hello everyone,
As I am using the NTAG NT3H1101 with MSP430 and trying to interface it with I2C, i am having problem of the behavior of the NTAG. From the datasheet it says that if i send START condition with the Right Slave Address(0x55), i should receive an ACK from the NTAG. but, the NATG is just holding low the 9th clock(there is no 9th clock).
whenever i send a wrong address i see the 9th clock with the whole data sent.
From the side of the MSP430, it says that the START condition clears after receiving a ACK from the NTAG,which never happens and my code stuckes at line where i made a check to makke sure i received the NACK.while (UCB0CTL1 & UCTXSTT);
can you please tell me why the NTAG is not behaving accordingly?
#include /* * main.c */
//***declaration of global variable***************************
unsigned char *ptrRx;
unsigned char RXData[16];
unsigned char RXByte;
int main(void) {
WDTCTL = WDTPW + WDTHOLD;//Stop the WDT to prevent reset
BCSCTL1 = CALBC1_16MHZ; // Set DCO to 16MHz
DCOCTL = CALDCO_16MHZ;
//initialization
// configure P3.1(SDA) an P3.2(SCL) for I2C
P3SEL |=BIT1|BIT2;
P3SEL2 &=~(BIT1|BIT2);
UCB0CTL1 |=UCSWRST; //Ensure that the USCI_B0 is reset before the configuration
UCB0CTL1 &=~UCSLA10; //slve address with 7 bit
UCB0CTL0 |=UCMST|UCMODE_3|UCSYNC; //set the MSP430 to master mode
UCB0CTL1|=UCSSEL_3|UCSWRST; //take USCi clock source from SMCLK //configure the baud rate registers for 100Khz when sourcing from SMCLK,SMCLK=16Mhz UCB0BR0 =64; //lower byte of UCBRx
UCB0BR1 =2;
UCB0CTL1 &=~UCSWRST; // Clear SW reset, take the USCI module out of reset
UCB0I2CSA =0x55; //writing the slave address
IE2 |=UCB0RXIE; // enable Rx interrupt //
__delay_cycles(60000);
while(1){
unsigned char i;//
UCTR =~R/W //slave address of the NTAG NFC //
UCB0TXBUF=0x01;
UCB0CTL1 |=UCTR|UCTXSTT; //transmitter,I2C start condition
while (UCB0CTL1 & UCTXSTT); // Ensure START condition got sent //send memory address
UCB0TXBUF=0x01;
while ((UCB0CTL1 & UCTXSTT) && (!(IFG2 & UCB0TXIFG))); // Ensure START condition got sent and memory address is being read
UCB0CTL1 |=UCTXSTP; //stop condition
UCB0CTL1 &=~UCTR; //receiver mode
UCB0CTL1 |= UCTXSTT; // I2C start condition //receiver mode
__bis_SR_register(LPM0 | GIE); // Enter LPM0 w/ interrupt
for(i=0;i<16;i++){
while(!(IFG2 & UCB0RXIFG)); //wait till we receive the data
*ptrRx=RXByte;
ptrRx++;
if(i==1)
{ UCB0CTL1 |=UCTXSTP; //stop reception
}
}
}
}
#pragma vector = USCIAB0RX_VECTOR
__interrupt void USCIAB0RX_ISR(void) {
//clear interrrupt flag
RXByte = UCB0RXBUF; // Get RX data
__bic_SR_register_on_exit(LPM0); // Exit LPM0
}
