SNIS207 December 2018 LM95071-Q1
The LM95071-Q1 operates as a slave and is compatible with SPI or MICROWIRE bus specifications. Data is clocked out on the falling edge of the serial clock (SC), while data is clocked in on the rising edge of SC. A complete communication is framed by falling and rising chip select (CS) signal. The CS signal should be held high for at least one clock cycle (160 ns minimum) between communications. The transmit-only communication (register read) consists of 16 clock cycles. A complete transmit/receive communication will consist of 32 serial clocks (see Serial Bus Timing Diagrams). The first 16 clocks comprise the transmit phase of communication, while the second 16 clocks are the receive phase.
When CS is high SI/O will be in TRI-STATE. Communication should be initiated by taking chip select (CS) low. This should not be done when SC is changing from a low to high state. Once CS is low the serial I/O pin (SI/O) will transmit the first bit of data. The master can then read this bit with the rising edge of SC. The remainder of the data will be clocked out by the falling edge of SC. CS can be taken high at any time during the transmit phase. If CS is brought low in the middle of a conversion the LM95071-Q1 will complete the conversion and the output shift register will be updated after CS is brought back high.
The receive phase of a communication starts after 16 SC periods. CS can remain low for 32 SC cycles. The LM95071/LM95071-Q1 will read the data available on the SI/O line on the rising edge of the serial clock. Input data is to an 8-bit shift register. The part will detect the last eight bits shifted into the register. The receive phase can last up to 16 SC periods. All ones must be shifted in order to place the part into shutdown. All zeros must be shifted in order to place the LM95071-Q1 into continuous conversion mode. Only the following codes should be transmitted to the LM95071-Q1:
Another code may place the part into a test mode. Test modes are used by Texas Instruments to thoroughly test the function of the LM95071-Q1 during production testing. Only eight bits have been defined above since only the last eight transmitted are detected by the LM95071-Q1, before CS is taken HIGH.
The following communication can be used to determine the Manufacturer's/Device ID and then immediately place the part into continuous conversion mode. With CS continuously low:
Note that 228 ms (max) will have to pass for a conversion to complete before the LM95071-Q1 actually transmits temperature data.