fixed bugs in sample rate command

src/main.cpp

@@ -9,20 +9,22 @@ using namespace helpers;               // contains the verbose levels from Instr
 #include <BufferSupport.h> //data buffers
 // #include <SerialSupport.h>  //Serial object
 
-const float versionNumber = 1.1;    // version displayed on boot
+const float versionNumber = 1.2;    // version displayed on boot
+bool outputFloat = false;          // true = ADC converted to float, false = ADC in 16 bit integer
 const uint16_t serialTimeOut = 1000; // timeout in ms
 const long serialBaudrate = 115200;
 const byte numChars = 32; //maximum length of messages parsed on receive.
 static uint16_t logFreqSamples = 200; // give samplecounter and summary every n samples
 uint8_t downSampler = 16;        // average n number of samples before storing. 1 = no downsampling, 2 = average two samples
-const uint8_t maxDownSampler = 128;    // max number of samples to average
-const uint16_t minSampleRate = 10; // Lowest Acceptable Sample Rate
-const uint16_t maxSampleRate = 8096; // Highest Acceptable Sample Rate
+const uint8_t maxDownSampler = 200;    // max number of samples to average
+const uint16_t minSampleRate = 1; // Lowest Acceptable Sample Rate (Hz)
+const uint32_t maxSampleRate = 100000; // Highest Acceptable Sample Rate (Hz)
 
 const uint8_t channelCountSize = 1;                          // always fixed at 1 byte
 const unsigned char channelCount[channelCountSize] = {0x01}; // number of active channels send to the plot, for now this is ADC. Should be 0x02 if Batt is also send.
 
 const int spiClockDivider = 42;  // ADC SPI speed
+SPISettings spiSettingsA(4000000, MSBFIRST, SPI_MODE1);
 const int chipSelectADCPin = 10; // ADC SPI
 const u_int8_t MOSIpin = 11;     // ADC SPI //not used, only one way communication
 const u_int8_t MISOpin = 12;     // ADC SPI
@@ -191,15 +193,22 @@ void aquisitionTask_Callback()
   // low. The data bits are then clocked, MSB first, by subsequent DCLOCK falling edges. The data is valid on both DCLOCK
   // edges. Although the rising edge can be used to capture the data, a digital host also using the DCLOCK falling edge allows a
   // faster reading rate, provided it has an acceptable hold time.
+  SPI.beginTransaction(spiSettingsA);
   digitalWrite(chipSelectADCPin, LOW);   // select the chip
+  //delayMicroseconds(2);
   byte adcByteHigh = SPI.transfer(0x00); // transfer 0x00 to the device, store byte received in adcByteHigh
-  adcByteHigh &= 0b00000011;             // corrects for 18 bit
+  //delayMicroseconds(2);
   byte adcByteMid = SPI.transfer(0x00);  // transfer 0x00 to the device, store byte received in adcByteMid
+  //delayMicroseconds(2);
   byte adcByteLow = SPI.transfer(0x00);  // transfer 0x00 to the device, store byte received in adcByteLow
+  //delayMicroseconds(2);
   digitalWrite(chipSelectADCPin, HIGH);  // deselect the chip
+  SPI.endTransaction();
 
   // combine the two parts into one 18-bit number:
-  ADCresult = ((adcByteHigh << 14) | (adcByteMid << 6) | (adcByteLow >> 2));
+  //ADCresult = ((adcByteHigh << 14) | (adcByteMid << 6) | (adcByteLow >> 2));
+  //ADCresult = ((adcByteHigh << 16) | (adcByteMid << 8) | (adcByteLow >>0));
+  ADCresult = (adcByteHigh & 3) << 14 | adcByteMid << 6 | adcByteLow >> 2; // & 3 part masks the two highest bits of adcByteHigh which should be 0 anyways.
   ADCresultArray[downSampleCounter] = ADCresult;
   
   //downSampler = 4 gives: 0 1 2 3
@@ -226,7 +235,7 @@ void aquisitionTask_Callback()
 
 
 
-// convert current time to bytes  (32 bit)  //TODO: this is unsigned, uScope expects singed int for time (why!?)
+    // convert current time to bytes  (32 bit)  //TODO: this is unsigned, uScope expects singed int for time (why!?)
     bufferMillis.buffer[3] = (uint8_t)(currentTime) & 0x80; // LSB   //0x80 instead of 0xFF seems to fix the negative time in uScope
     bufferMillis.buffer[2] = (uint8_t)(currentTime >> 8) & 0xFF;
     bufferMillis.buffer[1] = (uint8_t)(currentTime >> 16) & 0xFF;
@@ -242,14 +251,26 @@ void aquisitionTask_Callback()
 
     //average the ADC readings according to downsample amount
     ADCresult = 0; //clear ADCresult, which is also used above
+
+    //calculate average of the ADC readings
+    
     for (int i = 0; i < downSampler; i++)
     {
-    ADCresult = ADCresult + ADCresultArray[i];
+    ADCresult += ADCresultArray[i];
     }
-
+    ADCresult = ADCresult / downSampler; //compensate for downsampling
+    
+    
+    if(outputFloat){
     // convert to float voltage
-    ADCvolts = (5.0 * ((float)ADCresult / 65535)) / downSampler ; //convert to float and compensate for downsample
-    ADCvolts = ADCvolts - 2.5; //offset to compensate for the single supply ADC
+      ADCvolts = (5.0 * ((float)ADCresult / 65535)) ; //convert to volts and convert tp float
+      ADCvolts = ADCvolts - 2.5; //offset to compensate for the single supply ADC
+    }
+    else
+    {
+       ADCvolts = (float)ADCresult ; //cast to float without conversion into volts
+    }
+
     // convert to bytes
     byte *bADCvolts = (byte *)&ADCvolts;
 
@@ -367,7 +388,7 @@ void communicationTask_Callback()
         helpers::printToLog("Stop command received: disabled aquisitionTask (stop sampling).", verboseLevels::info);
       }
     }
-    else if (strncmp(receivedChars, "SetSampleRate", 13) == 0) // command starting with "SetSampleRate", should always be followed by 4 integers, for example "SetSampleRate1000" for 1000 Hz
+    else if (strncmp(receivedChars, "SetSampleRate", 13) == 0) // command starting with "SetSampleRate", should always be followed by 5 integers, for example "SetSampleRate01000" for 1000 Hz
     {
       if (aquisitionTask.isEnabled())
       {
@@ -375,9 +396,9 @@ void communicationTask_Callback()
       }
       else
       {
-          char argument[5];                        // stores the value received from the host in ASCCI text
-          memcpy(argument, &receivedChars[13], 4); // copy characters from full input command 
-          argument[4] = '\0';                      // termination character
+          char argument[6];                        // stores the value received from the host in ASCCI text
+          memcpy(argument, &receivedChars[13], 5); // copy characters from full input command 
+          argument[5] = '\0';                      // termination character
           int newSampleRate = atoi(argument);
           helpers::printToLog("Received SetSampleRate Command: " + String(newSampleRate), verboseLevels::info);
           
@@ -391,7 +412,7 @@ void communicationTask_Callback()
           }
           else
           {     
-            aquisitionTaskDuration = 1000000 / newSampleRate;   // µs per cycle   //for aquisition of sensor data
+            aquisitionTaskDuration = round(1000000 / newSampleRate);   // µs per cycle   //for aquisition of sensor data
             aquisitionTask.setInterval(aquisitionTaskDuration);
           }
       }