Hey guys,
I'm new to these Arduino and electronics stuffs.I just wanted to know how to reset the chip using code.
I just want to know the general syntax.
Thanks
Hello,
Generally, you don't need to reset your arduino. If you have a problem and only a reset will fix it, then it's not a good solution. It would be better to find what is causing the problem and fix that instead. That said, http://www.instructables.com/id/two-ways-to-reset-arduino-in-software/
void software_reboot()
{
asm volatile (" jmp 0");
}
That just restarts the code from the beginning. None of the hardware is reset.
There have been a lot of posts about it, I suggest you Google them. Using the watchdog timer is one way.
However generally speaking you shouldn't need to.
Driving the /RESET pin low from another pin is not one of the recommended ways.
stoutfiles:
void software_reboot()
{
asm volatile (" jmp 0");
}
This is not exactly the same as a reset. It does not set the I/O pins to their default state, it does not reset timers etc. I would not recommend it.
Here is:
Once again, you shouldn't need to reset the processor, any more than you turn off your car's ignition when you are going down a hill. If there is a problem, fix it.
Fixing the problem is not always an option. If the error occurs in a library or in some firmware there is no way. Not even the watchdog might solve it. I once had that problem, and I decided to pull the plug - by means of an ATtiny:
Hi!
I found this method to reset a function:
(step2)
void(* resetFunc) (void) = 0;//declare reset function at address 0
...
resetFunc(); //call reset
I use this reset, and it works fine.
How can I get a String, int, or variable from the function that I want to reset?
I use a string (IPis) that I declare at the start of the code (in the loop).
And In a void (sendGet) this string will contain for me important information, but I need to reset this void.
And after that the string loss the information.
How can I save that?
here is the part of the code:
void sendGET()
{
if (Ethernet.begin(mac) == 0) {
//Serial.println("Failed to configure Ethernet using DHCP");
// no point in carrying on, so do nothing forevermore:
while(true);
}
Serial.begin(9600);
Serial.println(F("Get ip from ipify")); // so I can keep track of what is loaded
if (client2.connect(serverName, 80)) { //starts client connection, checks for connection
Serial.println(F("connected"));
client2.println(F("GET / HTTP/1.0")); //download text
client2.println(F("Host: api.ipify.org"));
client2.println(); //end of get request
}
else {
Serial.println(F("connection failed")); //error message if no client connect
Serial.println();
}
while(client2.connected() && !client2.available()) delay(1); //waits for data
while (client2.connected() || client2.available()) { //connected or data available
char e = client2.read(); //gets byte from ethernet buffer
if (IPis.length() < 180){ //original lenght: 30
IPis += (e);
}
//Serial.print(e); //prints byte to serial monitor
}
IPis = IPis.substring((IPis.length())-13,IPis.length()); //153-166
//IPis = "192.168.2.24"; //only for test
Serial.println(IPis);
Serial.println();
Serial.println(F("disconnecting."));
Serial.println(F("=================="));
Serial.println();
client2.stop(); //stop client
delay(59000);
resetFunc(); //call reset
}
IPis the string that contain the information, and that I want to save out this void.
It is declare beforethis void.
Is there a procedure, that can save out the infromation from the voit that I have to reset?
And In a void (sendGet) this
C and C++ do NOT have voids. They have functions!
If you want the function to return a value, why the hell is it's return type void (which means that is returns nothing)?
Technically void is the type which has no value, its a C hack to be able to specify a subroutine
as if it were a function. A language-agnostic term is procedure, routine or subroutine.
1 Like
katonafull:
void(* resetFunc) (void) = 0;//declare reset function at address 0
...
resetFunc(); //call reset
That does not reset the chip. It merely starts execution back at the first instruction.
mudassir9999:
how to reset the chip using code.
That would be a complete waste of time.
- If your program is working there is no need for a reset.
- If your program crashes your code won't be able to make it reset.
The Atmel chips have a Watchdog Timer (WDT) which can be used to restart after a crash.
...R
Excuse me! My expressions was wrong. Im' not a professional programmer. I'm only a starter arduino user. I don't have to reset the chip. I just use an arduono ethernet shield with 2 libraries in one code. That is, first I need to the ethernet shield to work as a web client. And aftet that I need to the ethernet client to connect to an external server. And after that I nedd to the shield to works again like a webclient.
But after the connection to the external server the ethernet shield don't works like a webserver. The webpage is not available anymore.
So I need to "reset" the ethernet shield. I know this is
void(* resetFunc) (void) = 0;//declare reset function at address 0
...
resetFunc(); //call reset
not a real reset, but it is works fine for me. If I use this "resetFunc" after the connection to the external server the ethernet shield works fine again like a webclient.
Thi is te part of the code, when the shield connet to the external server, and this is the subrutine after that I need to "reset" the code:
void sendGET()
{
if (Ethernet.begin(mac) == 0) {
//Serial.println("Failed to configure Ethernet using DHCP");
// no point in carrying on, so do nothing forevermore:
while(true);
}
Serial.begin(9600);
Serial.println(F("Get ip from ipify")); // so I can keep track of what is loaded
if (client2.connect(serverName, 80)) { //starts client connection, checks for connection
Serial.println(F("connected"));
client2.println(F("GET / HTTP/1.0")); //download text
client2.println(F("Host: api.ipify.org"));
client2.println(); //end of get request
}
else {
Serial.println(F("connection failed")); //error message if no client connect
Serial.println();
}
while(client2.connected() && !client2.available()) delay(1); //waits for data
while (client2.connected() || client2.available()) { //connected or data available
char e = client2.read(); //gets byte from ethernet buffer
if (IPis.length() < 180){ //original lenght: 30
IPis += (e);
}
//Serial.print(e); //prints byte to serial monitor
}
IPis = IPis.substring((IPis.length())-13,IPis.length()); //153-166
//IPis = "192.168.2.24"; //only for test
Serial.println(IPis);
Serial.println();
Serial.println(F("disconnecting."));
Serial.println(F("=================="));
Serial.println();
client2.stop(); //stop client
delay(59000);
resetFunc(); //call reset
}
But my problem is: I need to get an information ( a string, or if I have to convert so an interval ) when the ethernet shield connect to an external server. This is the "IPis" string what is declared before the sendGet subrutine and it is contain the public IP. And I need this information after the "not real reset" too.
But if I "reset" the sendGet() subrutine the "IPis String" will be empty. Other strings outside the sendGet subrutine remain untouched.
So the question: How can I save the IPis string?
Is there a method to save the IP into the memory?
First of all, after the reset, no value is guaranteed in previously used variables. The code starts from the beginning and you have come to realize that each variable is initialized somehow, somewhere.
The variables are stored in memory - SRAM which is volatile. If you want to have guaranteed value it is good to save it in nonvolatile memory: flash or EEPROM.
You have to show how the variable is defined.
katonafull:
So I need to "reset" the ethernet shield. I know this is
Can't you do that without resetting the Arduino?
If you have code in setup() to initialize the ethernet shield you could put that in a function and call the function from setup() and from anywhere else you need to use it.
...R
Ethernet shield could have a reset pin. Maybe just digital I/O could be enough.
Budvar10:
First of all, after the reset, no value is guaranteed in previously used variables. The code starts from the beginning and you have come to realize that each variable is initialized somehow, somewhere.
The variables are stored in memory - SRAM which is volatile. If you want to have guaranteed value it is good to save it in nonvolatile memory: flash or EEPROM.
You have to show how the variable is defined.
Thanks! So I need to write the string into the flash or the eeprom. I declare the string before the "void setup()" in this way:String IPis; So if i'm not wrong it is a string class. Then next time the IPis string will used in the "sendGet" subrutine.
void sendGET() //client function to send/receive GET request data.
{
if (Ethernet.begin(mac) == 0) {
//Serial.println("Failed to configure Ethernet using DHCP");
// no point in carrying on, so do nothing forevermore:
while(true);
}
Serial.begin(9600);
Serial.println(F("Get ip from ipify")); // so I can keep track of what is loaded
if (client2.connect(serverName, 80)) { //starts client connection, checks for connection
Serial.println(F("connected"));
client2.println(F("GET / HTTP/1.0")); //download text
client2.println(F("Host: api.ipify.org"));
client2.println(); //end of get request
}
else {
Serial.println(F("connection failed")); //error message if no client connect
Serial.println();
}
while(client2.connected() && !client2.available()) delay(1); //waits for data
while (client2.connected() || client2.available()) { //connected or data available
char e = client2.read(); //gets byte from ethernet buffer
if (IPis.length() < 180){ //original lenght: 30
IPis += (e);
}
//Serial.print(e); //prints byte to serial monitor
}
IPis = IPis.substring((IPis.length())-13,IPis.length()); //153-166
//IPis = "192.168.2.24"; //only for test
Serial.println(IPis);
Serial.println();
Serial.println(F("disconnecting."));
Serial.println(F("=================="));
Serial.println();
client2.stop(); //stop client
delay(59000);
resetFunc(); //call reset
}
The "IPis" string will contain an ip, something like this:87.135.24.213
I can't use the F() Macro. How should I write the "IPis" string into the flash or eeprom? Or should I ask it in an other topic?
Robin2:
Can't you do that without resetting the Arduino?
I don't reset the arduino. I reset only the program.
If I know a solution, a command, or anithing else to reset only the ethernet shield and only in the softwear I would use that. But I don't know in addition this method.
I don't understand your suggestion:
Robin2:
If you have code in setup() to initialize the ethernet shield you could put that in a function and call the function from setup() and from anywhere else you need to use it.
Could you show me an example?