I'm trying to send a set of [x, y] coordinates from python to arduino in order to control servo motors on a robot drivetrain. I'm taking the approach of sending a string in the format "x,y". On the arduino side, I'm trying to parse this string to get the x and y substrings. However the indexOf function doesn't return the proper index. Here is my code:
arduino = serial.Serial(port='COM3', baudrate=9600, timeout=.1)
def write_read(x):
arduino.write(bytes(x, 'utf-8'))
time.sleep(0.05)
data = arduino.readline()
return data
for coordinate in coordinates:
c = str(coordinate[0]) + ", " + str(coordinate[1])
print(write_read(c))
#include <Servo.h>
void setup() {
Serial.begin(9600);
Serial.setTimeout(1);
}
void loop() {
while (!Serial.available());
String coordinates = "" + Serial.readString();
// Serial.print(coordinates); //this prints normally as the string value
int i = coordinates.indexOf(',');
Serial.print(i);
}
When I send something like "-9.45, -16.3". The output is b'-1-1-1-1-10-1-1-1-1-1-1'. I'm not sure what's going on here or how to get the actual index (in this case it would be 5).
Related
Good Day! I was struggling about my arduino MLX90614 code my pyserial cant read the data it show's
Here's my arduino MLX90614 code:
#include <Wire.h>
#include <Adafruit_MLX90614.h>
Adafruit_MLX90614 mlx = Adafruit_MLX90614();
void setup() {
Serial.begin(9600);
mlx.begin();
}
void loop() {
Serial.print("Ambient = "); Serial.print(mlx.readAmbientTempC());
Serial.print("*C\tObject = "); Serial.print(mlx.readObjectTempC()); Serial.println("*C");
Serial.print("Ambient = "); Serial.print(mlx.readAmbientTempF());
Serial.print("*F\tObject = "); Serial.print(mlx.readObjectTempF()); Serial.println("*F");
Serial.println();
delay(500);
}
And heres my python code "Pyserial" to read the data from my arduino
import csv
from time import time
import serial
# Your serial port might be different!
ser = serial.Serial('COM5', timeout=1)
f = open("df.csv", "a+")
writer = csv.writer(f, delimiter=',')
while True:
s = ser.readline().decode()
if s != "":
rows = [float(x) for x in s.split(',')]
# Insert local time to list's first position
rows.insert(0, int(time()))
print(rows)
writer.writerow(rows)
f.flush()
But in result it show's this
"rows = [float(x) for x in s.split(',')]
ValueError: could not convert string to float: 'Ambient 30c /n'"
Someone please help me with this I am really struggling with connecting my Arduino MLX90614 to my Arduino. Thanks in advance
If s != '' is not a space, add the whitespace between the quotes, this is returning values that cannot be passed to the int constructor.
Comment the list comprehension out and print instead to see the current values your code is storing.
import serial
ser= serial.Serial('com5',9600)
while 1:
Value_from_arduino = ser.readline()
Zustand = float(Value_from_arduino)
print(Zustand)
if Zustand == 1:
ser.write(0)
print('off')
elif Zustand == 0:
ser.write(1)
print(on)
This was the Python code, now here the arduino code.
char serialData;
int pin=12;
int pin2 = 5;
int Value;
void setup(){
pinMode(pin,OUTPUT);
pinMode(pin2,INPUT);
Serial.begin(9600);
}
void loop(){
Value = digitalRead(pin2);
Serial.println(Value);
delay(250);
while(Serial.available()){
serialData = Serial.read();
Serial.print(serialData);
if(serialData = '1'){
digitalWrite(pin,HIGH);
}
else if(serialData = '0'){
digitalWrite(pin,LOW);
}
}
}
My problem is, when i run my python code, it stops when he gets the Value 0 from my arduino.
Here is the report from python:
Zustand = float(Value_from_Arduino)
ValueError: could not convert string to float: b'\x000\r\n'
Python immediatly stops, but he puts the LED on.
The LED should be on if Python gets the value of 0, he do but then he just end run.
The LED should go on if value is 0 and of if value is 1.
You need to decode the serial bytes from the serial port.
Replace the Zustand = line in your code
Value_from_arduino = ser.readline()
Zustand = float(ser_bytes[0:len(Value_from_arduino )-2].decode("utf-8"))
Please check here https://makersportal.com/blog/2018/2/25/python-datalogger-reading-the-serial-output-from-arduino-to-analyze-data-using-pyserial
also try, if encodings doesn't work well
import struct
Zustand, = struct.unpack('<f',Value_from_arduino )
Finally i have found out please replace these lines of code
Steps -> Read,Decode to string, Strip /n and /r, Convert to float
please check here https://problemsolvingwithpython.com/11-Python-and-External-Hardware/11.04-Reading-a-Sensor-with-Python/
Value_from_arduino = ser.readline()
Value_from_arduino = Value_from_arduino.decode()
Value_from_arduino = Value_from_arduino.rstrip()
Zustand = float(Value_from_arduino)
Hope this Works..
In a project of mine, I have to take a picture from a camera connected to a Sony Spresense Arduino board which is linked to my computer via an USB port. I am not very experienced in Arduino and serial communication, not at all in fact, so I am asking for some help.
I want to read the data from the camera which is sent in hexadecimal from the Arduino to my computer via a Serial.begin at a given baud rate, processed by a Python program in order to collect the hex code, correct it (there have been some print errors which are now solved), and convert it to a JPEG image.
I am able to do it, but the serial communication part of my program where Python collects the data from the Arduino is significantly slow, it takes 34 seconds to obtain an image that weighs "only" 100 ko (I don't know if it's a lot to handle for an Arduino), at a baud rate of 115200. If I try to increase this number, the hex code collected shows some errors and the image can not be converted. I can also change the pixel resolution of the image, but I'd like to be able to work with HD pictures.
In detail, here is the code from the Arduino, I have found no other way than this to get the data from the camera (there is no designed function in the Spresense library for serial communication). The relevant part is at the end :
#include <SDHCI.h>
#include <stdio.h> /* for sprintf */
#include <Camera.h>
#define BAUDRATE (115200)
/**
* Print error message
*/
void printError(enum CamErr err)
{
Serial.print("Error: ");
switch (err)
{
case CAM_ERR_NO_DEVICE:
Serial.println("No Device");
break;
case CAM_ERR_ILLEGAL_DEVERR:
Serial.println("Illegal device error");
break;
case CAM_ERR_ALREADY_INITIALIZED:
Serial.println("Already initialized");
break;
case CAM_ERR_NOT_INITIALIZED:
Serial.println("Not initialized");
break;
case CAM_ERR_NOT_STILL_INITIALIZED:
Serial.println("Still picture not initialized");
break;
case CAM_ERR_CANT_CREATE_THREAD:
Serial.println("Failed to create thread");
break;
case CAM_ERR_INVALID_PARAM:
Serial.println("Invalid parameter");
break;
case CAM_ERR_NO_MEMORY:
Serial.println("No memory");
break;
case CAM_ERR_USR_INUSED:
Serial.println("Buffer already in use");
break;
case CAM_ERR_NOT_PERMITTED:
Serial.println("Operation not permitted");
break;
default:
break;
}
}
void CamCB(CamImage img)
{
/* Check the img instance is available or not. */
if (img.isAvailable())
{
/* If you want RGB565 data, convert image data format to RGB565 */
img.convertPixFormat(CAM_IMAGE_PIX_FMT_RGB565);
}
else
{
Serial.print("Failed to get video stream image\n");
}
}
/**
* #brief Initialize camera
*/
void setup()
{
CamErr err;
/* Open serial communications and wait for port to open */
Serial.begin(BAUDRATE);
while (!Serial)
{
; /* wait for serial port to connect. Needed for native USB port only */
}
/* begin() without parameters means that
* number of buffers = 1, 30FPS, QVGA, YUV 4:2:2 format */
Serial.println("Prepare camera");
err = theCamera.begin();
if (err != CAM_ERR_SUCCESS)
{
printError(err);
}
/* Start video stream.
* If received video stream data from camera device,
* camera library call CamCB.
*/
Serial.println("Start streaming");
err = theCamera.startStreaming(true, CamCB);
if (err != CAM_ERR_SUCCESS)
{
printError(err);
}
/* Auto white balance configuration */
// Serial.println("Set Auto white balance parameter");
err = theCamera.setAutoWhiteBalanceMode(CAM_WHITE_BALANCE_DAYLIGHT);
if (err != CAM_ERR_SUCCESS)
{
printError(err);
}
/* Set parameters about still picture.
* In the following case, QUADVGA and JPEG.
*/
Serial.println("Set still picture format");
// err = theCamera.setStillPictureImageFormat(
// CAM_IMGSIZE_QUADVGA_H,
// CAM_IMGSIZE_QUADVGA_V,
// CAM_IMAGE_PIX_FMT_JPG);
//err = theCamera.setStillPictureImageFormat(320, 240, CAM_IMAGE_PIX_FMT_JPG);
err = theCamera.setStillPictureImageFormat(CAM_IMGSIZE_QUADVGA_H, CAM_IMGSIZE_QUADVGA_V, CAM_IMAGE_PIX_FMT_JPG);
if (err != CAM_ERR_SUCCESS)
{
printError(err);
}
/**
* #brief Take picture with format JPEG per second
*/
/******** Affichage serie ********/
/* une ligne de vide et l'image */
Serial.println(" ");
CamImage img = theCamera.takePicture();
/* Check availability of the img instance. */
/* If any error was occured, the img is not available. */
if (img.isAvailable())
{
/*Indicateur de debut img : FFD8FF (Magic number of the jpeg format) */
for(int i=0;i<img.getImgSize();i++)
{
Serial.print(*(img.getImgBuff()+i),HEX); //img.getImgBuff() gets the data address of the picture, so the * before.
Serial.print(";");
}
/*End indicator : FFD9FF (Magic number of jpeg format) */
}
}
void loop()
{
// put your main code here, to run repeatedly:
sleep(1);
}
And here is the Python code :
## Serial collecting the data of the picture taken by the camera
import serial
from serial import Serial
import binascii
import string
from PIL import Image
import time
start_time = time.time()
ser = serial.Serial('COM3', baudrate=115200, timeout=1)
# writing the data in a text file
data = open("data.txt", "w")
data.write(str(ser.readlines()))
## Correcting the data
data = open("data.txt", "r")
string = str(data.readlines())
# spliting the string into a list
# I chose to use the ";" to split the different hex couples in the Arduino program
tab=string.split(";")
tab[0] = 'FF'
tab.pop(-1)
N = len(tab)
# correcting the arguments that are not couples :
# Indeed, when Arduino encounter a couple starting with a 0,
# it omits it, so I have to add it back manually
for i in range(N):
if len(tab[i]) == 1:
tab[i] = '0' + tab[i]
newdata = open("newdata.txt", "w")
# writing the new data in a text file
for s in tab:
newdata.write(s)
newdata.close()
data.close()
## Converting the hex data into a JPEG file
file = open("newdata.txt", "r")
data= file.read()
# conversion
data = binascii.a2b_hex(data)
# creation of the JPEG file
with open('imagenew.jpg', 'wb') as image_file:
image_file.write(data)
file.close()
img = Image.open('imagenew.jpg')
img.show()
print("--- %s seconds ---" % (time.time() - start_time))
If you have any idea or any advice in order to speed up this process I am taking it. I heard that there are some flow control and buffer stories here and there, but I am quite lost when I try to find something relevant to my situation. Thanks in advance.
I need to read 2 different bytes from TTP229 (16 keys or 8 keys touch pad detector).
I use I2C In Python. TTP229 datasheet PDF.
I can't read the second byte, but I can get the first byte.
Python code:
import smbus
bus = smbus.SMBus(1)
adressTTP229 = 0x57 #0xAF>>1
byte1 = bus.read_byte(adressTTP229)
byte2 = bus.read_byte(adressTTP229)
byte1 is always equal to byte2.
This Arduino code, works ok:
#include <Wire.h>
#define ttp229 (0xAF>>1)
void setup() {
Serial.begin(9600); // start serial for output
Wire.begin();
}
void loop() {
delay(50);
bool isNewData = false;
Wire.requestFrom(ttp229,2,true);
while (Wire.available()) {
uint16_t b1 = Wire.read(); // receive a first byte
uint16_t b2 = Wire.read(); // receive a second byte
if (b1==b2 && b2==0) {break;}
//...
}
}
How do I use Arduino's requestFrom() function in Python?
try:
import smbus, time
bus = smbus.SMBus(1)
while True:
print bus.read_word(0xAF)
time.sleep(0.1)
dont change address, bus doe the conversion, and if you read byte you will always get the same first byte. you want to read a word = 2 bytes at once
not tested, but might work, have it ordered and will test
I have encountered an error that has been seriously bothering me, and I have been unable to find a workaround. I have a python program that utilizes PySerial to import serial port values from a pulse oximeter. The problem is, when the function ser.readline() is invoked (in other words, when the python program is told to read values from the Arduino's serial monitor, the Arduino's serial values become distorted and the program returns a value unpack error.
Here is the python program.
import serial
import time
import pylab
import matplotlib.pyplot as plt
import numpy as np
import os
import csv
#time load
timestr = time.strftime("%Y_%m_%d")
#establish serial connection with ACM0
ser = serial.Serial('/dev/ttyACM0', 115200)
#establish variables
thymeL = [ ]
bpmL = [ ]
sp02L = [ ]
array_data = thymeL, bpmL, sp02L
#declare time
thyme = 1
#graph attributes
plt.ion()
plt.title("Pulse [BPM] & SPo2 [%] v. Time [s]", fontsize = "16")
plt.xlabel("Time [s]", fontsize = "14")
plt.ylabel("Pulse (red) [BPM] & SPo2 (blue) [%]", fontsize = "14")
while True:
data_in = ser.readline()
print data_in
data_in = data_in.strip('\n')
bpm,sp02 = data_in.split(",")
#convert string vals to float
thyme = float(thyme)
bpm = float(bpm)
sp02 = float(sp02)
#print to terminal
print "Time [s]: %s" % (thyme)
print "HR [BPM]: %s" % (bpm)
print "SPO2 [%%]: %s" % (sp02)
print
#append vectors
thymeL.append(thyme)
bpmL.append(bpm)
sp02L.append(sp02)
#print values to plot
plt.scatter(thyme,bpm,color="red")
plt.scatter(thyme,sp02,color="blue")
plt.pause(0.1)
time.sleep(0.05)
#update time
thyme = thyme + 0.5
#write to .csv
with open(full_path, 'w') as f:
writer = csv.writer(f)
for t, b, s in zip(array_data[0], array_data[1], array_data[2]):
writer.writerow([t, b, s])
The most important snippet of all is:
while True:
data_in = ser.readline()
print data_in
data_in = data_in.strip('\n')
bpm,sp02 = data_in.split(",")
The Arduino program is as follows:
#include <PinChangeInt.h>
#include <eHealth.h>
int cont = 0;
void setup() {
Serial.begin(115200);
eHealth.initPulsioximeter();
PCintPort::attachInterrupt(6, readPulsioximeter, RISING);
}
void loop() {
char buffer[32]; // make sure buffer is large enough
sprintf(buffer,"%d,%d \n",eHealth.getBPM(),eHealth.getOxygenSaturation());
Serial.print(buffer);
delay(500);
}
//=========================================================================
void readPulsioximeter(){
cont ++;
if (cont == 50) { //Get only of one 50 measures to reduce the latency
eHealth.readPulsioximeter();
cont = 0;
}
}
So, the serial monitor is outputting values like this:
67,95
66,95
67,96
and so on.
But only when ser.readline() is invoked, the values become skewed and are unable to be unpacked by the split(',') function. In the following photo (1) and (2), you can see the distortion of the values right when the ser.readline() is called.
How can I re-word the python OR Arduino program in such a way to circumvent this distortion and allow the values to be split and unpacked without any errors?
So is there any possibility that something else is calling loop() asynchronously, e.g. from an interrupt routine, which might try to simultaneously transmit another string of readings at the same time as the arduino's 'mainline' calling of the loop function? An aside: if the interrupt routine readPulsioximeter() got invoked while the mainline loop() function was between the calls to eHealth.getBPM() and eHealth.getOxygenSaturation() and updated the Pulsioximeter attributes, does your code guarantee to send values from the same reading out onto the serial port?