SNOSD82C June 2018 – April 2021 TMP117
The user can write a register address to the pointer register to access a particular register on the TMP117. The value for the pointer register is the first byte transferred after the slave address byte with the R/ W bit low. Every write operation to the TMP117 requires a value for the pointer register.
When reading from the TMP117, the last value stored in the pointer register by a write operation is used to determine which register is read during a read operation. To change the register pointer for a read operation, a new value must be written to the pointer register. The user can issue an address byte with the R/ W bit low, followed by the pointer register byte to write a new value for the pointer register. No additional data is required. The master can then generate a START condition and send the slave address byte with the R/ W bit high to initiate the read command. See Figure 7-10 for details of this sequence. If repeated reads from the same register are desired, it is not necessary to send the pointer register bytes continuously because the TMP117 retains the pointer register value until the value is changed by the next write operation.
Register bytes are sent with the most significant byte first, followed by the least significant byte.