Hi,
I've a problem interfacing arduino with a python program that I've written. I'd like to read a string of 231 char at least ten time per second. When I try to read the strings I see that the entire message is broken in more strings (not the buffer size) randomly in time.
Baudrate is 115200.
Can anyone help me in solving this problem?
Thank you in advance,
Can you post your code, both Arduino and Python? That makes it easier for us to give some advice.
ok,
void setup() {
int i;
Serial.begin(115200);
pinMode(outPin1,OUTPUT);
pinMode(outPin2,OUTPUT);
pinMode(outPin3,OUTPUT);
flag=0;
j=0;
for (i=0; i<pidPinNum; i++) {
Input[i] = myPID[i].getInput();
myPID[i].SetMode(AUTOMATIC);
myPID[i].setNTCcoefficents(-4.16734e-4,6.4803e-4,-2.0405e-6);
}
}
void loop() {
unsigned long start = millis();
double f_value;
int i_value,i_string,i,k;
char signal_type;
if (start-previous > interval) {
//Serial.println("Alive");
Serial.print("#A00#");
Serial.print(analogRead(tempPin0));
Serial.print("#A01#");
Serial.print(analogRead(tempPin1));
Serial.print("#A02#");
Serial.print(analogRead(tempPin2));
/*
Serial.print("#s00#"); Serial.print(Setpoint,6);
Serial.print("#p00#"); Serial.print(consKp,6);
Serial.print("#i00#"); Serial.print(consKi,6);
Serial.print("#d00#"); Serial.print(consKd,6);
*/
for (k=0; k<pidPinNum; k++) {
for (i=0; i<100; i++) { string[i]='\0';} Serial.print("#s0"); Serial.print(myPID[k].pinOutput); Serial.print("#"); dtostre(Setpoint[k] ,string,4,' '); Serial.print(string);
for (i=0; i<100; i++) { string[i]='\0';} Serial.print("#p0"); Serial.print(myPID[k].pinOutput); Serial.print("#"); dtostre(myPID[k].abKp,string,4,' '); Serial.print(string);
for (i=0; i<100; i++) { string[i]='\0';} Serial.print("#i0"); Serial.print(myPID[k].pinOutput); Serial.print("#"); dtostre(myPID[k].abKi,string,4,' '); Serial.print(string);
for (i=0; i<100; i++) { string[i]='\0';} Serial.print("#d0"); Serial.print(myPID[k].pinOutput); Serial.print("#"); dtostre(myPID[k].abKd,string,4,' '); Serial.print(string);
Serial.print("#m");Serial.print(myPID[k].pinOutput); Serial.print("#00"); Serial.print(myPID[k].GetMode());
Serial.print("#o0");Serial.print(myPID[k].pinOutput); Serial.print("#");
Serial.print(Output[k]);
Serial.print("#I0");Serial.print(myPID[k].pinOutput); Serial.print("#");
Serial.print(myPID[k].getInput());
}
and the python side
class gui_arduino:
def __init__(self,parent):
self.win_os = False
self.ser_var = ""
try:
self.ser = serial.Serial('/dev/tty.usbmodem1d11', 115200)
#self.t = threading.Thread(target=self.serial_reader)
#self.t.start()
except:
try:
self.ser = serial.Serial('/dev/tty.usbmodem1a21', 115200)
except:
try:
self.ser = serial.Serial(port='COM4', baudrate=115200, dsrdtr=True)
#self.ser.databits=4
print self.ser
except:
self.win_os = True
def read_values(self):
self.ser_var=self.ser.read(self.ser.inWaiting())
if len(self.ser_var)>0:
print self.ser_var
ser_dict = {}
ser_list = self.ser_var.split("#")
#print ser_list
try:
ser_list.remove('')
except ValueError:
print "***********************Value Error"
if len(ser_list) > 0:
for i in range(0,len(ser_list)-1,2):
ser_dict[ser_list[i]]=ser_list[i+1]
#print ser_dict
for key,item in ser_dict.items():
if 'A' in key :
try:
T=self.voltage2temperature(item)
#print key
#print key.split("A")[1]
#print T
self.AI_values["AI_%d"%(int(key.split("A")[1]))].set(T)
except KeyError:
pass
except ValueError:
pass
elif 'D' in key:
try:
self.DI_values["DI_%d"%(int(key.split("D")[1]))].set(item)
except ValueError:
pass
except KeyError:
pass
elif 'm' in key:
#print "%02d"%int(key.split("m")[1])
try:
button = self.AUTO_buttons["%02d"%int(key.split("m")[1])]
if button.getState() != int(item) :
button.setState(int(item))
except KeyError:
pass
elif 'I' in key:
self.PID_signals[key].set(item)
self.voltage2temperature(1023.)
elif 'o' in key:
self.PID_signals[key].set(item)
else:
try:
if self.PID_entry[key][1] == True:
#print "here1: "+key+" "+item
self.PID_entry[key][0].set(item)
except:
pass
self.root.after(sampling_time,self.read_values)
Obviously it's only a part of the code. Let me know if you want to know more.
Thanks,
Please post the whole code ................. as I cannot see the datatypes of vars and initialized value you use..... I cannot test the code here .....
OK,
What is the output of the Arduino sketch when you capture it with the serial monitor?
Does it shows the output you expect?
if so we can consider the arduino code to be correct,
if not what did you expect ?
Also, with your python code you should be more explicit in which exceptions you care to catch. The way the code is written any number of bad exceptions will be silently caught and ignored. Therefore, only catch the exceptions you know should cause that sequence of events and allow the other exceptions to alert you when you have exceptional behavior.
Very good,
I try to explain the problem with a more simple and detailed example:
Arduino side:
long interval = 100;
long previous = 0;
void setup() {
Serial.begin(115200);
}
void loop() {
unsigned long start = millis();
if (start-previous > interval) {
Serial.print("1234567890#0#1234567890#1#1234567890#2#1234567890#3#1234567890#4#1234567890#5#1234567890#6#1234567890#7#1234567890#8#1234567890#9#1234567890#10#1234567890#11#1234567890#12#1234567890#13#1234567890#14#1234567890");
previous = start;
}
}
Pyhton side:
import time
import serial
if __name__ == '__main__':
start = time.time()
pass
ser = serial.Serial(port='COM4', baudrate=115200, dsrdtr=True)
while 1:
ser_var=ser.read(ser.inWaiting())
print time.asctime()+" "+ser_var
time.sleep(0.1)
if time.time()-start > 10:
break
ser.close()
print "serial port close"
the output
Fri May 18 17:18:03 2012
Fri May 18 17:18:03 2012 1234567890#0#1234567890#1#1234567890#2#1234567890#3#1234567890#4#1234567890#5#1234567890#6#1234567890#7#1234567890#8#1234567890#9#1234567890#10#1234567890#11#1234567890#12#1234567890#13#1234567890#14#1234567890
Fri May 18 17:18:03 2012 1234567890#0#1234567890#1#1234567890#2#1234567890#3#1234567890#4#1234567890#5#1234567890#6#1234567890#7#1234567890#8#1234567890#9#1234567890#10#1234567890#11#1234567890#12#1234567890#13#1234567890#14#1234567890
Fri May 18 17:18:03 2012 1234567890#0#1234567890#1#1234567890#2#1234567890#3#1234567890#4#1234567890#5#1234567890#6#1234567890#7#1234567890#8#1234567890#9#1234567890#10#1234567890#11#1234567890#12#1234567890#13#1234567890#14#1234567890
Fri May 18 17:18:03 2012 1234567890#0#1234567890#1#1234567890#2#1234567890#3#1234567890#4#1234567890#5#1234567890#6#1234567890#7#1234567890#8#1234567890#9#1234567890#10#1234567890#11#1234567890#12#1234567890#13#1234567890#14#1234567890
Fri May 18 17:18:04 2012 1234567890#0#1234567890#1#1234567890#2#1234567890#3#1234567890#4#1234567890#5#1234567890#6#1234567890#7#1234567890#8#1234567890#9#1234567890#10#1234567890#11#1234567890#12#1234567890#13#1234567890#14#12345678901234567890#0#1234567890#1#1234567890
Fri May 18 17:18:04 2012 #2#1234567890#3#1234567890#4#1234567890#5#1234567890#6#1234567890#7#1234567890#8#1234567890#9#1234567890#10#1234567890#11#1234567890#12#1234567890#13#1234567890#14#12345678901234567890#0#1234567890#1#1234567890#2#1234567890#3#1234567890#4#1234567890#5#1234567890#6#1234567890#7#1234567890#8#1234567890#9#1234567890#10#1234567890#11#1234567890#12#1234567890#13#1234567890#14#1234567890
I cannot explain the last two communication strings (Fri May 18 17:18:04 2012). Can anyone help me?
For starters, you have clock skew. You're making the assumption that both have exactly the same timing.
For testing, change your python:
import time
import serial
if __name__ == '__main__':
start = time.time()
ser = serial.Serial(port='COM4', baudrate=115200, dsrdtr=True)
while 1:
ser_var=ser.read(210)
print time.asctime()+" "+ser_var
ser.close()
print "serial port close"
Also, are you sure you need dsrdtr enabled? You might just use, "serial.Serial(port='COM4', baudrate=115200)".