I want to send multibyte integers,(eg. 1000,10000, etc) from raspberry pi to arduino. It can either be in the form of int or string(will convert it into integer on arduino's side) through i2c. Now, I am able to send data but only till 255, If I try to send 1000, the output on ARduino serial terminal will be 232 and not 1000. I tried to search over the internet for like 4-5 hours, but no luck. Can someone please guide me?
import smbus
import time
bus = smbus.SMBus(1)
address = 0x04
a=1000
#a=str(a)
def writeString(a,b,c,d):
bus.write_i2c_block_data(address, a, [b, c, d])
return -1
while True:
try:
writeString(1000,a,5,0)
time.sleep(1) #delay one second
except KeyboardInterrupt:
quit()
Arduino:
#include <Wire.h>
int data [4];
int x = 0;
void setup() {
Serial.begin(9600);
Wire.begin(0x04);
Wire.onReceive(receiveData); //callback for i2c. Jump to void recieveData() function when pi sends data
}
void loop () {
delay(100); //Delay 0.1 seconds. Something for the arduino to do when it is not inside the reciveData() function. This also might be to prevent data collisions.
}
void receiveData(int byteCount) {
while(Wire.available()) { //Wire.available() returns the number of bytes available for retrieval with Wire.read(). Or it returns TRUE for values >0.
data[x]=Wire.read();
x++;
}
Serial.println("----");
Serial.print(data[0]);
Serial.print("\t");
Serial.print(data[1]);
Serial.print("\t");
Serial.print(data[2]);
Serial.print("\t");
Serial.println(data[3]);
// Serial.print("----");
}
I2C sends and receives BYTES. 1000 in hex is 0x3E8. 232 in hex is 0xE8. Only the low byte is sent.
Related
I'm using an app to either turn on an LED or change the angle of a micro servo depending on which button is pressed (using Arduino). My code works for the LED (while the button is pressed, the LED is on) but nothing happens when I press the button meant to change the angle of the servo to 40.
// Bluetooth serial:
#include <SoftwareSerial.h> // import the serial library
// setup the bluetooth coms
SoftwareSerial BTSerial(8,7);
#include <Servo.h>
int servoPin = 0;
Servo servo;
int angle = 0; // servo position in degrees
int input = 0;
int led2 = 13;
void setup() {
// put your setup code here, to run once:
servo.attach(servoPin);
Serial.begin(9600); // coms w/ computer
BTSerial.begin(9600); // coms w/ Bluetooth
pinMode(led2, OUTPUT);
}
void loop() {
// put your main code here, to run repeatedly:
if (BTSerial.available())
{
input = BTSerial.read();
digitalWrite(led2, LOW);
switch(input) {
case 'E':
angle = 40;
break;
case 'C':
digitalWrite(led2, HIGH);
break;
}
servo.write(angle);
}
}
The input is right as I checked by also turning the LED on in case 'E' where it worked as normal. I had also tried using servo.write() within the case function as well but this didn't work either.
case 'E':
servo.write(40);
break;
You cannot use digital pins 0 or 1 as input:
As mentioned, those are serial send and receive pins. If you power your computer through USB, it can interfere if you try to use them, since it's reading from both the USB to Serial and the pin. Also you have an issue with anything connected (well, not anything, but remove it just to be safe) when you're trying to program. If you use the pins as intended, and program then run it off battery, it should be no problem at all.
Most of us stay away from it because it's a bit of a hassle
Depending on your Arduino model, servo.attach only supports pins 9 and 10:
Note that in Arduino 0016 and earlier, the Servo library supports only servos on only two pins: 9 and 10.
Or you could just use one of those anyway.
I am having trouble with the arduino sound sensor and LEDs. I keep on getting the value of 0 in my serial monitor, the same thing happens with another sound sensor that I have. I am currently trying to make it light up the LEDs based on the sound but with the serial monitor reading 0 it will not activate the code. There should be a picture attached. The lights on the sound sensor is lighting up so I know the GND and 5V is working. Since it is hard to tell I am using 330 ohm resisters. I got the sound sensor from an elegoo starter kit, so I know it might be cheap. The picture is in the link at the end. Thank you.
int MicPin = A0;
int MicValue1 = 0;
int MicValue2 = 0;
int led1 = 2;
int led2 = 4;
int led3 = 6;
int led4 = 8;
void setup() {
pinMode(led1, OUTPUT);
pinMode(led2, OUTPUT);
pinMode(led3, OUTPUT);
pinMode(led4, OUTPUT);
pinMode(MicPin, OUTPUT);
Serial.begin(9600);
}
void loop() {
MicValue1 = analogRead(MicPin);
Serial.println(MicValue1);
delay(1);
MicValue2 = analogRead(MicPin);
Serial.println(MicValue2);
if (MicValue1 - MicValue2 > 1) {
digitalWrite(led1, HIGH);
delay(2000);
}
else {
digitalWrite(led1, LOW);
}
}
enter image description here
I assume that you have a simple analog-output sensor module that provides 10bit analog values based on the environment volume level. If this assumption is correct, you wired all pins correctly and the received value is always out of range or at the maximum, you maybe had to integrate a resistor to get a valid value. Try a small resistor and increase the resistance until you receive suitable values. Maybe the documentation of your module provides further information.
There is a small rotating knob connected to the sensor on which we need to rotate to adjust particular resistance values, you can see different values in serial monitor out.
Useful link
I am experimenting with connecting Raspberry Pi to Arduino, and when I set a loop to receive info from Arduino Uno serial, it only receives:
'118537\r\n'
That is when I try to serial print 'Hi'
Here is my arduino code:
void setup(){
Serial.begin(9600);
}
void loop(){
Serial.println('Hi');
delay(2000);
}
Here is my python 3.2 code:
import serial
ser = serial.Serial('/dev/ttyACM0')
while True:
print(ser.readline())
This prints: '118537\r\n' every 2 seconds.
How can I get the original 'Hi' every 2 seconds?
For those of you who want to know, it was the fact that I used ' instead of " in the string, changing:
Serial.println('Hi');
to
Serial.println("Hi");
eta: the reason why '118537\n\n' is printed out is because 'Hi' is a literal array of two bytes rather than a "string" and therefore the compiler uses the function for printing an int. In fact, the hex code of H is 48 and the hex code of i is 69, and the hexadecimal value of 0x4869 is exactly 118537 in decimal notation.
I'm trying to talk to an arduino via a rs485 serial link. I have a usb to serial rs485 adapter plugged in my pc and a max485 in the arduino side. To get started i simply uploaded a sketch that send back what it receives.
#include <SoftwareSerial.h>
#define SSerialRX 10 //Serial Receive pin
#define SSerialTX 11 //Serial Transmit pin
#define SSerialTxControl 3 //RS485 Direction control
#define RS485Transmit HIGH
#define RS485Receive LOW
#define Pin13LED 13
SoftwareSerial RS485Serial(SSerialRX, SSerialTX); // RX, TX
void setup()
{
pinMode(Pin13LED, OUTPUT);
pinMode(SSerialTxControl, OUTPUT);
digitalWrite(SSerialTxControl, RS485Receive);
RS485Serial.begin(300);
}//--(end setup )---
void loop()
{
if (RS485Serial.available()){
delay(100);
char x = RS485Serial.read();
digitalWrite(Pin13LED, HIGH);
digitalWrite(SSerialTxControl, RS485Transmit); // Enable RS485 Transmit
Serial.write(x);
RS485Serial.write(x);
Serial.flush();
delay(10);
digitalWrite(SSerialTxControl, RS485Receive); // Disable RS485 Transmit
digitalWrite(Pin13LED, LOW);
delay(200);
}
}//--(end main loop )---
Then, to test the connection, i run a python script in the pc that writes a character to the serial port and listens to the response:
import serial
import time
PORT1 = "/dev/ttyUSB0"
try:
rs485 = serial.Serial(PORT1, 300)
while True:
print 'loop'
rs485.write('r')
time.sleep(0.5)
data = rs485.read()
if data == '\0':
print 'null'
else:
print data
time.sleep(1)
except:
rs485.close()
The first time I launch the script it happens something like this:
giulio#giulio-vaio:~$ python rs485io.py
loop
r
loop
r
loop
^C
If i try to launch again the script, it writes nothing more than:
giulio#giulio-vaio:~$ python rs485io.py
loop
null
loop
null
loop
null
^C
It starts working again only if i reboot my pc (with ubuntu by the way). If i unplug and plug again the usb to serial converter, nothing changes, if i reboot the arduino, same story. I tried the same configuration with a raspberry pi and the result is identical. Changing usb port doesn't work, upload again the same sketch in the arduino, nothing happens.
The led on the pin 13 blinks, so the arduino is receiving and sending something, the serial.read() function returns, so something is arriving, but is (after the first time) a null carachter '\x00'. In one positive case, after rebooting, I tried to let the script go on for a few time and everything went fine, until i hitted ctrl-c and started again the script.
This is dmesg after i plug in the serial converter:
[ 6116.508264] usb 1-2.1.3: new full-speed USB device number 27 using ehci-pci
[ 6116.617247] usb 1-2.1.3: New USB device found, idVendor=1a86, idProduct=7523
[ 6116.617257] usb 1-2.1.3: New USB device strings: Mfr=0, Product=2, SerialNumber=0
[ 6116.617264] usb 1-2.1.3: Product: USB2.0-Serial
[ 6116.617694] ch341 1-2.1.3:1.0: ch341-uart converter detected
[ 6116.621498] usb 1-2.1.3: ch341-uart converter now attached to ttyUSB0
I don't know what to do after this, any help would be appreciated.
EDIT :
the pc doesn't need to be rebooted, it works if i unload and then load again the module ch341, the one that handles the usb converter.
I added two lines at the top of the code:
subprocess.Popen("modprobe -r ch341".split()).wait()
subprocess.Popen("modprobe ch341".split()).wait()
I know it doesn't really solve the problem, but it works.
EDIT 2 :
Looking at the documentation http://lxr.free-electrons.com/source/Documentation/serial/serial-rs485.txt , I tried to send an ioctl signal to the driver, using this code in c (i'm not good with C, so please forgive me)
#include (all the libraries needed)
/* Driver-specific ioctls: */
#define TIOCGRS485 0x542E
#define TIOCSRS485 0x542F
/* Open your specific device (e.g., /dev/mydevice): */
int main(){
const char *file1 = "/dev/ttyUSB0";
const char *file2 = "output_cprog.txt";
int fd = open (file1,O_WRONLY);
if(fd < 0){
printf("%s: %s\n","error opening ttyusb",strerror( errno ) );
}
int fq = open(file2,O_WRONLY);
if( fq < 0){
printf("%s: %s\n","errore apertura file",strerror( errno ));
}
struct serial_rs485 rs485conf;
// Enable RS485 mode:
rs485conf.flags |= SER_RS485_ENABLED;
// Set logical level for RTS pin equal to 1 when sending:
rs485conf.flags |= SER_RS485_RTS_ON_SEND;
// or, set logical level for RTS pin equal to 0 after sending:
rs485conf.flags &= ~(SER_RS485_RTS_AFTER_SEND);
// Set rts delay before send, if needed:
rs485conf.delay_rts_before_send = 10;
// Set rts delay after send, if needed:
rs485conf.delay_rts_after_send = 10;
int ioc = ioctl (fd, TIOCSRS485, &rs485conf);
if(ioc < 0){
printf("%i\n",ioc);
printf("ioctl error: %s\n", strerror( errno ));
}
char *character = "f\n";
write(fd,character,2);
char *buffer;
buffer = (char *) malloc(10);
read(fd, buffer, 1);
write(fq, buffer, 1);
printf("received character: %s\n",buffer[0]);
if( close(fd) < 0){
printf("%s: %s\n","error closing port",strerror( errno ));
}
if (close(fq) < 0){
printf("%s: %s\n","error closing file",strerror( errno ));
}
return 0;
}
but compiling and running the program what i see is only this:
giulio#giulio-vaio:~$ ./ioctlRS485.o
-1
ioctl error: Inappropriate ioctl for device
received character: (null)
I think, by looking at the driver https://github.com/torvalds/linux/blob/master/drivers/usb/serial/ch341.c that it doesn't have the appropriate function to handle an ioctl at all.
to start off, this might not be a problem with arduino code or arduino, but I figured I would post here because I really just can not figure out what is wrong.
I am working on this project just for fun to send key strokes from the keyboard, through the computer, and out through the USB to my arduino mega. No additional hardware is here, just the computer, the arduino, and the USB cable.
I am using Microsoft Visual Studio Express 2012 to write code to receive key strokes and send them to the USB. This is the code I am using:
#include "stdafx.h"
#include "conio.h"
using namespace System;
using namespace System::IO::Ports;
int main(array<System::String ^> ^args)
{
String^ portName;
String^ key;
int baudRate=9600;
Console::WriteLine("type in a port name and hit ENTER");
portName=Console::ReadLine();
//arduino settings
SerialPort^ arduino;
arduino = gcnew SerialPort(portName, baudRate);
//open port
try
{
arduino->Open();
while(1)
{
int k = getch();
key = k.ToString();
Console::WriteLine(key);
arduino->Write(key);
if (k == 32)
return 0;
}
}
catch (IO::IOException^ e )
{
Console::WriteLine(e->GetType()->Name+": Port is not ready");
}
}
This code works fine, and sends commands to the arduino. I might as well ask this as well, but after 35 key strokes it just stops sending key strokes, I am unsure as to why, but that is not an arduino problem (I don't think).
So when the certain value for key gets sent to the arduino, it changes. For example, the values that are assigned to the variable key for pressing the number 1 and 2 are 49 and 50, respectively. However, when they get sent to the arduino, the values are different some how. 1 is now 57, and 2 is now 48. I am unsure as to why this is happening. I tried 4 and 5 and they both have their values shift down 2 like the key 2. This is the code I have on the arduino:
int ledPin = 13;
int key=0;
int c;
void setup()
{
pinMode(ledPin, OUTPUT); // pin will be used to for output
Serial.begin(9600); // same as in your c++ script
}
void loop()
{
if (Serial.available() > 0)
{
key = Serial.read(); // used to read incoming data
if (key == 57)
{
digitalWrite(ledPin, HIGH);
}
else if (key == 48)
{
digitalWrite(ledPin, LOW);
}
}
c = key;
Serial.println(c);
}
As of right now it is just to switch a light on and off. I am hoping to involve many more keys and having the values be consistent would be very convenient. Anyways, if anyone could help me with why the values are different that would be awesome. I am not completely new to programming but I am certainly no expert and have not gotten too far into advanced stuff.
Thank you for any help or advice.
This has to do with what you are sending through visual studio. You are converting a keypress to its ASCII value, then converting that ASCII value to string, then sending that string through serial. The arduino is expecting a number, not a string.
For example, if you press the 1 key, your visual studio code converts that to an ASCII number 49, which is then converted to string "49", which the Arduino receives - but since you are sending "49", which is a "4" and an "9", the Arduino is reading 9 which corresponds to 57, as you have seen.
Similarly, pressing 2 converts it to "50", and the Arduino reads "0" which corresponds to the value 48 which you were getting.
To fix this, send the number directly, don't convert it into a string.