severo
Joined: 01 Feb 2013
Posts: 3
|
| PIC One-wire problem |
 Posted: Wed May 22, 2013 3:40 pm |
 |
|
Hello everyone
I'm pretty sure my problem is basic OW stuff. All I am trying to do is read the ROM number of an EEPROM.
I have an EEPROM (DS2431) that I am interfacing with a Single-Channel 1-Wire Master (DS2482-100) and a PIC18F47J11.
I am trying to read the ROM of the EEPROM with the following code:
| Code: |
void main()
{
setup_timer_4(T4_DISABLED,0,1);
setup_comparator(NC_NC_NC_NC);// This device COMP currently not supported by the PICWizard
int i=0;
BYTE rom_and_crc[8]={0,0,0,0,0,0,0,0};
DS2482_write_config(CONFIG_APU); // Configures the active pullup MOSFET mode.
if(DS2482_detect(DS2482_I2CAddr))
{
printf("\rDS2842: detected\n\r");
if(OWReset())
{
OWWriteByte(0x33); //READ ROM COMMAND
for(i=0; i<8; i++) rom_and_crc=[i]=OWReadByte();
}
while(1);
}
}
|
But all I get back is 00 18 18 18 18 18 18 18.
The OWWriteByte and OWReadByte functions are as follows:
| Code: |
BYTE OWReadByte(void)
{
BYTE data, status;
int poll_count = 0;
// 1-Wire Read Bytes (Case C)
// S AD,0 [A] 1WRB [A] Sr AD,1 [A] [Status] A [Status] A\
// \--------/
// Repeat until 1WB bit has changed to 0
// Sr AD,0 [A] SRP [A] E1 [A] Sr AD,1 [A] DD A\ P
//
// [] indicates from slave
// DD data read
I2C_start();
I2C_write(I2C_address | I2C_WRITE_FLAG);
I2C_write(CMD_1WRB);
I2C_start();
I2C_write(I2C_address | I2C_READ_FLAG);
// loop checking 1WB bit for completion of 1-Wire operation
// abort if poll limit reached
status = I2C_read(ACK);
do
{
status = I2C_read(status & STATUS_1WB);
}
while ((status & STATUS_1WB) && (poll_count++ < POLL_LIMIT));
// check for failure due to poll limit reached
if (poll_count >= POLL_LIMIT)
{
// handle error
// ...
DS2482_reset();
return 0;
}
I2C_start();
I2C_write(I2C_address | I2C_WRITE_FLAG);
I2C_write(CMD_SRP);
I2C_write(0xE1);
I2C_start();
I2C_write(I2C_address | I2C_READ_FLAG);
data = I2C_read(NACK);
I2C_stop();
return data;
}
BYTE OWWriteByte(BYTE sendbyte)
{
// set strong pull-up enable
c1WS = 0;
cSPU = CONFIG_SPU;
cPPM = 0;
cAPU = 0;
// write the new config
DS2482_write_config(c1WS | cSPU | cPPM | cAPU);
// perform write byte
BYTE status;
int poll_count = 0;
// 1-Wire Write Byte (Case B)
// S AD,0 [A] 1WWB [A] DD [A] Sr AD,1 [A] [Status] A [Status] A\ P
// \--------/
// Repeat until 1WB bit has changed to 0
// [] indicates from slave
// DD data to write
I2C_start();
I2C_write(I2C_address | I2C_WRITE_FLAG);
I2C_write(CMD_1WWB);
I2C_write(sendbyte);
I2C_start();
I2C_write(I2C_address | I2C_READ_FLAG);
// loop checking 1WB bit for completion of 1-Wire operation
// abort if poll limit reached
status = I2C_read(ACK);
do
{
status = I2C_read(status & STATUS_1WB);
}
while ((status & STATUS_1WB) && (poll_count++ < POLL_LIMIT));
I2C_stop();
// check for failure due to poll limit reached
if (poll_count >= POLL_LIMIT)
{
// handle error
// ...
DS2482_reset();
return FALSE;
}
else return TRUE;
}
|
Did anyone encounter a similar problem? Or maybe I'm just doing everything wrong. If so, does anyone have an example on how to read the ROM number?
Thanks  |
|
FAQ 
Search
Register
Profile 
Log in to check your private messages 
Log in
