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ADS1018EVM: ADS1018EVM

Wencang Xu
Prodigy 20 points
Part Number: ADS1018EVM
Other Parts Discussed in Thread: ADS1118

We bought your ADS1018EVM to test the temperature for K-Type Thermocouple, but the error is very big, we don't know why?

For this testing, we connect the K-Type Thermocouple to AIN0 (AINP) and AIN1 (AINN), set the FSR as ±0.256 V. The testing steps are:

1) set TS_MODE=1, read the code (code_CJ), then T_CJ=0.125*code_CJ (C), and convert to V_CJ (mV) using K-type thermocouple lookup table

2) set TS_MODE=0, read the code (code_TC), then the voltage V_TC=code_TC*0.256*1000/2048 (mV)

3) Then the actual voltage V_actual=V_CJ + V_TC (mV), convert to temperature (T_actual) using K-type thermocouple lookup table

Do you think if our testing steps are correct? If correct, why the error is so big?

  • 0
    TI__Mastermind 18900 points

    Hello Wencang,

    In general your flow is good. There's some more details in this reference design Simple Thermocouple Measurement Solution Reference Design, <1°C Accurate, which is for the ADS1118. Its not the same device but its the same family so the information in their is very applicable: https://www.ti.com/lit/pdf/slau509

    Anyways, these types of questions of "getting error or an unexpected value" is almost always the result of using continuous conversion instead of single shot (which can be found in the MODE bit field). Can you confirm you were using single shot instead of continuous mode? If not, can you repeat the steps using single shot instead of continuous mode?

    Best,

    -Cole

  • 0
    Prodigy 20 points

    Hi Cole,

    How to configure single shot mode? This bit is locked

  • 0 in reply to Wencang Xu
    TI__Mastermind 18900 points

    Hello Wencang,

    Apologizes, I forgot you're using the GUI and the EVM.

    I believe you can set that bit in the register map and click the collect button on the other page. Let me know if clicking the collect button switches the device back to continuous and I'll find a better solution for you.

    Best,

    -Cole