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////////////////////////////////////////////////////////////////////////////////////
// I2C test program for Digital Photoreactor Controller using TinyWireS library //
// Run this slave program on the AtTiny85. //
////////////////////////////////////////////////////////////////////////////////////
// This test program is adapted from the TinyWireS stress test program //
// developed by Scott Hartog: https://github.com/rambo/TinyWire //
// //
// The slave program receives via I2C N bytes of random data in a single //
// receiveEvent() callback and stores that data in a global buffer. //
// It then responds the first requestEvent() callback with the same data. //
// The requestEvent() callback overwrites the data buffer with zeros after //
// responding so it will only respond correctly to the first requestEvent() //
// callback after each receiveEvent() callback. Subsequent requestEvent() //
// will respond with 0xff for all data bytes. //
// //
// //
// SETUP: //
// AtTiny85 Pin 2 = PB3 = Blink LED //
// Attiny85 Pin 3 (PB4) = LED PWM //
// AtTiny85 Pin 5 (PB0/SDA) = I2C SDA //
// connect to SDA on master with external pull-up (~4.7K) //
// AtTinyPin 6 (PB1) = Fan PWM //
// AtTiny Pin 7 (PB0/SCL) = I2C SCL //
// connect to SCL on master with external pull-up (~4.7K) //
// AtTiny Pin 1 (PB5/!RST) //
// connect to reset on master (or just pull-up) //
// //
////////////////////////////////////////////////////////////////////////////////////
#include "TinyWireS.h" // wrapper class for I2C slave routines
#define I2C_SLAVE_ADDR 0x26 // I2C slave address (38, 0x26),
uint8_t master_data[16]; // global buffer to store data sent from the master.
uint8_t master_bytes; // global variable to number of bytes sent from the master.
const int LEDPin = 4; //Arduino pin 4, pin 3 on AtTiny85 pinout
const int FanPin = 1; //Arduino pin 1, pin 6 on AtTiny85 pinout
const int BlinkPin = 3; //Arduino pin 3, pin 2 on AtTiny85 pinout
// Gets called when the ATtiny85 receives an I2C write slave request
void receiveEvent(uint8_t num_bytes)
{
uint8_t i;
// save the number of bytes sent from the master
master_bytes = num_bytes;
// store the data from the master into the data buffer
for (i = 0; i < master_bytes; i++)
master_data[i] = TinyWireS.receive();
// set LED and Fan PWM duty to random byte values recieved from the master
analogWrite(FanPin, master_data[0]);
analogWrite(LEDPin, master_data[1]);
// blink LED whenever data is successfuly recieved
digitalWrite(BlinkPin, HIGH);
delay(10);
digitalWrite(BlinkPin, LOW);
delay(10);
}
// Gets called when the ATtiny receives an i2c read slave request
void requestEvent()
{
uint8_t i;
// send the data buffer back to the master
for (i = 0; i < master_bytes; i++)
TinyWireS.send(master_data[i]);
// corrupt the byte values in the data buffer
// so that subsequent call won't match
for (i = 0; i < master_bytes; i++)
master_data[i] += 0x5a;
// corrupt length of the request, but dont' make it zero
// if the usiTwiSlave.c is working fine, then this number is completely irrelevant
// because the requestEvent() callback will not be called again until
// after the next receiveEvent() callback, so the master_data and
// master_bytes variables will be set by that call.
// If the usiTwiSlave.c has the issue of calling the requestFrom() callback
// for each byte sent, the buffer will accumulate by this amount *for each byte
// in the original request*.
//
// Making it zero will obscure the 1-byte send issue in the usiTwiSlave.c
// that is being tested.
// Making it small will allow a few requests to succeed before the tx buffer
// overflows and the usiTwiSlave.c hangs on the "while ( tmphead == txTail );"
// line
master_bytes = 2;
}
void setup()
{
// initialize the TinyWireS and usiTwiSlave libraries
TinyWireS.begin(I2C_SLAVE_ADDR); // init I2C Slave mode
// register the onReceive() callback function
TinyWireS.onReceive(receiveEvent);
// register the onRequest() callback function
TinyWireS.onRequest(requestEvent);
pinMode(LEDPin, OUTPUT); // set pin for LED PWM
pinMode(FanPin, OUTPUT); // set pin for Fan PWM
pinMode(BlinkPin, OUTPUT); // set pin to blink LED
TCCR0B = TCCR0B & 0b11111000 | 0b001; // sets internal timer of AtTiny85 to 31250 Hz for fast PWM for controlling fan speed
}
void loop()
{
// this needs to be here
/////////////Does this really need to be here?????
//TinyWireS_stop_check();
// otherwise empty loop
}
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