@PaulS. Again, Thank you for your time.
I plan to attach here my code - uno as master and mega as slave. The mega's initial configuration is with the offending (???) code, the following three lines, commented out:
// This seems to force a local event call this routine again ( see setup )
// forcing an event handler loop ( I2C from Master - onRequest ) until
// the stack overflows. It seems that I need to better differentiate the
// Wire.requestFrom( ... ) and the sensors.requestTemperatures( ) interrupts
/* --- Uncomment this section to realize the problem looping. ---
Serial.println( "Request Handler Looping..." );
sensors.requestTemperatures( ); // This causes looping, or so I think.
temp0 = sensors.getTempFByIndex( 0 ) * 10; // Only one sensor attached.
*/
Serial debug for two cases is also included - I2C only with just random data returned from the sensors module showing both the Master and Slave outputs. Then one sample with the slave enabling the one-wire temperature sensor polling and reading. This is where the troubled "event handler" looping plays in.
So here goes. UnoMaster I2C sketch - simply loops polling the MegaSlave for data - random samples or temperature readings, printing them as a formatted debug string to the Serial Monitor.
#define NAME "sensors_unoMaster"
#include <Wire.h>
#define LEDpin 13
#define loopDelay 2000
#define setupPause 1000
#define MASTER 11 // device ID #11
#define SLAVE 10 // device ID #10
void setup( ) {
pinMode( LEDpin, OUTPUT );
Wire.begin( );
Serial.begin( 9600 );
delay( setupPause ); // Pause for a second...
Serial.print( NAME );
Serial.print( " set up complete. Master polling mode.\n" );
return;
}
void loop( ) {
digitalWrite( LEDpin, ( digitalRead( LEDpin ) != HIGH ? HIGH : LOW ) );
// Request from MegaSlave 4 temperature sensor readings @ 2 bytes ints each.
int count = Wire.requestFrom( SLAVE, 8, true );
while ( 8 < Wire.available( ) ) { } // Wait until all 8 bytes are available.
if ( count >= 8 ) {
float temp0 = ( Wire.read( ) << 8 | Wire.read( ) ) / 10.0;
float temp1 = ( Wire.read( ) << 8 | Wire.read( ) ) / 10.0;
float temp2 = ( Wire.read( ) << 8 | Wire.read( ) ) / 10.0;
float temp3 = ( Wire.read( ) << 8 | Wire.read( ) ) / 10.0;
// Build and print a serial debug output string of the data.
String print_string = "Temperature data: "
+ String( temp0 ) + ", "
+ String( temp1 ) + ", "
+ String( temp2 ) + ", "
+ String( temp3 );
Serial.println( print_string );
} else {
Serial.print( "Bad sensor data. count = " );
Serial.println( count );
}
delay( loopDelay );
return;
}
...and the MegaSlave sketch is set into a waiting mode, awaiting a request from the Master for new data, at which time it will respond with: 1) randomly generated sample data to example the I2C, or 2) real sensor probe readings (only one for the post) with three random samples to fill out the Master's request for 8-bytes. (Ultimately, there will be six temperature probes attached.)
#define NAME "sensors_megaSlave"
#define NAME "sensors_megaSlave"
#include <Wire.h>
#include <OneWire.h>
#include <DallasTemperature.h>
#define ONE_WIRE_BUS 12 // DS18B20 1-wire temperature data pin [digital]
#define LEDpin 13
#define loopDelay 2000
#define idleDelay 100
#define setupPause 1000
#define MASTER 11 // device ID #11
#define SLAVE 10 // device ID #10
// Setup oneWire instance to communicate with Temperature sensor
OneWire oneWire( ONE_WIRE_BUS );
// Initialize Dallas Temperature setup with the oneWire reference
DallasTemperature sensors( &oneWire );
void setup( ) {
pinMode( LEDpin, OUTPUT );
randomSeed( analogRead( 0 ) );
Serial.begin( 9600 );
Wire.begin( SLAVE );
Wire.onRequest( requestEvent ); // register I2C request event handler
sensors.begin( );
discoverOneWireDevices( ); // Optional
delay( setupPause ); // ...pause a sec
Serial.print( NAME ); // Serial debug commenting.
Serial.print( " set up complete. Slave wait mode.\n" );
return;
}
void loop( ) {
delay( idleDelay );
return;
}
void requestEvent( ) {
digitalWrite( LEDpin, ( digitalRead( LEDpin ) != HIGH ? HIGH : LOW ) );
unsigned int temp0, temp1, temp2, temp3; // Typed for I2C as 2-bytes each.
// No sensors when testing the I2C bus only.
temp0 = random( 1000 ); // round( sensors.getTempFByIndex( 0 )*10 );
temp1 = random( 1000 ); // round( sensors.getTempFByIndex( 1 )*10 );
temp2 = random( 1000 ); // round( sensors.getTempFByIndex( 2 )*10 );
temp3 = random( 1000 ); // round( sensors.getTempFByIndex( 3 )*10 );
// This seems to force a local event call this routine again ( see setup )
// forcing an event handler loop ( I2C from Master - onRequest ) until
// the stack overflows. It seems that I need to better differentiate the
// Wire.requestFrom( ... ) and the sensors.requestTemperatures( ) interrupts
/* --- Uncomment this section to realize the problem looping. ---
Serial.println( "Request Handler Looping..." );
sensors.requestTemperatures( ); // This causes looping, or so I think.
temp0 = sensors.getTempFByIndex( 0 ) * 10; // Only one sensor attached.
*/
// Build a serial degug output string and print it.
String print_string = "Temperature sensors: "
+ String( temp0 / 10.0 ) + ", "
+ String( temp1 / 10.0 ) + ", "
+ String( temp2 / 10.0 ) + ", "
+ String( temp3 / 10.0 );
Serial.println( print_string );
// I2C data setup and transmission
while ( Wire.available( ) ) { }
uint8_t tempData[8] = {
uint8_t( ( temp0 >> 8 ) ), uint8_t( ( temp0 << 8 ) >> 8 ),
uint8_t( ( temp1 >> 8 ) ), uint8_t( ( temp1 << 8 ) >> 8 ),
uint8_t( ( temp2 >> 8 ) ), uint8_t( ( temp2 << 8 ) >> 8 ),
uint8_t( ( temp3 >> 8 ) ), uint8_t( ( temp3 << 8 ) >> 8 ) };
Wire.write( tempData, 8 );
return;
}
void discoverOneWireDevices( void ) {
byte i;
byte present = 0;
byte data[12];
byte addr[8];
delay( 500 );
Serial.println( "\nLooking for 1-Wire devices..." );
while( oneWire.search( addr ) ) {
Serial.print( "Found \'1-Wire\' device with address: " );
for( i = 0; i < 8; i++ ) {
Serial.print( "0x" );
if ( addr[i] < 16 ) {
Serial.print( '0' );
}
Serial.print( addr[i], HEX );
if ( i < 7 ) {
Serial.print( ", " );
}
}
Serial.println( );
if ( OneWire::crc8( addr, 7 ) != addr[7] ) {
Serial.println( "*** CRC is not valid! ***\n" );
return;
}
}
Serial.println( );
oneWire.reset_search( );
return;
}
This is the sample obtained from the serial monitor for the base test case:
sensors_unoMaster set up complete. Master polling mode.
Temperature data: 53.60, 95.70, 40.50, 64.00
Temperature data: 17.20, 17.30, 46.90, 98.90
Temperature data: 38.20, 3.10, 86.40, 50.60
Temperature data: 65.20, 28.10, 76.50, 89.80
Temperature data: 78.10, 30.50, 24.20, 44.60
...
*** And the slave: ***
Looking for 1-Wire devices...
Found '1-Wire' device with address: 0x28, 0xEE, 0xDE, 0xEE, 0x12, 0x16, 0x01, 0x99
sensors_megaSlave set up complete. Slave wait mode.
Temperature sensors: 39.60, 34.00, 26.30, 81.20
Temperature sensors: 52.40, 24.50, 89.20, 15.40
Temperature sensors: 41.40, 65.20, 21.20, 98.60
Temperature sensors: 89.10, 91.80, 20.20, 6.20
Temperature sensors: 26.70, 7.10, 41.20, 82.00
...
Do not worry about the absolute numbers.
Finally, a serial monitor sample of the Mega slave module trying to poll and read the 1-wire temperature probe sensors.
Looking for 1-Wire devices...
Found '1-Wire' device with address: 0x28, 0xEE, 0xDE, 0xEE, 0x12, 0x16, 0x01, 0x99
Request Handler Looping...
Request Handler Looping...
Request Handler Looping...
Request Handler Looping...
Request Handler Looping...
...
Only thing that I have left is an image of the wiring - I am not good at the schematics yet, no drawing tools. But stuff to learn I guess.
The right side of the mini bread board is the I2C connections using two 1K pull-ups to 5V - hard to see. It includes a Vin to Vin (Mega to Uno) parasitic power for the uno for I have but one power cord and one usb connector. So, parasitic power it is for now.
The left side is the 1-wire temperature setup w/ a 4.7K pull-up and bus connection to digital pin #12.
Well at this point, I do not know what else to supply. If more is needed, please let me know.
Thank you,
Greg