003::GeneralConfiguration_u CNFG_GEN_r;
-    CNFG_GEN_r.bits.en_ecg = 1;
-    CNFG_GEN_r.bits.rbiasn = 1;
-    CNFG_GEN_r.bits.rbiasp = 1;
-    CNFG_GEN_r.bits.en_rbias = 1;
-    CNFG_GEN_r.bits.imag = 2;
-    CNFG_GEN_r.bits.en_dcloff = 1;    
+    CNFG_GEN_r.bits.en_ecg = 1;     // Enable ECG channel
+    CNFG_GEN_r.bits.rbiasn = 1;     // Enable resistive bias on negative input
+    CNFG_GEN_r.bits.rbiasp = 1;     // Enable resistive bias on positive input
+    CNFG_GEN_r.bits.en_rbias = 1;   // Enable resistive bias
+    CNFG_GEN_r.bits.imag = 2;       // Current magnitude = 10nA
+    CNFG_GEN_r.bits.en_dcloff = 1;  // Enable DC lead-off detection   
     ecgAFE.writeRegister( MAX30003::CNFG_GEN , CNFG_GEN_r.all);
         
     
     // ECG Config register setting
     MAX30003::ECGConfiguration_u CNFG_ECG_r;
-    CNFG_ECG_r.bits.dlpf = 1;
-    CNFG_ECG_r.bits.dhpf = 1;
-    CNFG_ECG_r.bits.gain = 3; 
-    CNFG_ECG_r.bits.rate = 3;  
+    CNFG_ECG_r.bits.dlpf = 1;       // Digital LPF cutoff = 40Hz
+    CNFG_ECG_r.bits.dhpf = 1;       // Digital HPF cutoff = 0.5Hz
+    CNFG_ECG_r.bits.gain = 3;       // ECG gain = 160V/V
+    CNFG_ECG_r.bits.rate = 2;       // Sample rate = 128 sps
     ecgAFE.writeRegister( MAX30003::CNFG_ECG , CNFG_ECG_r.all);
       
     
     //R-to-R configuration
     MAX30003::RtoR1Configuration_u CNFG_RTOR_r;
-    CNFG_RTOR_r.bits.en_rtor = 1;    
+    CNFG_RTOR_r.bits.en_rtor = 1;           // Enable R-to-R detection
     ecgAFE.writeRegister( MAX30003::CNFG_RTOR1 , CNFG_RTOR_r.all);
        
         
     //Manage interrupts register setting
     MAX30003::ManageInterrupts_u MNG_INT_r;
-    MNG_INT_r.bits.efit = 0b00011;   
-    MNG_INT_r.bits.clr_rrint = 0b01;
+    MNG_INT_r.bits.efit = 0b00011;          // Assert EINT w/ 4 unread samples
+    MNG_INT_r.bits.clr_rrint = 0b01;        // Clear R-to-R on RTOR reg. read back
     ecgAFE.writeRegister( MAX30003::MNGR_INT , MNG_INT_r.all);
     
     
     //Enable interrupts register setting
     MAX30003::EnableInterrupts_u EN_INT_r;
-    EN_INT_r.all = 0;
-    EN_INT_r.bits.en_eint = 1;
-    EN_INT_r.bits.en_rrint = 1;
-    EN_INT_r.bits.intb_type = 0b11;
+    EN_INT_r.bits.en_eint = 1;              // Enable EINT interrupt
+    EN_INT_r.bits.en_rrint = 1;             // Enable R-to-R interrupt
+    EN_INT_r.bits.intb_type = 3;            // Open-drain NMOS with internal pullup
     ecgAFE.writeRegister( MAX30003::EN_INT , EN_INT_r.all);
        
        
     //Dyanmic modes config
     MAX30003::ManageDynamicModes_u MNG_DYN_r;
-    MNG_DYN_r.bits.fast = 0;    
+    MNG_DYN_r.bits.fast = 0;                // Fast recovery mode disabled
     ecgAFE.writeRegister( MAX30003::MNGR_DYN , MNG_DYN_r.all);
        
     
-    //MUX Config
-    MAX30003::MuxConfiguration_u CNFG_MUX_r;
-    CNFG_MUX_r.bits.pol = 0;    
-    ecgAFE.writeRegister( MAX30003::CNFG_EMUX , CNFG_MUX_r.all);
-    
     return;
 }