Hey Michael, 

really nice project! I would like to give it a try but I don't get what you mean with the adjustment of the i2c clock. I read in the user guide something about clock stretching but I don't know how to implement that in the source code. What do I have to change in the source code so that it´s working? 


Greetings from a not-programmer ;)

Hey Eric, what micro controller are you using? Sorry for the late reply :)

By the way, the entire project is on halt as I have moved and there is only a single tomato plant left. But there is hopefully some useful stuff here.

Hi Micheal,

Many thanks for your response.

The pullup resisters have been implemented. The strange thing here is we can read the temperature ( build on this probe ) smoothly but the huminity value seems not stable. These days we always received value over 900 (raw value). 

I also change the sensor to Arduino again but its still not return exact  value as it used to be.

The unsatability is what I encounter, so of you have any experience on this, please advise.

Thank you and have a nice weekend.

Hello Michael,

Really interesting for your share.

I am now in the same situation to make Chirp wirk with my MPS430F5310.

I have work with these sensor for my Arduino and Panstamp (also AVR), everything is fine. But when switch to MSP430, there are some problems happened:

- Sometime it make the MCU halt and when reset, I can not connect to this sensor again.

- Sometime they return with raw value over 930 continuously (although with the soil-moisture of 100%, I usually get maximum of 534 raw value)

- With the same code, some of my node run well but not the same with the others.

I share my code here:

void Chirp_Init(unsigned char addr) // Init Chirp
{
UCB0CTL1 |= UCSWRST;
UCB0I2CSA = addr; // Send address
UCB0CTL1 &= ~UCSWRST;                           
while (UCB0STAT & UCBUSY);               
UCB0CTL1 |= UCTR;                         
UCB0CTL1 |= UCTXSTT;                     
UCB0TXBUF=6; // Send 6 for reset
timeout=0;
while(!(UCB0IFG & UCTXIFG))
UCB0CTL1 |= UCTXSTP;  
delayms(50);
}

unsigned int Chirp_read(unsigned char addr, unsigned char reg)
{ unsigned char i=0;
char data[2];
unsigned long Doamdat;

UCB0CTL1 |= UCSWRST;
  UCB0I2CSA = addr;   //Send address
  UCB0CTL1 &= ~UCSWRST;                      
  while (UCB0STAT & UCBUSY);                
  UCB0CTL1 |= UCTR;               // Send bit for write          
  UCB0CTL1 |= UCTXSTT;            //Send bit Start          
  UCB0TXBUF=reg; //Send register for read
  while(!(UCB0IFG & UCTXIFG));
  UCB0CTL1 |= UCTXSTP; //Send bit Stop
  while(UCB0CTL1 & UCTXSTP);
  delayms(80); // Delay for chirp ready
  UCB0CTL1 &= ~UCTR;              //Send bit for read
  UCB0CTL1 |= UCTXSTT;            //Send bit start

  while(UCB0CTL1 & UCTXSTT);                
  while(!(UCB0IFG & UCRXIFG));  
  data[i++] = UCB0RXBUF; // Read MSB
  while(!(UCB0IFG & UCRXIFG));              
  data[i++] = UCB0RXBUF; //Read LSB
  UCB0CTL1 |= UCTXSTP;            //Send bit Stop
  while(UCB0CTL1 & UCTXSTP);
  //P5OUT &= ~BIT2;
  Doamdat=((data[0])<<8)|(data[1]); //Value = MSB<<8 + LSB

return Doamdat; //return value
}

Any of your advice is highly appreciate.

Thank you.

Tri.

Hey Tri,

thanks for your comment!

I'm afraid I am not using the raw C libraries for the MSP430. I use Energia, an Arduino port. Perhaps your problems come from a wiring problem: are all calbes connected properly? Do you have the proper pull-up resistors in place?