I have an interesting issue that could or could not be true for the Due only. I do not have the resources to test I2C on 2 Arduino ATMegas. Here is the issue:
I have two Due's: The master has an Ethernet shield that will be used later; is used now for easily differentiate between master and slave. I2C is working, however the setup is: 1 12V battery connected to the Due's DC "round" input connected to the master: 3.3V and GND are tied together between the two boards: 1 USB cable for uploading sketches.
When I unplug the USB from the master to upload a sketch on the slave, both boards remain on during the USB unplugged phase -- due to the 12 DC.
The sketch is uploaded and the USB stay on the slave side for serial monitoring.
THE ISSUE: When the 12V battery is not corrected to the master; during the USB unplugged phase, both boards are off. Upon uploading the same sketch to the slave, the serial monitor shows that no information is received by the slave.
I assume that I2C setup and uploading a sketch are conflicting. How can I resolve this issue, so I don't need power to the Dues all the time. Here is the code that is working with the 12V battery supply.
/**************************************************************************************************
MASTER
****************************************************************************************************/
#include <Wire.h>
byte ISend[4];
void setup()
{
Wire1.begin(); // join i2c bus (address optional for master)
intToByteA((unsigned long)72992);
}
void loop()
{
Wire1.beginTransmission(4); // transmit to device #4
for(int i = 0; i < 4; i++)
{
Wire1.write(ISend[i]);
}
Wire1.endTransmission();
delay(500);
}
void intToByteA(unsigned long num)
{
for (int i = 0; i < 4; i++)
{
ISend[i] = (byte)((num >> (8 * i)) & 0xFF);
}
}
/*********************************************************************************************/
/************************************************************************************************
SLAVE
*************************************************************************************************/
#include <Wire.h>
byte IReceive[4];
void setup()
{
Wire1.begin(4); // join i2c bus with address #4
Wire1.onReceive(receiveEvent); // register event
Serial.begin(9600); // start serial for output
}
void loop()
{
delay(223);
}
// function that executes whenever data is received from master
// this function is registered as an event, see setup()
void receiveEvent(int howMany)
{
unsigned long test = 11;
for(int i = 0; i < 4; i++)
{
IReceive[i] = Wire1.read();
}
test = byteAToInt();
Serial.println(test);
}
unsigned long byteAToInt()
{
unsigned long temp = 0;
for (int i = 0; i < 4; i++)
{
temp += (((unsigned long)IReceive[i]) << (8 * i));
}
return temp;
}
