We Keep Coding

Problem with python and arduino in pyserial

I wrote this code to print the sensor values ​​in Python, but the problem is that the soil_sensor prints twice.
This is the code in the Arduino :
#include <DHT.h>
#include <DHT_U.h>
#define DHTPIN 8
#define DHTTYPE DHT11
int msensor = A0;
int msvalue = 0;
int min = 0;
int max = 1024;
DHT dht(DHTPIN, DHTTYPE);
void setup() {
Serial.begin(9600);
pinMode(msensor, INPUT);
dht.begin();
}
void loop() {
msvalue = analogRead(msensor);
float percentage = (float)((msvalue - min) * 100) / (max - min);
percentage = map(msvalue, max, min, 0, 100);
Serial.print("r ");Serial.println(percentage);
int h = dht.readHumidity();
int t = dht.readTemperature();
Serial.print ("h ");
Serial.println (h);
Serial.print ("c ");
Serial.println (t);
delay(2000);
}
And this is the code in Python :
from time import sleep
import serial
arduinoP1 = serial.Serial(port="/dev/ttyUSB0", baudrate=9600)
def rtot():
arduino_data = arduinoP1.read(6)
str_rn = arduino_data.decode()
sleep(1)
return str_rn
for x in range(3):
i = rtot()
if "r" in i:
v1 = int(float(i[1:5].strip('\\r\\nr')))
print(v1, 'soil_sensor')
if "c" in i:
print(i[1:2], 'temperature_sensor')
if "h" in i:
v3 = int(i[2:4])
print(v3, 'Humidity_sensor')
As you can see, the soil sensor is repeated twice :
soil sensor is repeated twice
I want the values ​​to be displayed correctly and in the form of numbers

The first thing you should notice is that sending numbers throug the serial interface will result in different string lenghts depending on the number of digits.
So reading a fixed number of 6 bytes is not a good idea. (actually this is almost never a good idea)
You terminate each sensor reading with a linebreak. So why not use readline instead of read[6].
Here v1 = int(float(i[1:5].strip('\\r\\nr'))) you're trying to remove \r, \n and r from the received string. Unfortunately you escaped the backslash so you're actually stripping \, r and n.
\r is actually something where you need the backslash to represent the carriage return character. Don't escape it!
In the first run loop() will send something like:
r 0.00\r\nh 40\r\nc 25\r\n
So the first 6 bytes are r 0.00. So i[1:5] is 0.0.
As you see there is nothing to escape. Also 5 is excluded so you would have to use i[2:6] to get 0.00. But as mentioned above using fixed lenghts for numbers is a bad idea. You can receive anything between 0.00 and 100.00 here.
So using readline you'll receive
r 0.00\r\n
The first and last two characters are always there and we can use [2,-2] to get the number inbetween regardless of its length.

How do I convert float value to string without using sstream for arduino?

I have a DHT11 sensor connected to a Yún shield, and I am reading data from the sensor using DHT library:
indoorHumidity = dhtBedRom.readHumidity();
// Read temperature as Celsius
indorTempinC = dhtBedRom.readTemperature();
// Read temperature as Fahrenheit
indorTempinF = dhtBedRom.readTemperature(true);
// Compute heat index, Must send in temp in Fahrenheit!
hi = dhtBedRom.computeHeatIndex(indorTempinF, indoorHumidity);
hIinCel = (hi + 40) / 1.8 - 40;
dP = (dewPointFast(indorTempinC, indoorHumidity));
dPF = ((dP * 9) / 5) + 32;
and then I am trying to put the data dew point and temperature, humidity and heat index to BridgeClient key so I can read it in a python program that renders HTML and displays using Python's bottle wsgi framework.
These lines produce errors:
Bridge.put(DEWPNTkey, dP);
Bridge.put(HEADINDXkey, hIinCel);
saying:
no matching function for call to 'SerialBridgeClass::put(String&, float&)'

The Bridge.put() method requires a char or a string as its second parameter. So we can use the String constructor to do that.
void setup()
{
Serial.begin(115200); // To test this make sure your serial monitor's baud matches this, or change this to match your serial monitor's baud rate.
double floatVal = 1234.2; // The value we want to convert
// Using String()
String arduinoString = String(floatVal, 4); // 4 is the decimal precision
Serial.print("String(): ");
Serial.println(arduinoString);
// You would use arduinoString now in your Bridge.put() method.
// E.g. Bridge.put("Some Key", arduinoString)
//
// In your case arduinoString would have been dP or hIinCel.
// In case you need it as a char* at some point
char strVal[arduinoString.length() + 1]; // +1 for the null terminator.
arduinoString.toCharArray(strVal, arduinoString.length() + 1);
Serial.print("String() to char*: ");
Serial.println(strVal);
}
void loop()
{
}
And we get:
String(): 1234.2000
String() to char*: 1234.2000
Go here to read about the null terminator.

RaspberryPi to Arduino -send and receive string

This is the code I am currently using to send and receive int values from a RaspberryPi to an Arduino using i2C. It works fine for values 0-255, but because of the 1 byte limit, anything larger fails.
To circumvent this, I'd like to send and receive string values instead, and then convert back to int if necessary.
What changes would I need to make in the following?
Here is my RPi Python code
import smbus
import time
# for RPI version 1, use "bus = smbus.SMBus(0)"
bus = smbus.SMBus(1)
# This is the address we setup in the Arduino Program
address = 0x04
def writeNumber(value):
bus.write_byte(address, value)
# bus.write_byte_data(address, 0, value)
return -1
def readNumber():
number = bus.read_byte(address)
# number = bus.read_byte_data(address, 1)
return number
while True:
try:
var = int(raw_input("Enter 1 - 9: "))
except ValueError:
print "Could you at least give me an actual number?"
continue
writeNumber(var)
print "RPI: Hi Arduino, I sent you ", var
# sleep one second
#time.sleep(1)
number = readNumber()
print "Arduino: Hey RPI, I received a digit ", number
print
And here is my Arduino code
#include <Wire.h>
#define SLAVE_ADDRESS 0x04
int number = 0;
int state = 0;
void setup() {
pinMode(13, OUTPUT);
Serial.begin(9600); // start serial for output
// initialize i2c as slave
Wire.begin(SLAVE_ADDRESS);
// define callbacks for i2c communication
Wire.onReceive(receiveData);
Wire.onRequest(sendData);
Serial.println("Ready!");
}
void loop() {
delay(100);
}
// callback for received data
void receiveData(int byteCount){
while(Wire.available()) {
number = Wire.read();
if (Wire.available() > 1) // at least 2 bytes
{
number = Wire.read() * 256 + Wire.read();
}
Serial.print("data received: ");
Serial.println(number);
//sendData();
if (number == 1){
if (state == 0){
digitalWrite(13, HIGH); // set the LED on
state = 1;
}
else{
digitalWrite(13, LOW); // set the LED off
state = 0;
}
}
}
}
// callback for sending data
void sendData(){
Wire.write(number);
}

This problem essentially has two parts: splitting an integer into its bytes and reassembling an integer from bytes. These parts must be replicated on both the Pi and Arduino. I'll address the Pi side first, in Python:
Splitting an integer:
def writeNumber(value):
# assuming we have an arbitrary size integer passed in value
for character in str(val): # convert into a string and iterate over it
bus.write_byte(address, ord(character)) # send each char's ASCII encoding
return -1
Reassembling an integer from bytes:
def readNumber():
# I'm not familiar with the SMbus library, so you'll have to figure out how to
# tell if any more bytes are available and when a transmission of integer bytes
# is complete. For now, I'll use the boolean variable "bytes_available" to mean
# "we are still transmitting a single value, one byte at a time"
byte_list = []
while bytes_available:
# build list of bytes in an integer - assuming bytes are sent in the same
# order they would be written. Ex: integer '123' is sent as '1', '2', '3'
byte_list.append(bus.read_byte(address))
# now recombine the list of bytes into a single string, then convert back into int
number = int("".join([chr(byte) for byte in byte_list]))
return number
Arduino Side, in C
Split an Integer:
void sendData(){
int i = 0;
String outString = String(number); /* convert integer to string */
int len = outString.length()+1 /* obtain length of string w/ terminator */
char ascii_num[len]; /* create character array */
outString.toCharArray(ascii_num, len); /* copy string to character array */
for (i=0; i<len); ++i){
Wire.write(ascii_num[i]);
}
}
Reassembling a received Integer:
Note: I'm having some trouble understanding what your other code in this routine is doing, so I'm going to reduce it to just assembling the integer.
void receiveData(int byteCount){
int inChar;
String inString = "";
/* As with the Python receive routine, it will be up to you to identify the
terminating condition for this loop - "bytes_available" means the same thing
as before */
while(bytes_available){
inChar = Wire.read();
inString += char(inChar);
}
number = inString.toInt();
}
I don't have the materials on hand to test this, so it's possible I've gotten the byte order flipped in one routine or another. If you find stuff coming in or out backwards, the easiest place to fix it is in the Python script by using the built-in function reversed() on the strings or lists.
References (I used some code from the Arduino Examples):
Arduino String objects
Arduino String Constructors
Python Built-ins chr() and ord()

Check the following Link:
[http://www.i2c-bus.org/][1]
When I was sending data back and forward using I2C I was converting the string characters to bytearrays and viceversa. So since you are always sending bytes. It will always work since you are sending numbers between 0-255.
Not sure this helps but at least may give you an idea.

You could convert the number to a string of digits like you said. But you could also send the raw bytes.
String of digits
Advantages
Number can have infinite digits. Note that when Arduino reads the number as a string, it is infinite, but you can't convert it all to integer if it overflows the 16-bit range (or 32-bit for Due).
Disadvantages
Variable size, thus requiring more effort in reading.
Waste of bytes, because each decimal digit would be a byte, plus the null-terminator totalizing (digits + 1) size.
Having to use decimal arithmetic (which really is only useful for human counting), note that a "number to string" operation also uses decimal arithmetic.
You can't send/receive negative numbers (unless you send the minus signal, wasting more time and bytes).
Raw bytes
Advantages
Number of bytes sent for each integer is always 4.
You can send/receive negative numbers.
The bitwise arithmetic in C++ for extracting each byte from the number is really fast.
Python already has the struct library which packs/unpacks each byte in a number to a string to send/receive, so you don't need to do the arithmetic like in C++.
Disadvantages
Number has a limited range (signed 32-bit integer in our case, which ranges from -2147483648 to 2147483647). But it doesn't matter because no Arduino can handle more than 32-bit anyways.
So I would use the raw bytes method, which I can provide some untested functions here:
import struct
# '<i' stands for litle-endian signed integer
def writeNumber(value):
strout = struct.pack('<i', value)
for i in range(4):
bus.write_byte(address, strout[i])
return -1
def readNumber():
strin = ""
for _ in range(4):
strin += bus.read_byte(address)
return struct.unpack('<i', strin)[0]
And the Arduino part:
void receiveData(int byteCount)
{
// Check if we have a 32-bit number (4 bytes) in queue
while(Wire.available() >= 4)
{
number = 0;
for(int i = 0; i < 32; i += 8)
{
// This is merging the bytes into a single integer
number |= ((int)Wire.read() << i);
}
Serial.print("data received: ");
Serial.println(number);
// ...
}
}
void sendData()
{
for(int i = 0; i < 32; i += 8)
{
// This is extracting each byte from the number
Wire.write((number >> i) & 0xFF);
}
}
I don't have any experience with I2C, but if its queue is a FIFO, then the code should work.

Writing data to arduino python

I'm trying to write data from python to serial with this sketch
import serial
import smtplib
import time
s=serial.Serial('/dev/tty.usbserial-AH01LLHS',9600)
precx=500
ist=30
i=0
while True:
s.write('1')
stringa=s.readline()
array=stringa.split(',')
x=int(array[0])
y=int(array[1])
z=int(array[2])
print(x,y,z)
if(precx!=500):
diffx=abs(x-precx)
diffy=abs(y-precy)
diffz=abs(z-precz)
if((diffx>ist)|(diffy>ist)|(diffz>ist)):
print('Ohu god',i)
i+=1
#time.sleep(2)
precx=x
precy=y
precz=z
But when I execute the program I see nothing on the console, and the Arduino Rx led is off.
This is my Arduino sketch (nano atmega 328):
//Add the SPI library so we can communicate with the ADXL345 sensor
#include <SPI.h>
//Assign the Chip Select signal to pin 10.
int CS=10;
//This is a list of some of the registers available on the ADXL345.
//To learn more about these and the rest of the registers on the ADXL345, read the datasheet!
char POWER_CTL = 0x2D; //Power Control Register
char DATA_FORMAT = 0x31;
char DATAX0 = 0x32; //X-Axis Data 0
char DATAX1 = 0x33; //X-Axis Data 1
char DATAY0 = 0x34; //Y-Axis Data 0
char DATAY1 = 0x35; //Y-Axis Data 1
char DATAZ0 = 0x36; //Z-Axis Data 0
char DATAZ1 = 0x37; //Z-Axis Data 1
//This buffer will hold values read from the ADXL345 registers.
char values[10];
//These variables will be used to hold the x,y and z axis accelerometer values.
int x,y,z;
boolean snd;
void setup(){
//Initiate an SPI communication instance.
SPI.begin();
//Configure the SPI connection for the ADXL345.
SPI.setDataMode(SPI_MODE3);
//Create a serial connection to display the data on the terminal.
Serial.begin(9600);
//Set up the Chip Select pin to be an output from the Arduino.
pinMode(CS, OUTPUT);
//Before communication starts, the Chip Select pin needs to be set high.
digitalWrite(CS, HIGH);
//Put the ADXL345 into +/- 4G range by writing the value 0x01 to the DATA_FORMAT register.
writeRegister(DATA_FORMAT, 0x01);
//Put the ADXL345 into Measurement Mode by writing 0x08 to the POWER_CTL register.
writeRegister(POWER_CTL, 0x08); //Measurement mode
}
void loop(){
//snd=true;
//Reading 6 bytes of data starting at register DATAX0 will retrieve the x,y and z acceleration values from the ADXL345.
//The results of the read operation will get stored to the values[] buffer.
readRegister(DATAX0, 6, values);
//The ADXL345 gives 10-bit acceleration values, but they are stored as bytes (8-bits). To get the full value, two bytes must be combined for each axis.
//The X value is stored in values[0] and values[1].
x = ((int)values[1]<<8)|(int)values[0];
//The Y value is stored in values[2] and values[3].
y = ((int)values[3]<<8)|(int)values[2];
//The Z value is stored in values[4] and values[5].
z = ((int)values[5]<<8)|(int)values[4];
if (Serial.available() > 0) {
if(Serial.read()=='1'){
snd=true;
}
else{
snd=false;
}
}
if(snd){
//Print the results to the terminal.
Serial.print(x, DEC);
Serial.print(',');
Serial.print(y, DEC);
Serial.print(',');
Serial.print(z, DEC);
Serial.println("");
delay(10);
}
}
//This function will write a value to a register on the ADXL345.
//Parameters:
// char registerAddress - The register to write a value to
// char value - The value to be written to the specified register.
void writeRegister(char registerAddress, char value){
//Set Chip Select pin low to signal the beginning of an SPI packet.
digitalWrite(CS, LOW);
//Transfer the register address over SPI.
SPI.transfer(registerAddress);
//Transfer the desired register value over SPI.
SPI.transfer(value);
//Set the Chip Select pin high to signal the end of an SPI packet.
digitalWrite(CS, HIGH);
}
//This function will read a certain number of registers starting from a specified address and store their values in a buffer.
//Parameters:
// char registerAddress - The register addresse to start the read sequence from.
// int numBytes - The number of registers that should be read.
// char * values - A pointer to a buffer where the results of the operation should be stored.
void readRegister(char registerAddress, int numBytes, char * values){
//Since we're performing a read operation, the most significant bit of the register address should be set.
char address = 0x80 | registerAddress;
//If we're doing a multi-byte read, bit 6 needs to be set as well.
if(numBytes > 1)address = address | 0x40;
//Set the Chip select pin low to start an SPI packet.
digitalWrite(CS, LOW);
//Transfer the starting register address that needs to be read.
SPI.transfer(address);
//Continue to read registers until we've read the number specified, storing the results to the input buffer.
for(int i=0; i<numBytes; i++){
values[i] = SPI.transfer(0x00);
}
//Set the Chips Select pin high to end the SPI packet.
digitalWrite(CS, HIGH);
}
Thanks in advance.

You should definitely check the suggestions from the comments:
make the program simpler so that it always sends values without "flow control" (using the "1" byte you send),
use a serial monitor to check the output.
First, you shall check if you add a s.flush() before and after your s.write('1') helps. Then you may want to add flush() in your arduino code too.
To me it really looks like a starving issue at the initialization of your "flow control" algorithm. On the paper it looks good, but in real life, it may not. Very often, the Arduino sends a lot of garbage when it starts filling up the host serial port's buffer. And the other way around may be true. So instead of having a 1 on the arduino side, you may get a !##$##%##%!##$ that's totally useless.
So on either side, before getting in the loops, you should add an init protocol. The arduino sends READY, the host sends READY, you flush out everything until you get READY on both sides. Something that would look like:
void setup() {
Serial.begin(9600);
Serial.println('READY');
Serial.flush();
char ch1 = 0, ch2 = 0;
char incomingByte = 0;
while (ch1 != 'O' && ch2 != 'K') {
ch1 = Serial.read();
if (ch1 == 'O' && ch2 == 'K')
break;
ch2 = Serial.read();
}
}
and on the python side:
with serial.Serial('/dev/tty.usbserial-AH01LLHS',9600) as s:
s.flush()
ready = ""
while ready != "READY":
ready = s.readline()
s.flush()
while True:
# ... you stuff
of course that's only an idea of what you may do. You can make it more sophisticated, or way more simple. But before making such flow control, you really need to create a meeting point.

Sending integer values to Arduino from PySerial

I need to send integers greater than 255? Does anyone know how to do this?

Here's how (Thanks for the idea, Alex!):
Python:
def packIntegerAsULong(value):
"""Packs a python 4 byte unsigned integer to an arduino unsigned long"""
return struct.pack('I', value) #should check bounds
# To see what it looks like on python side
val = 15000
print binascii.hexlify(port.packIntegerAsULong(val))
# send and receive via pyserial
ser = serial.Serial(serialport, bps, timeout=1)
ser.write(packIntegerAsULong(val))
line = ser.readLine()
print line
Arduino:
unsigned long readULongFromBytes() {
union u_tag {
byte b[4];
unsigned long ulval;
} u;
u.b[0] = Serial.read();
u.b[1] = Serial.read();
u.b[2] = Serial.read();
u.b[3] = Serial.read();
return u.ulval;
}
unsigned long val = readULongFromBytes();
Serial.print(val, DEC); // send to python to check

Encode them into binary strings with Python's struct module. I don't know if arduino wants them little-endian or big-endian, but, if its docs aren't clear about this, a little experiment should easily settle the question;-).

Way easier :
crc_out = binascii.crc32(data_out) & 0xffffffff # create unsigned long
print "crc bytes written",arduino.write(struct.pack('<L', crc_out)) #L, I whatever u like to use just use 4 bytes value
unsigned long crc_python = 0;
for(uint8_t i=0;i<4;i++){
crc_python |= ((long) Serial.read() << (i*8));
}
No union needed and short !