I have a problem with the Arduino communication. It's quite hard to describe so I cant fit it in the title. Anyway here are the following:
So I have this code for my receiving end:
if(Serial1.available())
{
while(Serial1.available())
{
uint8_t inByte = Serial1.read();
inByte = inByte ^ k;
Serial.write(inByte);
}
Serial.println(" done");
}
It's supposed to print in one line and print done when it's done. The Serial1.available() seems to skip the next Serial1.available(), I don't know what's going on. Anyway here's my current, bad, output:
h done
e done
l done
l done
o done
done
when it should be:
hello done
I'm sorry if this could've been phrased better but that's all I can type now, my brain is kinda in pain. I've never experienced this behavior in a Windows c++ console application.
If you are calling that routine in loop() then yes, it will read from the serial buffer and immediately return since you are probably not sending the data fast enough.
A better way to handle this sort of thing is to use a control char which indicates the end of a message OR if you have a specific data format you expect to receive, then keep a count of the chars which have come in until the data format limit is reached.
There is discussion here which you may find useful: Serial Duplex using Arduino Also there are example sketches that ship with the Arduino IDE: Menu: Examples: Communication:
Also, read all the entries under the Serial listing for Arduino. Good stuff there.
So the routine you develop for working with Serial input really depends on your project and the kind of data you are receiving. In your example above, if you were to use a control char, it might look like this:
while(Serial1.available()){
char c = Serial1.read();
if (c == '*'){
Serial.println(" done");
} else {
Serial.write(c);
}
}
Related
I use SIM800L GSM module to detect incoming calls and generally it works fine. The only problem is that sometimes it takes up to 8 RINGS before the GSM module tells arduino that someone is calling (before RING appears on the serial connection). It looks like a GSM Network congestion but I do not have such issues with normal calls (I mean calls between people). It happens to often - so it cannot be network/Provider overload. Does anybody else had such a problem?
ISP/Provider: Plus GSM in Poland
I don't put any code, because the problem is in different layer I think
sorry that I didn't answer earlier. I've tested it and it turned out that in bare minimum code it worked OK! I mean, I can see 'RING' on the serial monitor immediately after dialing the number. So it's not a hardware issue!
//bare minimum code:
void loop() {
if(serialSIM800.available()){
Serial.write(serialSIM800.read());
}
if(Serial.available()){
serialSIM800.write(Serial.read());
}
}
In my real code I need to compare calling number with the trusted list. To do that I saved all trusted numbers in the contact list on the sim card (with the common prefix name 'mytrusted'). So, in the main loop there's if statement:
while(mySerial.available()){
incomingByte = mySerial.read();
inputString += incomingByte;
}
if (inputString.indexOf("mytrusted") > 0){
isTrusted = 1;
Serial.println("A TRUSTED NUMBER IS CALLING");
}
After adding this "if condition" Arduino sometimes recognize trusted number after 1'st call, and sometimes after 4'th or 5'th. I'm not suspecting the if statement itself , but the preceding while loop, where incoming bytes are combined into one string.
Any ideas, what can be improved in this simply code?
It seems, I found workaround for my problem. I just send a simple 'AT' command every 20 seconds to SIM800L (it replies with 'OK' ). I use timer to count this 20 seconds interval (instead of simply delay function)
TimerObject *timer2 = new TimerObject(20000); //AT command interval
....
timer2->setOnTimer(&SendATCMD);
....
void SendATCMD () {
mySerial.println("AT");
timer2->Stop();
timer2->Start();
}
With this simple modification Arduino always sees incoming call immediately (after 1 ring)
I'm doing some experiments with Arduino+Siemens TC35 GSM module and I would like to be able to read an SMS that I send to this device.
I have assembled my device following more or less this scheme:
with the difference that I don't use a buzzer nor a relay, just an LCD display. You can see the full picture here:
The scheme should work, because for example I have been able to send an SMS from Arduino to my mobile phone, but I'm having some problems parsing the SMS I send to my Arduino.
(note: I will hide my number substituting some numbers with ***)
I initialize the GSM module like this:
mySerial.print("AT+CMGF=1\r\n");
and I try to read my SMS like this:
void readSMS()
{
mySerial.print("AT+CMGR=6\r\n");
delay(1000);
char c;
while (mySerial.available()>0){
c = (char)mySerial.read();
Serial.print(c);
}
}
but I always get a truncated SMS. This is what I see in my Serial monitor:
AT+CMGF=1
OK
AT+CMGR=6
+CMGR: "REC READ","AT+CMGR=6
+CMGR: "REC READ","+4475********",,"14/04/25,21:08:AT+CMGR=6
+CMGR: "REC READ","+4475********",,"14/04/25,21:08:AT+CMGR=6
+CMGR: "REC READ","+4475********",,"14/04/25,21:08:AT+CMGR=6
+CMGR: "REC READ","+4475********",,"14/04/25,21:08:AT+CMGR=6
what's wrong with my code?
Thank you so much for any help.
p.s: also other commands that are supposed to work (for example the one to delete all SMS: AT+CMGD=1,4) don't work at all and give me error.
p.p.s: I wish I could use the GSM.h library that is available for Arduino, but I guess it's only compatible with the original Arduino GSM Shield.
I'm not an Arduino expert in any capacity, so there may be better ways to do this in the API, but I'd try something like this (delays can probably be lowered)
void readSMS()
{
mySerial.print("AT+CMGR=6\r\n"); // Send request
int count = 5; // Number of 100ms intervals before
// assuming there is no more data
while(count-- != 0) { // Loop until count = 0
delay(100); // Delay 100ms
while (mySerial.available() > 0){ // If there is data, read it and reset
c = (char)mySerial.read(); // the counter, otherwise go try again
Serial.print(c);
count = 5;
}
}
}
Another - probably better - option would be to just loop without a delay until you get a complete answer. That of course assumes that you know what to look for (<cr><lf>OK<cr><lf> would seem to be the case here, but I'm too weak on the Hayes spec to be sure)
I am having hell with this and I know it is probably really simple. I am trying to read a text message from my Seeed GPRS shield. I have the shield setup as a software serial and I am displaying the information received from the GPRS to the serial monitor. I am currently sending all AT commands over serial while I work on my code. To display the data from the software serial to the serial monitor, I am using the following code.
while(GPRS.available()!=0) {
Serial.write(GPRS.read());
}
GPRS is my software serial obviously. The problem is, the text is long and I only get a few characters from it. Something like this.
+CMGR: "REC READ","1511","","13/12/09,14:34:54-24" Welcome to TM eos8
This text is a "Welcome to T-Mobile" text that is much longer. The last few characters shown are scrambled. I have done some research and have seen that I can mod the serial buffer size to 256 instead of the default 64. I want to avoid this because I am sure there is an easier way. Any ideas?
Have you tried reading into a character array, one byte at a time? See if this helps:
if (GPRS.available()) { // GPRS talking ..
while(GPRS.available()) { // As long as it is talking ..
buffer[count++]=GPRS.read();
// read char into array
if(count == 64) break; // Enough said!
}
Serial.write(buffer,count); // Display in Terminal
clearBufferArray();
count = 0;
}
You need to declare the variables 'buffer' and 'count' appropriately and define the function 'clearBufferArray()'
Let me know if this helps.
Looks like this is simply the result of the lack of flow control in all Arduino serial connections. If you cannot pace your GPRS() input byte sequence to a rate that guarantees the input FIFO can't overflow, then your Serial.write() will block when the output FIFO fills. At that point you will be dropping new GPRS input bytes on the floor until Serial output frees up more space.
Since the captured output is apparently clean up to about 64 bytes, this suggests
a) a 64 byte buffer,
b) a GPRS data rate much higher than the Serial one, and
c) that the garbage data is actually the occasional valid byte from later in the sequence.
You might confirm this by testing the return code from Serial.write. If you get back zero, that byte is getting lost.
If you were using 9600 for Serial and 57600 for GPRS, I would expect somewhat more than 64 bytes to come through before the output gets mangled, but if the GPRS rate is more than 64x the Serial rate, the entire output FIFO could fill up within a single output byte transmission time.
Capturing to an intermediate buffer should resolve your issue, as long as it is large enough for the whole message. Similarly, extending the size of either the source (in conjunction with testing the Serial.write) or destination (without any additional code) FIFOs to the maximum datagram size should work.
I've had the same problem trying to read messages and get 64 characters. I overcame it by adding a "delay(10)" in the loop calling the function that does the read from the GPRS. Seems to be enough to overcome the race scenario. - Using Arduino Mega.
void loop() {
ReadmyGPRS();
delay(10); //A race condition exists to get the data.
}
void ReadmyGPRS(){
if (Serial1.available()){ // if data is comming from GPRS serial port
count = 0; // reset counter
while(Serial1.available()) // reading data into char array
{
buffer[count++]=Serial1.read(); // writing data into array
if(count == 160)break;
}
Serial.write(buffer,count);
}
}
I am writing a small test program that attempts to perform a serial.write() followed by a serial.read() within an ISR. The code will eventually be used to prompt an external GSM shield to send an SMS on a regular basis.
ISR(TIMER2_OVF_vect) {
Serial.println("AT+CMGS=\"0123456789\""); // Tell Sim900 To prepare sms to number 01...
while(Serial.read()!='>'); // Wait for Sim900 to respond
Serial.print("A text message"); // the SMS body
Serial.write(0x1A); //Confirm send instruction
Serial.write(0x0D);
Serial.write(0x0A);
}
}
What I have found after a lot of testing is that Serial.read() within an ISR is not capable of reading a live serial prompt, instead it will only read any input that was buffered before the ISR was triggered.
Is there any way around this?
The only solution I have found is to place this code instead within the main loop(). But I want to send the SMS using a timer interrupt.
Thank you
You need to place the code in the loop() but using an IF:
float toBeSent = interval;
loop() {
if (millis() > toBeSent) {
Send();
toBeSent = milli() + interval;
}
}
interval is your sending interval in milliseconds.
I had a similar problem a while ago which I managed to resolve by using the Arduino SoftwareSerial library instead of the hardware based Serial.read.
There are some overheads associated with using SoftwareSerial, and you can only read one port at a time, so I leave it up to those with a better understanding of the Arduino platform to tell you if this is a good idea, but one of the benefits of this library is that you can use it within an ISR.
To use the SoftwareSerial library, add the following two lines of code at the top of your sketch remembering to replqce the rx_pin and tx_pin with the corresponding pin values you want to use:
#include <SoftwareSerial.h>
SoftwareSerial mySerial(rx_pin, tx_pin);
Then replace the key word Serial throughout your sketch with mySerial (or whatever name you have chosen to give your SoftwareSerial instance).
An important thing to keep in mind when using SoftwareSerial is that you can only use certain pins on the Arduino so read the documentation first.
If you wanted to live dangerously you could enable interrupts inside the ISR and use a flag to prevent reentry.
int flag=0;
ISR(TIMER2_OVF_vect) {
flag = 1
if (flag){return;}
sei();
Serial.println("AT+CMGS=\"0123456789\""); // Tell Sim900 To prepare sms to number 01...
while(Serial.read()!='>'); // Wait for Sim900 to respond
Serial.print("A text message"); // the SMS body
Serial.write(0x1A); //Confirm send instruction
Serial.write(0x0D);
Serial.write(0x0A);
}
flag = 0;
}
When I'm writing to the serial interface, I'm getting strange and unexpected output when my sketches first run. The output seems to be a variant of what should be printed:
eg:
String text1 = "foobar";
void setup() {
Serial.begin(9600);
Serial.print("\n");
Serial.print(text1);
}
void loop() {
}
Results in the output:
fo
foobar
(the new line appears before "fo" but I couldn't work out how to include it).
So some variant of whatever is supposed to be printed, gets printed before the actual text that is supposed to be printed. Changing the output, changes the anomalous text (sometimes it'll be two characters, sometimes three). Making changes that don't affect the output and recompiling has no effect on the anomalous text.
I'm a total Arduino newbie (I only started writing my own code today), but I can only assume this isn't normal.
I'm using a Freetronics EtherTen and the 1.0 IDE
thanks in advance
Arduino is restarting your sketch when you open its serial port on the computer.
so it prints out, and then initialized again.
after
Serial.begin(9600);
try to put either:
delay(500)
or
while (!Serial); // while the serial stream is not open, do nothing:
This is most likely a Serial communication Reset issue as Eran W pointed out. See my previous answer here.
The Arduino automatically resets when it receives serial communication from most things other than the Arduino IDE. This is why you can send from the IDE but not anything else.
I have an Uno and put a capacitor between Reset and Ground.Here's a page with some good info on the subject.
Good luck. http://arduino.cc/playground/Main/DisablingAutoResetOnSerialConnection
You should probably terminate your string with a 0.
Like:
String text1 = "foobar",0;