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Save gileri/5a9285d6a1cfde142260 to your computer and use it in GitHub Desktop.
http://bradsrpi.blogspot.fr/2013/03/sending-data-from-arduino-to-raspberry.html |
#include <Wire.h> | |
#define SLAVE_ADDRESS 0x04 | |
#define FLOATS_SENT 2 | |
float temperature = 10.5; | |
float luminosity = 5.2; | |
float data[FLOATS_SENT]; | |
void setup() { | |
pinMode(13, OUTPUT); | |
Serial.begin(9600); | |
data[0] = temperature; | |
data[1] = luminosity; | |
// initialize i2c as slave | |
Wire.begin(SLAVE_ADDRESS); | |
// define callbacks for i2c communication | |
Wire.onRequest(sendData); | |
} | |
void loop() { | |
delay(100); | |
} | |
void sendData(){ | |
Wire.write((byte*) &temperature, FLOATS_SENT*sizeof(float)); | |
} |
import time | |
import struct | |
import smbus | |
# 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 get_data(): | |
return bus.read_i2c_block_data(address, 0, 8) | |
def get_float(data, index): | |
bytes = data[4*index:(index+1)*4] | |
return struct.unpack('f', "".join(map(chr, bytes)))[0] | |
while True: | |
try: | |
data = get_data() | |
print(get_float(data, 0)) | |
print(get_float(data, 1)) | |
except Exception as e: | |
print(e) | |
continue | |
finally: | |
time.sleep(1) |
I'm a bit late to the party, I'm sure you guys have figured it out by now. I've only done 1 unit in JAVA data structures so this it might not be the best way but its what worked for me.
Arduino slave
#include "ph_grav.h" //my headerfile
#include <Wire.h>
#define SLAVE_ADDRESS 0x08 // arduino slave address
volatile float pHreading;
Gravity_pH pH = Gravity_pH(A0);
//int FLOATS_TO_SEND = 4;
void setup() {
Wire.begin(SLAVE_ADDRESS);
Wire.onReceive(receiveData);
Wire.onRequest(sendData); //send data when raspberry askes for it
}
void loop() {
noInterrupts(); // inssure the reading and data sending not a the same time
pHreading = (pH.read_ph()); // my sensor function, use what ever float you want
interrupts();
delay(1000);
}
void sendData()
{
Wire.write((uint8_t*) &pHreading, sizeof(float)); // writes the float to wire (4 bytes)
}
//just make a for loop to send an array of floats e.g
//for ( int i = 0; i < FLOATS_TO_SEND; i++){
//Wire.write((uint8_t*) &pHreading[i], sizeof(float));}
//and the same on the raspberry pi side
void receiveData(int bytecount)
{
//if you want to do something when the rasberry sends data
}
Raspberry master
import struct
import smbus
import time
bus = smbus.SMBus(1) # raspberry pi address this might be (0) if on older raspberry pi's
address = 0x08 #address of arduino
def get_data():
temp = bytearray(bus.read_i2c_block_data(address, 1, 1)) # through away the first byte as this is the ack byte
return bytearray(bus.read_i2c_block_data(address, 1, 4));# return 4 bytes in a array ( bytes sent from arduino)
while True:
time.sleep(1);
data = get_data()
data2 = struct.unpack('f', data) # convert the array of bytes to floats
print(data2); #check the it worked
I am also late to the party ;-) hopefully there is still somebody around.
Basically, it does exactly what I want. The modification
read_i2c_block_data(address, 0, 8);
is essential (and python would not complain about the semicolon???).
Otherwise, without the third parameter, the Arduino runs wild and keeps sending 255 and would not stop.
But I have a problem:
The parameter "cmd", which is 0 in this case, is not understood by the Arduino.
When reading from the raspi, the Arduino confuses this 0 with other incoming data.
So this solution works one-way only.
I found another solution here:
https://stackoverflow.com/questions/14420372/how-to-read-data-from-arduino-with-raspberry-pi-with-i2c?rq=2
i2c_msg can be used to request the amount of data needed.
Wow, thanks for the interest in the script !
I cleaned up the script and implemented the read size based on @wicusverhoef's suggestion. However I can't test it right now, I count on you lads :)
This is the program we setup in the Rpi
import smbus
import time
import struct
bus = smbus.SMBus(1)
address = 0x04
def get_data():
return bus.read_i2c_block_data(address, 0);
def get_float(data_bytes,index):
bytes = data_bytes[4index:4index+4]
aux = bytearray(bytes)
data_float=struct.unpack('<f',aux)[0]
return data_float
while True:
try:
data = get_data()
print(str(get_float(data, 0))+" dB")
print(str(get_float(data, 1))+" index")
print(str(get_float(data, 2))+" ppm")
print(" ")
except:
continue
time.sleep(1);
This is the program we setup in the Arduino Program
#include <Wire.h>
#define SLAVE_ADDRESS 0x04
#define FLOATS_SENT 3
float audio = 10.5;
float uv = 5.2;
float aire = 1500.8;
float data[FLOATS_SENT];
void setup() {
pinMode(13, OUTPUT);
Serial.begin(9600);
}
void loop() {
delay(100);
}
void sendData(){
Wire.write((byte*) &data, FLOATS_SENT*sizeof(float));
}