I have a problem: I can read the EEPROM from my ATtiny, but I can't write something in it.
Here is my code:
#include <EEPROM.h>
int addr = 0;
int val = 2;
void setup()
{
}
void loop()
{
EEPROM.write(addr, val);
addr = addr + 1;
if (addr == 512)
addr = 0;
}
EDIT
Now my write code is:
#include <EEPROM.h>
int addr = 0;
int val = 2;
void setup()
{
}
void loop()
{
EEPROM.write(addr, byte(val));
addr = addr + 1;
if (addr == 512)
while(1);
}
And my read code:
int address = 0;
byte value;
#include <SoftwareSerial.h>
void setup()
{
SSerial.begin(9600);
}
void loop()
{
value = EEPROM.read(address);
SSerial.print(address);
SSerial.print("\t");
SSerial.print(value, DEC);
SSerial.println();
address = address + 1;
if (address == 512){
address = 0;
delay(100000000);
}
}
I always get only teh value 255. On every adress.
Now I convert my int to byte. My int won't get over 255 in my case.
And by the way: can I create an int as byte? So I can use it like a normal int, but can write it directly?
You're writing a single byte, whereas an int is two bytes. You can use EEPROM.get() & EEPROM.put() for larger types (read/write only handle a single byte).
#include <EEPROM.h>
int addr = 0;
int val = 2;
void setup(){}
void loop(){
//Write value
EEPROM.put(addr, val);
//Read value
EEPROM.get(addr, val);
addr += sizeof(int); //Increment cursor by two otherwise writes will overlap.
if(addr == EEPROM.length())
addr = 0;
}
as Vladimir Tsykunov mentioned, this test code can be bad for your EEPROM as it will loop many times while running. It may be better to stop the loop after one iteration:
if(addr == EEPROM.length())
while(1); //Infinite loop
Try not write eeprom in a loop, i suppose, eeprom have limited number of write/read cycles. You should show values that you read and write in terminal.
Related
I am trying to print all the sram contents and i expect to find the global variables declared in the code to be at Ox100. But it seems like they are not allocated at all. granted i am not using the variables anywhere in the code but i would still expect them to be allocated memory. Another thing to note is that even if i keep adding var in the code the Global variable usage seems to hold steady with message below. What am i missing? Some compiler optimization?
Global variables use 184 bytes (8%) of dynamic memory, leaving 1864 bytes for local variables. Maximum is 2048 bytes.
int var1 = 100;
int var2 = 100;
int var3 = 100;
int var4 = 100;
int var5 = 100;
int var6 = 100;
void setup() {
UCSR0B = (1 << TXEN0); //Enable the serial output
UBRR0L = 16; //Set the baud rate to 57600bps
memory_dump1(); //Execute to the memory_dump subroutine
}
void loop(){
int var2 = var1;
delay(5000);
memory_dump1();
}
void memory_dump1(){
uint16_t address;
uint8_t byte_at_address, new_line;
address = 0x0100;
int byteCount = 0;
while (address <= 0x08FF) {
byte_at_address = *(byte *)address;
Serial.print (byte_at_address,HEX);
Serial.print ('\t');
address++;
byteCount ++;
if ( byteCount % 8 == 0 ){
Serial.print ('\n');
}
}
}
The keyword volatile might help...
// volatile /* 9 byte, or 209 byte RAM if the // is removed */
int dummy_data[100];
void setup() { }
void loop() { }
Sample compiled for an Arduino Nano with IDE 1.8.9
int dummy_data[100] { 1,2,3,4,5,6 };
void dumpRAM (const char* name, void* adr, size_t size) {
unsigned int iadr = (unsigned int) adr;
Serial.print("0x");
if (iadr < 0x1000) Serial.write('0');
if (iadr < 0x100) Serial.write('0');
if (iadr < 0x10) Serial.write('0');
Serial.print (iadr, HEX);
Serial.print (": ");
Serial.println (name);
byte* bp = (byte*) adr;
for (size_t i = 0; i < size;) {
Serial.write (' '); if(*bp <0x10) Serial.write('0');
Serial.print( *bp++, HEX);
if ( (++i & 0x0F) == 0) // every 16 byte
Serial.println();
}
}
void setup() {
Serial.begin(9600);
dumpRAM("dummy_data", dummy_data, sizeof(dummy_data));
}
This helps to use your variable (thus avoids opitimizing it away), shows its content and address.
I want to write some text into the flash memory of an Arduino ESP32. It works kinda but not as I want it to.
void writeString(const char* toStore, int startAddr) {
int i = 0;
for (; i < LENGTH(toStore); i++) {
EEPROM.write(startAddr + i, toStore[i]);
}
EEPROM.write(startAddr + i, '\0');
EEPROM.commit();
}
My call
writeString("TEST_STRING_TO_WRITE", 0);
only writes TEST into the memory. I do not understand why. Is that because of the _? Or am I missing something different?
Here is the used LENGTH macro
#define LENGTH(x) (sizeof(x)/sizeof(x[0]))
and the method I use to read the string from the memory again (which seems to work correctly):
String readStringFromFlash(int startAddr) {
char in[128];
char curIn;
int i = 0;
curIn = EEPROM.read(startAddr);
for (; i < 128; i++) {
curIn = EEPROM.read(startAddr + i);
in[i] = curIn;
}
return String(in);
}
Where on earth did you get that LENGTH macro from? It’s surreal.
sizeof will not do what you want here. It’s a compile-time function that computes the storage requirements of its argument. In this case it should return the length in bytes of a character pointer, not the string it points to.
You want to use strlen(), assuming your char* is a properly terminated C string. Add one to make sure the ‘\0’ at the end gets stored, too.
#define LENGTH(x) (strlen(x) + 1)
Below is the code to demonstrate the storing as well as retrieving of the string ssid in the EEPROM (permanent storage).
#include "EEPROM.h"
int addr = 0;
#define EEPROM_SIZE 64
// the sample text which we are storing in EEPROM
char ssid[64] = "CARNIVAL OF RUST";
void setup() {
Serial.begin(115200);
Serial.println("starting now...");
if (!EEPROM.begin(EEPROM_SIZE)) {
Serial.println("failed to init EEPROM");
while(1);
}
// writing byte-by-byte to EEPROM
for (int i = 0; i < EEPROM_SIZE; i++) {
EEPROM.write(addr, ssid[i]);
addr += 1;
}
EEPROM.commit();
// reading byte-by-byte from EEPROM
for (int i = 0; i < EEPROM_SIZE; i++) {
byte readValue = EEPROM.read(i);
if (readValue == 0) {
break;
}
char readValueChar = char(readValue);
Serial.print(readValueChar);
}
}
void loop() {
}
Appreciate your time.
I am trying to convert "String" read from serial port in serialEvent() of Arduino IDE to integer values with exact representation.
For eg, if String myString = 200 then int myInt should be 200.
I have been somewhat successful but unable to convert String to exact int representation beyond 255.
Solutions I have tried:
1) used .toInt() function in Arduino.
2) used "atoi" and "atol" functions.
3) Serial.parseInt() in loop().
All of these methods start recounting from 0 after every 255 values.
I can't use parseInt since it only works inside loop(). My application requires to store variable value permanently until another value is given through port. For this Arduino Due's flash memory has been used.
The memory storing code seems to work only inside serialEvent().
Code snippet is as below:
#include <stdlib.h>
#include <DueFlashStorage.h>
DueFlashStorage memory;
String x = " ";
int x_size;
int threshold;
void setup(){
Serial.begin(115200);
}
void loop{
Serial.println(memory.read(0));
}
void serialEvent(){
while(Serial.available()){
x = Serial.readStringUntil('\n');
x_size = x.length();
char a[x_size+1];
x.toCharArray(a, x_size+1);
threshold = atoi(a);
memory.write(0, threshold);
}
}
1) Function .toInt() returns LONG and you want INT (I don't know why honestly but it is in documentation)... you need to cast it like this (tried on Arduino ATMEGA and it worked):
#include <stdlib.h>
String x = "1000";
int x_ = 0;
void setup() {
Serial.begin(9600);
}
void loop() {
x_ = (int) x.toInt();
Serial.println(x_);
delay(1000);
}
2) I’m not professional ... but serilEvent() is really old way of doing things and it isn't recommended to use it. You can do it "manually" in the loop() function.
You're only converting 1 character a time, that's why the limit is 255.
If you're not doing anything else, you could stay in a serial.read-loop until all characters are read. For example:
void loop() {
if(Serial.available()) {
byte count = 0;
char number[10]; // determine max size of array
bool wait = true;
while(wait) { // stay in this loop until newline is read
if(Serial.available()) {
number[count] = Serial.read();
if (number[count] == '\n') {
wait = false; // exit while loop
}
count++;
}
}
int threshold = atoi(number);
memory.write(0, threshold);
}
}
For the lack of a good function in Arduino IDE for char/String type to int type conversion (has a limit of 255), I wrote my own conversion code which seems to work perfectly.
int finalcount=0;
void setup(){
Serial.begin(115200);
}
void loop(){
if(Serial.available()) {
int count = 0;
char number[5]; // determine max size of array as 5
bool wait = true;
while(wait) { // stay in this loop until newline is read
if(Serial.available()) {
number[count] = Serial.read();
if (number[count] == '\n') {
finalcount = count; //max array size for integer; could be less than 5
wait = false; // exit while loop
}
count++;
}
}
int val[finalcount]; //array size determined for integer
int placeValue;
int finalval[finalcount];
int temp=0;
int threshold;
for(int i = 0; i<finalcount; i++){
val[i] = (int)number[i]-48; //convert each char to integer separately
placeValue = pow(10,(finalcount-1)-i); //calculate place value with a base of 10
finalval[i] = val[i]*placeValue; //update integers with their place value
temp += finalval[i] ; //add all integers
threshold = temp; //resulting number stored as threshold
}
Serial.println(threshold); //prints beyond 255 successfully !
}
}
I solved the problem using highByte and lowByte functions of Arduino. Works flawlessly.
#include <DueFlashStorage.h>
DueFlashStorage m;
byte a1,a2;
int val;
void setup() {
Serial.begin(115200); //start the serial communication
}
void loop()
{
if (Serial.available()>0)
{
val = Serial.parseInt(); //read the integer value from series
if(val>0){
a1 = highByte(val); //get the higher order or leftmost byte
a2 = lowByte(val); //get the lower order or rightmost byte
m.write(0,a1); //save in arduino due flash memory address 0
m.write(1,a2); //save in arduino due flash memory address 1
}
int myInteger;
myInteger = (m.read(0)*256)+m.read(1); //convert into the true integer value
Serial.println(myInteger);
}
I am using keil c51 compiler. I transmit data from my pc to MCU using serial port it works best.
When I transmit data from my MCU to PC then also it works best.
But when I transmit data to MCU and then store it to buffer character pointer and again from that character pointer buffer I transmit return to PC then it does not work and give garbage values?
My code for both function as below.
#include <REG51.H>
#include "uart.c"
void delay_ms(unsigned int x) // delays x msec (at fosc=11.0592MHz)
{
unsigned char j=0;
while(x-- > 0)
{
for (j=0; j<125; j++){;}
}
}
sbit SW = P3^2;
sbit LED = P3^3;
bit x = 0;
void main ()
{
char *buf;
int len=0;
int len1 = 0;
uart_init();
while(1){
if(RI == 1){
UART_RxString(buf,&len);
buf -= (len-1) ;
x = 1;
}
if(x == 1 && SW == 0){
UART_TxString(buf,&len1);
x = 0;
}
}
}
And below are the functions.
1.
void UART_TxString(char *string_ptr, int *l)
{
int count = 0;
while(*string_ptr){
UART_TxChar(*string_ptr++);
count++;
}
*l = count;
}
void UART_RxString(char *string_ptr, int *l)
{
char ch;
int count = 0;
while(1)
{
ch=UART_RxChar(); //Reaceive a char
//UART_TxChar(ch); //Echo back the received char
count++;
if((ch=='\r') || (ch=='\n')) //read till enter key is pressed
{ //once enter key is pressed
*string_ptr=0; //null terminate the string
break; //and break the loop
}
*string_ptr=ch; //copy the char into string.
string_ptr++; //and increment the pointer
}
*l = count;
}
I communicate with Arduino via Serial using a program that sends a series of bytes.
In order for the Arduino to realize it is receiving a message rather than junk, I have tagged the start of my byte array with the chars 'S' 'T' 'A' 'R' 'T'. After this will eventually follow a series of bytes that will be assigned to internal variables (not yet implemented).
The Arduino must read each byte sequentially and compare it to the byte array and if all are present in the correct order it will continue with the next part of the program, otherwise it will should discard current byte and wait for more bytes to arrive.
I am trying to implement it in the most efficient and readable way rather than using a series of nested if statements.
So far I have got:
byte inByte = 0;
byte handShake[] = {'S','T','A','R','T'};
void setup() {
Serial.begin(9600);
}
void loop()
{
while (Serial.available())
{
for (int x =0; x < sizeof(handShake) ; x++)
{
inByte = Serial.read();
Serial.println(x);
if (inByte == handShake[x])
{
if (x == (sizeof(handShake)-1)) {setArduino();}
}
else break;
}
}
}
void setArduino () {
Serial.println("Ready To Set Parameters");
}
This however doesn't seem to get past the second byte and I'm not sure why.
Worked it out :
Here is the answer:
byte inByte = 0;
char handShake[] = {'S','T','A','R','T'};
void setup() {
Serial.begin(9600);
}
void loop()
{
while (Serial.available())
{
for (int x =0; x < sizeof(handShake) ; x++)
{
inByte = Serial.read();
Serial.println(x);
if (inByte == handShake[x])
{
if (x == (sizeof(handShake)-1)) {setArduino();}
while(!Serial.available()) {delay(1);}
}
else {break;}
}
}
}
void setArduino () {
Serial.println("Ready To Set Parameters");
}
This may not be the most efficient way perhaps, but I can't see a problem with it currently.
Better answer : This allows the rest of the loop to iterate while waiting for the message to finish and if the full handshake message isn't received the counter will reset.
byte inByte = 0;
char handShake[] = {'S','T','A','R','T'};
int messageIndex = 0;
void setup() {
Serial.begin(9600);
}
void loop()
{
while (Serial.available())
{
inByte = Serial.read();
Serial.println(messageIndex);
if (inByte == handShake[messageIndex])
{
messageIndex++;
if (messageIndex == sizeof(handShake)) {messageIndex = 0; setArduino();}
}
else {messageIndex=0;}
}
// Other code while waiting for message to finish
Serial.println("tick");
}
void setArduino () {
Serial.println("Ready To Set Parameters");
}
You could try to calculate your message. CRC is old and good solution. I use it and it works perfect for me. I am not sure what kind of device are you communicating with.
//define
const uint32_t Polynomial = 0xEDB88320;
const uint16_t NumBytes = 256;
uint8_t data[NumBytes];
/// compute CRC32
uint32_t crc32_bitwise(const void* data, uint16_t length, uint32_t previousCrc32 = 0)
{
uint32_t crc = ~previousCrc32; // same as previousCrc32 ^ 0xFFFFFFFF
uint8_t* current = (uint8_t*) data;
while (length--)
{
crc ^= *current++;
for (uint8_t j = 0; j < 8; j++)
{
uint8_t lowestBit = crc & 1;
crc >>= 1;
if (lowestBit)
crc ^= Polynomial;
}
}
return ~crc; // same as crc ^ 0xFFFFFFFF
}
void setup() {
// put your setup code here, to run once:
}
void loop() {
// put your main code here, to run repeatedly:
}
when you need to calculate CRC
uint32_t crc = crc32_bitwise(data_bytes, sizeof(data_bytes));
data_bytes is byte array.
Then you can get all settings or message in byte data[x] and calculate CRC. Then you can add CRC to the message and send message byte data[x+sizeof(CRC)]
P.S. Use byte instead of int. For ex. for(byte x =0; x<sizeof(handShake); x++)