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EVAL-ADICUP3029 & EVAL-AD5941BATZ, AD5940_BATImpedance Problems

Thread Summary

The user encountered incorrect impedance measurement data when using the BATImpedance library with the EVAL-AD5941BATZ kit and IAR. The excitation signal stops after 9 seconds due to the sweep configuration, which limits the measurement to 101 sweep points. The final answer suggests checking the `AppBATCfg.NumOfData` value, which should be set to `-1` for continuous measurements, and adjusting the `PwrMod` setting for frequencies above 80kHz. The user also noted that switching to the AD5940/41ELCZ kit resolved similar issues.
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Category: Software
Product Number: EVAL-ADICUP3029 & EVAL-AD5941BATZ [45891791]

Hi,

After having successfully tested the EVAL-AD5941BATZ kit with the SensorPal software, I wanted to use the BATImpedance library from the GitHub platform to compile with IAR. I manage to compile but when I read the data they are apparently wrong :

The data :

Freq: 1.000000 (real, image) = ,37.162163 , -152.027023 ,mOhm
Freq: 1.247089 (real, image) = ,-206.896545 , 567.241394 ,mOhm
Freq: 1.555230 (real, image) = ,261.538452 , 157.692307 ,mOhm
Freq: 1.939510 (real, image) = ,-63.793106 , -284.482758 ,mOhm
Freq: 2.418741 (real, image) = ,15.000001 , 45.000000 ,mOhm
Freq: 3.016385 (real, image) = ,-46.153847 , 5.769231 ,mOhm
Freq: 3.761699 (real, image) = ,115.000000 , -45.000000 ,mOhm
Freq: 4.691173 (real, image) = ,-94.000000 , 12.000000 ,mOhm
Freq: 5.850308 (real, image) = ,-115.000000 , -205.000000 ,mOhm
Freq: 7.295854 (real, image) = ,-14.705883 , -41.176472 ,mOhm
Freq: 9.098577 (real, image) = ,-266.666687 , 133.333344 ,mOhm
Freq: 11.346732 (real, image) = ,-29.039303 , -7.205240 ,mOhm
Freq: 14.150382 (real, image) = ,-7.692308 , 88.461533 ,mOhm
Freq: 17.646782 (real, image) = ,0.000000 , -50.000000 ,mOhm
Freq: 22.007103 (real, image) = ,50.000000 , -50.000000 ,mOhm
Freq: 27.444809 (real, image) = ,-134.615387 , 273.076904 ,mOhm
Freq: 34.226112 (real, image) = ,50.000000 , -50.000000 ,mOhm
Freq: 42.682995 (real, image) = ,66.666672 , 0.000000 ,mOhm
Freq: 53.229485 (real, image) = ,46.341465 , -17.073172 ,mOhm
Freq: 66.381889 (real, image) = ,33.823528 , 39.705883 ,mOhm
Freq: 82.784103 (real, image) = ,66.666672 , -8.333334 ,mOhm
Freq: 103.239120 (real, image) = ,75.000000 , -275.000000 ,mOhm
Freq: 128.748337 (real, image) = ,-9.756097 , -12.195122 ,mOhm
Freq: 160.560593 (real, image) = ,0.000000 , 100.000000 ,mOhm
Freq: 200.233307 (real, image) = ,102.439026 , 28.048780 ,mOhm
Freq: 249.708694 (real, image) = ,66.853935 , -26.966291 ,mOhm
Freq: 311.408905 (real, image) = ,-200.000000 , 150.000000 ,mOhm
Freq: 388.354523 (real, image) = ,0.000000 , 30.000002 ,mOhm
Freq: 484.312531 (real, image) = ,-10.955056 , -47.471912 ,mOhm
Freq: 603.980713 (real, image) = ,41.176472 , 14.705883 ,mOhm
Freq: 753.217529 (real, image) = ,-68.918922 , 63.513512 ,mOhm
Freq: 939.329041 (real, image) = ,-73.076920 , 15.384616 ,mOhm
Freq: 1171.426636 (real, image) = ,-1.621622 , -30.270269 ,mOhm
Freq: 1460.872925 (real, image) = ,-72.602737 , 60.273975 ,mOhm
Freq: 1821.838135 (real, image) = ,92.920349 , -6.194690 ,mOhm
Freq: 2271.993896 (real, image) = ,-31.034481 , 222.413803 ,mOhm
Freq: 2833.377930 (real, image) = ,-12.500000 , -25.000000 ,mOhm
Freq: 3533.473633 (real, image) = ,3.503185 , -1.910828 ,mOhm
Freq: 4406.554688 (real, image) = ,-27.358490 , 20.754717 ,mOhm
Freq: 5495.364746 (real, image) = ,-110.000000 , -180.000000 ,mOhm
Freq: 6853.207520 (real, image) = ,55.882351 , 26.470589 ,mOhm
Freq: 8546.557617 (real, image) = ,-60.000004 , 30.000002 ,mOhm
Freq: 10658.315430 (real, image) = ,-63.414635 , 20.731707 ,mOhm
Freq: 13291.865234 (real, image) = ,6.234414 , 24.688280 ,mOhm
Freq: 16576.134766 (real, image) = ,150.000000 , 50.000000 ,mOhm
Freq: 20671.910156 (real, image) = ,25.000000 , 25.000000 ,mOhm
Freq: 25779.707031 (real, image) = ,58.620689 , 3.448276 ,mOhm
Freq: 32149.580078 (real, image) = ,-38.461540 , 7.692308 ,mOhm
Freq: 40093.378906 (real, image) = ,13.461539 , 17.307693 ,mOhm
Freq: 50000.000000 (real, image) = ,39.285713 , 32.142857 ,mOhm


Here are the settings :

AppBATCfg_Type *pBATCfg;

AppBATGetCfg(&pBATCfg);
pBATCfg->SeqStartAddr = 0;
pBATCfg->MaxSeqLen = 512;
pBATCfg->RcalVal = 50.0; /* Value of RCAL on EVAL-AD5941BATZ board is 50mOhm */
pBATCfg->ACVoltPP = 300.0f; /* Pk-pk amplitude is 300mV */
pBATCfg->DCVolt = 1200.0f; /* Offset voltage of 1.2V*/
pBATCfg->DftNum = DFTNUM_8192;

pBATCfg->FifoThresh = 2; /* 2 results in FIFO, real and imaginary part. */

pBATCfg->SinFreq = 200; /* Sin wave frequency. THis value has no effect if sweep is enabled */

pBATCfg->SweepCfg.SweepEn = bTRUE; /* Set to bTRUE to enable sweep function */
pBATCfg->SweepCfg.SweepStart = 1.0f; /* Start sweep at 1Hz */
pBATCfg->SweepCfg.SweepStop = 50000.0f; /* Finish sweep at 1000Hz */
pBATCfg->SweepCfg.SweepPoints = 50; /* 100 frequencies in the sweep */
pBATCfg->SweepCfg.SweepLog = bTRUE; /* Set to bTRUE to use LOG scale. Set bFALSE to use linear scale */

When I check the excitation signal after a reset, it goes out after 9 seconds. For what? If the measurements are made without the excitation, normally they will be wrong. Do you know what can cause this error?

Thanks in advance.

Parents Reply Children
  • Hello, we have switched to the AD5940/41ELCZ kit and we have had good results with EIS by modifying the code a little for inconsistencies in the AppIMPCheckFreq function at the level of the predefined gains and some parameters between 1Hz and 200KHz and with noise between 0.1Hz and 1Hz. As soon as possible we will switch back to the BATZ version to continue the tests with the acquired knowledge.