How to handle ADT7302 from the user space C application? I'm currently developing the SPI application for Linux to read the temp. reading

Question

Currently myself working with ADT7302 SPI sensor for monitoring temperature. 
 
 For that I have connect the sensor to Galileo board or Minnowboard MAX which are running Linux OS. 
 I'm not getting any kind of reading from the MISO line instead I got 0xFF always. 
 
 Now my question is how can I access through standard SPI ioctl syscall and SPI_IOC_MESSAGE macro. 
 Is the ADT7302 is partially read only sensor ? because from the data sheet I don't understand the how the sensor is perform communication to master. there are no any internal register like control register are provided at all. 
 
 I didn't found any kind of documents or code from the Google. So I think you are the only one person to giving me an answer because after all you were develop the driver for the same.

Lluis · Accepted Answer

Hi bhoomil, 
 As per table 2, the maximum clock frequency that can be input to the ADT7302 is 20MHz, what's your serial clock frequency? 
 No, there is no internal registers to be accessed through the SPI actually. Just follow figure 14, and the timing constraints stated, so you will be able to get data from the sensor. A bit of code is also shown in page 13 as a guideline. How often are you pulling the CS low? could you share scope shots of the interface pins (CS, SCLK, DOUT, DIN) so we could have a look at how are you operating the part and advice? 
 Regards, 
 Lluis.)

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How to handle ADT7302 from the user space C application? I'm currently developing the SPI application for Linux to read the temp. reading