Using a for loop to store string with spi flash memory

Projects General Guidance
1

Hi
I’m hoping someone can help me, I have just started working with flash memory using the SPImemory library so I do apologize if this is something that is easy. I have a string of data 255,255,255 which represents a LED, I have 300 LED’s so I have 255,255,255 x 300, I want to store each string (each 255,255,255) inside the flash memory.

I had tried to store all of it into a string variable however that wastes a lot of space and doesn’t work so my idea was to store each led variable into a different memory address. Example address 0 = 255,255,255, address 1 = 255,255,255, address 3 = 255,255,255 etc, I believe this is the best way.

So I have a issues when it comes to storing all the data using a for loop as it doesn’t seem to work

#include <Tlc5940.h>

#include <SPIMemory.h>
SPIFlash flash;
#if defined(ARDUINO_SAMD_ZERO) && defined(SERIAL_PORT_USBVIRTUAL)
// Required for Serial on Zero based boards
#define Serial SERIAL_PORT_USBVIRTUAL
#endif

#if defined (SIMBLEE)
#define BAUD_RATE 250000
#define RANDPIN 1
#else
#define BAUD_RATE 115200
#if defined(ARCH_STM32)
#define RANDPIN PA0
#else
#define RANDPIN A0
#endif
#endif

String inputString;
//String inputString2;
String outputString;

String readString;
//uint32_t strAddr[3];

void setup() {
  // put your setup code here, to run once:
  Serial.begin(BAUD_RATE);
#if defined (ARDUINO_ARCH_SAMD) || (__AVR_ATmega32U4__) || defined(ARCH_STM32) || defined(NRF5)
  while (!Serial) ; // Wait for Serial monitor to open
#endif
  delay(50); //Time to terminal get connected
  //Serial.print(F("Initialising"));
  for (uint8_t i = 0; i < 10; ++i)
  {
    Serial.print(F("."));
  }
  Serial.println();
  randomSeed(analogRead(RANDPIN));
  flash.begin();

Serial.println("Start");
  
}

void loop() {
  // put your main code here, to run repeatedly:
while(Serial.available() > 0) {
    char c = Serial.read();  //gets one byte from serial buffer
    readString += c; //makes the string readString
    delay(5);  //slow looping to allow buffer to fill with next character
}
if (readString.length() >0) {
  if(readString == "Delete"){
    Delete();
  }
  if(readString == "Upload"){
    Upload();
  }
   if(readString == "Read"){
    Read();
  }
}
readString="";
}
void Delete() {
   Serial.println("Deleting.....");
  if (flash.eraseChip()){
    Serial.println(F("Chip erased"));
  }
  else {
    Serial.println(F("Error erasing chip"));
  }
  
}

void Upload() {
  Serial.println("Uploading.....");
inputString = "255,255,255";
for (uint8_t i = 0; i < 300; i++) {
  if (flash.writeStr(i, inputString)) {
    Serial.println("Writing Success");
  }
  else {
    Serial.println("Write Failed");
  }
}
Serial.println("Upload Finished");
}

void Read() {

for (uint8_t i = 0; i < 300; i++) {
flash.readStr(i, outputString);
  Serial.println(outputString);
}
Serial.println("Read Finished");
}

As you can see from my above code which im using for testing, the upload functions starts a for loop using the int i as the memory address to put the string variable into, however it doesn’t seem to work the way I imagined, this is where I need help

I also have the function to read those address back, which means I need to know which address I wrote to hence another for loop using int i as the address point to read from.

I hope this is understandable and any help would be great

Thank you

2 
flash.writeStr(i, inputString)

I am not familiar with the library or hardware that you are using. However, it looks likely that this function writes data to memory starting at address i

If that is so, then the next write will save data to address i+1 but the data is not a single byte so the second write will overwrite most of the previous data written

If I am right then can you see a problem ?

3

Hi

Thank you for the help i went about it a different way using bytes to store the data into addresses using for loop

byte testByte = 100;
for (int i = 0; i  < 200; i++) {
    if (flash.writeByte(i, testByte)) {
    Serial.println("Writing Success");
   // Serial.println(byteAddr[i]);
  }
  else {
    Serial.println("Write Failed");
    // Serial.println(byteAddr[i]);
  }
}
  delay(50);

that seemed to work however i have a number like 100 stored in each address which is a byte variable, is there a way to split the byte as an example

byte test = 100 
byte[0] = 1 
byte[1] = 0 
byte[2] = 0
4

If the value of number is base 10 then adapt this

void setup()
{
  Serial.begin(115200);
  while (!Serial);
  byte number = 123;
  byte hundreds = number / 100;
  byte tens = (number % 100) / 10;
  byte ones = (number % 10 );
  Serial.println(hundreds);
  Serial.println(tens);
  Serial.println(ones);
}

void loop()
{
}
5

Hi

Thank you i have tried it that way and honestily what i had in mind had some values with leading zeros so i decided to do this

 Outputs:
  Red : 1
  Green : 2
  Blue : 3
  Red And Green : 4
  Red And Blue : 5
  Green And Blue : 6
  All On : 7
  All Off : 8

so those numbers would represent the bytes i want to store, my problem now is that no matter what i do, honestly a bit frustrated i cant seem to read a value im sending to the serial and storing it as a byte. Example i type in 1, 2, 3 into the serial however the output comes out as 49,50,51 etc.... i have tried strings converting to byte and all i get is zeros i have tried converting int to bytes and i get random numbers. i am literally super lost

Thank you

6

Welcome to the wonderful world of ASCII. What you are seeing is the value of the characters representing 1, 2, 3 etc. If you want to turn them into real integers then subtract '0' (or 48) from the value received

7

Thank you so much that literally worked for me

8

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