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arduino:code_collection [2025/02/21 19:08] – vamsanarduino:code_collection [2025/03/22 22:54] (current) – [Float to char[]] vamsan
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 ====== LamaPLC: Arduino code collection ====== ====== LamaPLC: Arduino code collection ======
 +===== Frequently used code collection =====
 +==== TON ====
 +<code c>
 +  // var def block
 +  unsigned long startMillis, currentMillis;     // current and start time
 +  const unsigned long period = 2000;            // the value is a number of milliseconds
  
-===== Modbus =====+  // code block 
 +  currentMillis = millis();                     // get the current "time" (actually the number of milliseconds since the program started) 
 +  if (currentMillis - startMillis >= period)    // test whether the period has elapsed 
 +  { 
 +    startMillis = currentMillis;                // time update 
 +    // after time has elapsed the call 
 +    // ... 
 +  }   
 +</code> 
 + 
 +==== check serial monitor ==== 
 +<code c> 
 + 
 +  // code in setup() 
 +  Serial.begin(9600); 
 +   
 +  while (!Serial) { 
 +    ; // wait for serial port to connect. Needed for native USB port only 
 +  } 
 +  Serial.println("Serial monitor OK"); 
 +</code> 
 +===== Converting code collection ===== 
 +==== Float to char[] ==== 
 +<code c> 
 +// lib init (optional) 
 +#include "avr/dtostrf.h" 
 +// converting  
 +float a; 
 +char sendValue[10]; 
 +dtostrf (a, 10, 8, sendValue); // float_value, min_width, num_digits_after_decimal, where_to_store_string 
 + 
 +</code> 
 + 
 +==== Int to char[] ==== 
 +<code c> 
 +int a; 
 +char sendValue[10]; 
 +itoa (i,sendValue,10); // int value, char * str, int base 
 +// base:  Numerical base used to represent the value as a string, between 2 and 36, where 10 means decimal base, 16 hexadecimal, 8 octal, and 2 binary 
 + 
 +</code> 
 +==== String to char[] ==== 
 +<code c> 
 + 
 +char place[20]; 
 +strcpy(place,"Home"); 
 + 
 +</code> 
 +===== Modbus code collection =====
 ==== Convert 2 registers to float ==== ==== Convert 2 registers to float ====
 call: [float] = //modbus_2regs_2_float//([1.register], [2.register]) \\ call: [float] = //modbus_2regs_2_float//([1.register], [2.register]) \\
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 } }
 </code>  </code> 
 +
 +call: [float] = //modbus_2regs_2_float//([first register]) \\
 +
 +<code c>
 +float modbus_2regs_2_float(uint16_t addr) {
 +    uint16_t a = node.getResponseBuffer(addr);
 +    uint16_t b = node.getResponseBuffer(addr+1);
 +    uint32_t combined = ((uint32_t)a << 16) | b;
 +    float f;
 +    memcpy(&f, &combined, sizeof f);
 +    return f;
 +}
 +</code>
  
 ==== Convert float 2 registers  ==== ==== Convert float 2 registers  ====
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 </code> </code>
  
 +int32 convert direct to float by division by a thousand: \\
  
 +<code c>
 +float make_float_32bit_word(uint16_t hi_word, uint16_t lo_word)
 +{
 +    uint16_t words_16bit[2] = {hi_word, lo_word};
 +    uint32_t word_32bit = 0;
 +    float back;
 +
 +    memcpy(&word_32bit, words_16bit, 4);
 +    back = word_32bit / 1000.0;
 +    return back;
 +}
 +</code>
 +
 +call: [float] = //make_float_32bit_word//([first reg]) \\
 +
 +<code c>
 +float make_float_32bit_word(uint16_t addr)
 +{
 +    uint16_t words_16bit[2]; 
 +    words_16bit[1] = node.getResponseBuffer(addr);
 +    words_16bit[0] = node.getResponseBuffer(addr+1);
 +    uint32_t word_32bit = 0;
 +    float back;
 +
 +    memcpy(&word_32bit, words_16bit, 4);
 +    back = word_32bit / 1000.0;
 +    return back;
 +}
 +</code>
 ==== Float to / from one register ==== ==== Float to / from one register ====
 <color red>Note: The maximum value of the int16 type is 32767, so in this format only the value range 0 .. 327.67 can be stored with 2 decimal places!</color> <color red>Note: The maximum value of the int16 type is 32767, so in this format only the value range 0 .. 327.67 can be stored with 2 decimal places!</color>
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   Serial.println(tmpstr2);   Serial.println(tmpstr2);
   return false;   return false;
 +}
 +</code>
 +
 +===== General code collection =====
 +==== MAC random generator ====
 +Generate random MAC using pseudo random generator, bytes 0, 1 and 2 are static (MAC_START), bytes 3, 4 and 5 are generated randomly
 +<code c>
 +void generateMac() {
 +  // Marsaglia algorithm from https://github.com/RobTillaart/randomHelpers
 +  seed1 = 36969L * (seed1 & 65535L) + (seed1 >> 16);
 +  seed2 = 18000L * (seed2 & 65535L) + (seed2 >> 16);
 +  uint32_t randomBuffer = (seed1 << 16) + seed2; /* 32-bit random */
 +  memcpy(data.mac, MAC_START, 3);                // set first 3 bytes
 +  for (byte i = 0; i < 3; i++) {
 +    data.mac[i + 3] = randomBuffer & 0xFF;  // random last 3 bytes
 +    randomBuffer >>= 8;
 +  }
 } }
 </code> </code>