what is role of SSPADD in i2c

[hirataqdees]

hey
can any one tell me what is the role of sspadd reg in i2c.
i want to connct a tmp snsor wid pic18f452.. and my crystal is of 12mhz.what shouil be the vaue of sspadd.its very urgent
regards

 

[shreyas_patel21]

given in datasheet.

When the SSP is configured in Master mode, the lower seven bits of SSPADD act as the baud rate generator reload value.

use below settings:
SSPM3:SSPM0 bits = 1000 = I2C Master mode, clock = FOSC / (4 * (SSPADD+1))

now for 12 Mhz if you want to use 100khz for I2C clock
then SSPADD should be 0x1e i.e. 30decimal

 

[gopinatarajan]

What shall i put if my PIC is a slave?

Can i assign my SSPADD as 0b0111000 which as a slave address?

 

[shreyas_patel21]

Hi,

SSPCON:
SSPM3:SSPM0: Synchronous Serial Port Mode Select bits
1111 = I2C Slave mode, 10-bit address with START and STOP bit interrupts enabled
1110 = I2C Slave mode, 7-bit address with START and STOP bit interrupts enabled
1011 = I2C Firmware Controlled Master mode (Slave IDLE)
1000 = I2C Master mode, clock = FOSC / (4 * (SSPADD+1))
0111 = I2C Slave mode, 10-bit address
0110 = I2C Slave mode, 7-bit address

Once the MSSP module has been enabled, it waits for a START condition to occur. Following the START condition, the 8-bits are shifted into the SSPSR register. All incoming bits are sampled with the rising edge of the clock (SCL) line. The value of register SSPSR<7:1> is compared to the value of the SSPADD register.

so you can assign SSPADD as 0b0111000 and your master should send this sequence.