Diff: HPM/hpm.cpp

Revision:

2:680fc2690d10

Child:

3:2ab969b31f6b

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/HPM/hpm.cpp	Fri Sep 07 02:54:05 2018 +0000
@@ -0,0 +1,205 @@
+#include "mbed.h"
+#include "hpm.h"
+
+    
+HPM::HPM(Serial* device, Serial* debug): _device(device), _debug(debug)
+{
+   _device->baud(9600);
+   wait(0.1);
+}
+
+bool HPM::init(void)
+{
+    // Stop autosend
+    if (!this->stop_autosend())
+    {
+        _debug->printf("Stop autosend failed\r\n");
+        return 0;
+    }
+    
+    // Start fan
+    if (!this->start_measurement())
+    {
+        _debug->printf("Start measurement failed\r\n");
+        return 0;
+    }
+    
+    return 1;
+}
+    
+bool HPM::start_measurement(void)
+{
+    // First, we send the command
+    unsigned char start_measurement[] = {0x68, 0x01, 0x01, 0x96 };
+    for (int i=0; i<sizeof(start_measurement); i++)
+    {
+        _device->putc(start_measurement[i]);  
+    }
+  
+  //Then we wait for the response
+  while (!_device->readable()) {} // wait until chars arrive
+  char read1 = _device->getc();
+  char read2 = _device->getc();
+  
+  // Test the response
+  if ((read1 == 0xA5) && (read2 == 0xA5)){
+    return 1;   // ACK
+  }
+  else if ((read1 == 0x96) && (read2 == 0x96))
+  {
+    _debug->printf ("NACK\r\n");
+    return 0;   // NACK
+  }
+  else return 0;
+}
+
+bool HPM::stop_measurement(void)
+{
+    // First, we send the command
+    unsigned char stop_measurement[] = {0x68, 0x01, 0x01, 0x95 };
+    for (int i=0; i<sizeof(stop_measurement); i++)
+    {
+        _device->putc(stop_measurement[i]); 
+    }
+  
+  
+  //Then we wait for the response
+  while (!_device->readable()) {} // wait until chars arrive
+  char read1 = _device->getc();
+  char read2 = _device->getc();
+  
+  // Test the response
+  if ((read1 == 0xA5) && (read2 == 0xA5)){
+    return 1;   // ACK
+  }
+  else if ((read1 == 0x96) && (read2 == 0x96))
+  {
+    _debug->printf ("NACK\r\n");
+    return 0;   // NACK
+  }
+  else return 0;
+}
+
+bool HPM::read_measurement (long int &PM25, long int &PM10)
+{
+    // Send the command 0x68 0x01 0x04 0x93
+    unsigned char read_particle[] = {0x68, 0x01, 0x04, 0x93 };
+    for (int i=0; i<sizeof(read_particle); i++)
+    {
+        _device->putc(read_particle[i]);   
+    }
+  
+    // A measurement can return 0X9696 for NACK
+    // Or can return eight bytes if successful
+    // We wait for the first two bytes
+    while(!_device->readable());
+    unsigned char HEAD = _device->getc();
+    
+    while(!_device->readable());
+    unsigned char LEN = _device->getc();
+  
+    // Test the response
+    if ((HEAD == 0x96) && (LEN == 0x96))
+    {
+        _debug->printf("NACK");
+        return 0;
+    }
+    else if ((HEAD == 0x40) && (LEN == 0x05))
+    {
+        // The measuremet is valid, read the rest of the data 
+        // wait for the next byte
+        while(!_device->readable());
+        unsigned char COMD = _device->getc();
+        
+        while(!_device->readable());
+        unsigned char DF1 = _device->getc();
+        
+        while(!_device->readable());
+        unsigned char DF2 = _device->getc();
+             
+        while(!_device->readable());
+        unsigned char DF3 = _device->getc();
+           
+        while(!_device->readable());
+        unsigned char DF4 = _device->getc();
+         
+        while(!_device->readable());
+        unsigned char CS = _device->getc();
+          
+        // Now we shall verify the checksum
+        unsigned int cs_calc = 65536;
+        cs_calc -= HEAD - LEN - COMD - DF1 - DF2 - DF3 - DF4;
+        cs_calc %= 256;
+        
+        if (((0x10000 - HEAD - LEN - COMD - DF1 - DF2 - DF3 - DF4) % 0XFF) != CS)
+        {
+            _debug->printf("Checksum fail\r\n");
+            _debug->printf ("HEAD=%02x LEN=%02x COMD=%02x DF1=%02x DF2=%02x DF3=%02x DF4=%02x CS=%02x, cs_calc=%02x\r\n", HEAD, LEN, COMD, DF1, DF2, DF3, DF4, CS, cs_calc);
+            return 0;
+        }
+        else
+        {
+            // Checksum OK, we compute PM2.5 and PM10 values
+            PM25 = DF1 * 256 + DF2;
+            PM10 = DF3 * 256 + DF4;
+            return 1;
+        }
+    }
+    return 0;
+}
+
+bool HPM::stop_autosend(void)
+{
+    // Stop auto send
+    unsigned char stop_autosend[] = {0x68, 0x01, 0x20, 0x77 };
+    for (int i=0; i<sizeof(stop_autosend); i++)
+    {
+        _device->putc(stop_autosend[i]); 
+    }
+  
+  //Then we wait for the response
+  while(!_device->readable());
+  char read1 = _device->getc();
+  char read2 = _device->getc();
+  
+  // Test the response
+  if ((read1 == 0xA5) && (read2 == 0xA5)){
+    // ACK
+    return 1;
+  }
+  else if ((read1 == 0x96) && (read2 == 0x96))
+  {
+    // NACK
+    _debug->printf ("NACK\r\n");
+    return 0;
+  }
+  else return 0;
+}
+
+bool HPM::start_autosend(void)
+{
+    // Start auto send
+    unsigned char start_autosend[] = {0x68, 0x01, 0x40, 0x57 };
+    for (int i=0; i<sizeof(start_autosend); i++)
+    {
+        _device->putc(start_autosend[i]); 
+    }  
+
+  //Then we wait for the response
+  while(!_device->readable());
+  char read1 = _device->getc();
+  char read2 = _device->getc();
+  // Test the response
+  if ((read1 == 0xA5) && (read2 == 0xA5)){
+    // ACK
+    return 1;
+  }
+  else if ((read1 == 0x96) && (read2 == 0x96))
+  {
+    // NACK
+    _debug->printf ("NACK\r\n");
+    return 0;
+    
+  }
+  else return 0;
+}
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