Category: Software
Product Number: DS9092L
Dear AD Team,
In our custom board, we are using the DS9092L+ IButton probe with the DS1990A IButton interfaced with MSP432E4 Microcontroller. However, we are facing difficulties in reading the ROM code of the IButton.
Below are the connections for your reference:
- IButton Probe:
o Green (Data) connected to PORTE- E2 on the microcontroller
o Black (+ve LED) connected to PORTE- E3 on the microcontroller
o White (-ve LED) connected to GND
o Red (Ground) connected to GND
Additionally, we have connected a 4.7kohm resistor for pull-up on the data line.
Problem Facing:
I can able to detect the I Button successfully but could not able to read the 64bit ROM code of the IButton.Reading ROM code i am sending 0x33 command to the I Button.
I Button code:
#ifdef I_BUTTON_INTERFACE
#if 1
int index;
led_init(); // Initialize the LED
I_ButtonInit();
/* Clear the buffer */
memset(&DestBuff[0], 0x00, sizeof(DestBuff));
while(1)
{
onewire_reset();
memset(&DestBuff[0], 0x00, sizeof(DestBuff));
/* Find the One Wire device */
Read_ROMCode(&DestBuff[0]);
UARTprintf("OneWire ROMCode = ");
for (index = 0; index < 8; index++)
{
UARTprintf("0x%x ", DestBuff[index]);
}
UARTprintf("\r\n");
delayms(50);
}
#endif
void led_init() {
UINT8 u8RetVal;
u8RetVal = GPIO_Output_Init(SYSCTL_PERIPH_GPIOK,GPIO_PORTK_BASE,GPIO_PIN_4,GPIO_PIN_4);
ROM_GPIOPinWrite(GPIO_PORTK_BASE, (GPIO_PIN_4), GPIO_PIN_4);
delaySec(1);
ROM_GPIOPinWrite(GPIO_PORTK_BASE, (GPIO_PIN_4), 0);
}
void I_ButtonInit()
{
UINT8 u8RetVal;
u8RetVal = GPIO_Output_Init(SYSCTL_PERIPH_GPION,GPIO_PORTN_BASE,GPIO_PIN_4,GPIO_PIN_4);//PN4 set as output
ROM_GPIOPinWrite(GPIO_PORTN_BASE, (GPIO_PIN_4), GPIO_PIN_4); //making as high
}
unsigned int onewire_reset() {
UINT8 u8RetVal;
u8RetVal = GPIO_Output_Init(SYSCTL_PERIPH_GPION,GPIO_PORTN_BASE,GPIO_PIN_4,GPIO_PIN_4);
ROM_GPIOPinWrite(GPIO_PORTN_BASE, (GPIO_PIN_4), 0);//Making Data line as low
delayus(480);
ROM_GPIOPinWrite(GPIO_PORTN_BASE, (GPIO_PIN_4), GPIO_PIN_4);//Making Data line as high
delayus(70);
u8RetVal = GPIO_Input_Init(SYSCTL_PERIPH_GPION,GPIO_PORTN_BASE,GPION,GPIO_PIN_4,INT_GPION,GPIO_PULLUP_ENABLE,GPIO_FALLING_EDGE,GPIO_INT_DISABLE);//Data line configured as Input
UINT32 presence = ROM_GPIOPinRead(GPIO_PORTN_BASE, GPIO_PIN_4);//Reading the data line status
delayus(410);
UARTprintf("\n");
UARTprintf("Presesnce:%x\n",presence);
if(presence == 0)
{
UARTprintf("I_BUTTON DETECTED\n");
ROM_GPIOPinWrite(GPIO_PORTK_BASE, (GPIO_PIN_4), GPIO_PIN_4);
}
else
{
UARTprintf("I_BUTTON NOT DETECTED\n");
ROM_GPIOPinWrite(GPIO_PORTK_BASE, (GPIO_PIN_4), 0);
}
GPIO_Output_Init(SYSCTL_PERIPH_GPION,GPIO_PORTN_BASE,GPIO_PIN_4,GPIO_PIN_4);//Data line configured as Output
}
void OneWire_WriteByte(char byte)
{
int l;
// Loop to write each bit in the byte, LS bit first
for (l = 0; l < 8; l++)
{
OneWire_WriteBit(byte & 0x01);
byte >>= 1;
}
}
void OneWire_WriteBit(char bit)
{
if (bit)
{
// Write '0' bit for the WriteOne bit
ROM_GPIOPinWrite(GPIO_PORTN_BASE, GPIO_PIN_4, 0);
delayus(6);
ROM_GPIOPinWrite(GPIO_PORTN_BASE, GPIO_PIN_4, GPIO_PIN_4);
delayus(64);
}
else
{
// Write '0' bit for the WriteZero bit
ROM_GPIOPinWrite(GPIO_PORTN_BASE, GPIO_PIN_4, 0);
delayus(70);
ROM_GPIOPinWrite(GPIO_PORTN_BASE, GPIO_PIN_4, GPIO_PIN_4); //if not working change to 0 and check
delayus(10);
}
}
unsigned char OneWire_Readbyte(void)
{
int l;
unsigned char result = 0;
for (l = 0; l < 8; l++)
{
result |= (OneWire_Readbit() << l);
}
return result;
}
unsigned char OneWire_Readbit(void)
{
unsigned char result;
UINT8 u8RetVal;
GPIO_Output_Init(SYSCTL_PERIPH_GPION,GPIO_PORTN_BASE,GPIO_PIN_4,GPIO_PIN_4);//Data line configured as Output
/* Start the Read bit sequence */
ROM_GPIOPinWrite(GPIO_PORTN_BASE, GPIO_PIN_4, 0);
delayus(6);// delayms(6);
ROM_GPIOPinWrite(GPIO_PORTN_BASE, GPIO_PIN_4, GPIO_PIN_4);//if u want to make high uncomment it
delayus(9);
/* Make the pin as Input for reading the data */
u8RetVal = GPIO_Input_Init(SYSCTL_PERIPH_GPION,GPIO_PORTN_BASE,GPION,GPIO_PIN_4,INT_GPION,GPIO_PULLUP_ENABLE,GPIO_FALLING_EDGE,GPIO_INT_DISABLE);//Data line configured as Input
result = ROM_GPIOPinRead(GPIO_PORTN_BASE, GPIO_PIN_4);
delayus(45);
/* Revert back the GPIO state as ouput */
GPIO_Output_Init(SYSCTL_PERIPH_GPION,GPIO_PORTN_BASE,GPIO_PIN_4,GPIO_PIN_4);//Data line configured as Output
return result;
}
void Read_ROMCode(unsigned char *destbuf)
{
int n;
if (NULL == destbuf)
return;
onewire_reset();
OneWire_WriteByte(0x33);
for (n = 0; n < 8; n++)
{
destbuf[n] = OneWire_Readbyte();
}
}
When i keep I button on the probe some random value is coming,if I do not keep printing all 0xFF.
Ibutton Used:DS1990A.
Please let me know what will be the issue in reading ROM code of the I Button.