• State TI Thinks Resolved
  • Locked Locked
  • Replies 1 reply
  • Answers 1 answer
  • Subscribers 46 subscribers
  • Views 212 views
  • Users 0 members are here
Support feedback
Options
Options
Related

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

AFE4490SPO2EVM: Data received from register interpretation

Art Mecina
Genius 16655 points
Part Number: AFE4490SPO2EVM

Hello Guys,

Good day.

Our customer is working on AFE4490SPO2EVM and need help on the interpretation of the data received from the register.  For example, he wants to read the data from register 'LED1VAL' with hex address '2C'. According to Message Communication Protocol, If he send '0x03 0x32 0x43 0x0D' to EVM then it returns '0x03 0x02 0x19 0xFF 0x1F 0x03 0x0D'. The middle 3 bytes are the raw data but how should it be interpreted?

Does it mean the the data would be 0x19 0xFF 0x1F with LSB (Least Significant Bit) first? So it can be converted to binary of "111110001111111110011000". According to data sheet, first two bits are ignored, rest 22 bits is calculated as -1.2v*1638296/2^21=-0.93744v (The first bit is treated as symbol of 'Negative', then 1638296 is converted from rest of 21 binary bits). Is this right?

http://e2e.ti.com/cfs-file.ashx/__key/communityserver-discussions-components-files/30/2072.Message-Communication-Protocol-_2D00_-AFE44x0SPO2EVM.pdf

Thanks!

Art

  • 0
    TI__Mastermind 49906 points

    Hello Art,

    If the data received is 0x19 0xFF 0x1F with LSB (least significant byte) first, then the data would be represented as 0x1FFF19

    0x1FFF19 in ADC codes translates to ~1.2V. This code implies that the data is saturated.

    To bring the signal chain out of saturation, the LED current or TIA gain must be reduced.