2. I2C Interface
The Si7060 complies with “fast” mode I
2
C operation and 7-bit addressing at speeds up to 400 kHz.
The I
2
C address is factory programmed to one of 4 values 0x30, 0x31, 0x32, or 0x33 (0110000b through 0110011b).
At power-up the registers are initialized, as will be described in the register definitions, and then they can be read or written in standard
fashion for I
2
C devices.
The host command for writing an I
2
C register is:
START Address W ACK register ACK data ACK STOP
The host command for reading an I
2
C register is:
START Address W ACK register ACK Sr Address R Data NACK* STOP
*NACK by host
Where:
START is SDA going low with SCL high
Sr is a repeated START
Address is 0x30 up to 0x33.
0 indicates a write and 1 indicates a read.
ACK is SDA low.
Data is the Read or Write data.
NACK is SDA high.
STOP is SDA going high with SCL high.
Writing
or
Reading of sequential registers can be supported by setting the arautoinc bit of register 0xC5 (see register description). In
the case of a read sequence where the arautoinc bit has been set, the data can be ACK’d to allow reading of sequential registers. For
example, a two byte read of the conversion data in registers 0xC1 and 0XC2 would be:
START Address W ACK 0xC1 ACK Sr Address ACK data ACK* data NACK* STOP
*ACK/NACK by host
To wake a part from sleep mode or to interrupt a measurement loop from idle mode, send the sequence:
START Address W ACK STOP
In this
case, if the host continued with a register write, the Si7060 would NACK which would be unexpected. Additionally, the following
sequence can be used to wake the part up or to interrupt a measurement loop:
START Address R ACK data NACK* STOP
*NACK by host
In this case, the Si7060 will produce 0xFF for the data. Allow for 10 μsec between
the ACK of the address and the next START for the
Si7060 to wake from sleep. In most cases, this will happen automatically, due to the 400 KHz maximum speed of the I
2
C bus. The
sequence will put the part in idle mode with the stop bit set.
To make a single conversion, having woken the part, set the oneburst bit of register 0xC4 to 1 and the stop bit to 0. The stop bit
resets to 1 by the time the measurement is complete.
To put the part back to sleep after reading the data, set the stop bit to 0.
Putting the part to sleep with the sleep bit = 0 will result in the mode of operation where the temperature is sampled every 200 msec,
and the output pin will toggle at the temperature threshold points as defined by registers 0xC6 and 0xC7 (assuming the usestore bit is
also set)—that is, write 0x08 to 0xC4.
If ultra-low power sleep with no sampling is desired, set the stop bit to 0 and the sleep bit to 1—that is, write 0x00 or 0x09 (to retain the
settings of 0xC6 and 0xC7) to 0xC4.
Si7060 Data Sheet
I2C Interface
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