AD5940

Hi,

You may refer to 

(+) How to change AD5940's sampling frequency - Q&A - Precision Microcontrollers - EngineerZone (analog.com)

Hi,

If I want to collect impedance data at a frequency of 1000hz,what  should I do?

thanks.

Hi,

In the function below, 

static AD5940Err AppBIASeqMeasureGen(void)
{
AD5940Err error = AD5940ERR_OK;
uint32_t const *pSeqCmd;
uint32_t SeqLen;

uint32_t WaitClks;
SWMatrixCfg_Type sw_cfg;
ClksCalInfo_Type clks_cal;

clks_cal.DataType = DATATYPE_DFT;
clks_cal.DftSrc = AppBIACfg.DftSrc;
clks_cal.DataCount = 1L<<(AppBIACfg.DftNum+2); /* 2^(DFTNUMBER+2) */
clks_cal.ADCSinc2Osr = AppBIACfg.ADCSinc2Osr;
clks_cal.ADCSinc3Osr = AppBIACfg.ADCSinc3Osr;
clks_cal.ADCAvgNum = 0;
clks_cal.RatioSys2AdcClk = AppBIACfg.SysClkFreq/AppBIACfg.AdcClkFreq;
AD5940_ClksCalculate(&clks_cal, &WaitClks);

................

AD5940_ClksCalculate() function calculates the number of clocks required to wait for each sample output.

For ODR =1000Hz, no. of wait clocks allowed between each sample is (16MHz/1000Hz) if system clock frequency = 16Mhz.

Kindly monitor AD5940_ClksCalculate() output and change the config to achieve (16MHz/1000Hz).

Hi,

In the function below, 

static AD5940Err AppBIASeqMeasureGen(void)
{
AD5940Err error = AD5940ERR_OK;
uint32_t const *pSeqCmd;
uint32_t SeqLen;

uint32_t WaitClks;
SWMatrixCfg_Type sw_cfg;
ClksCalInfo_Type clks_cal;

clks_cal.DataType = DATATYPE_DFT;
clks_cal.DftSrc = AppBIACfg.DftSrc;
clks_cal.DataCount = 1L<<(AppBIACfg.DftNum+2); /* 2^(DFTNUMBER+2) */
clks_cal.ADCSinc2Osr = AppBIACfg.ADCSinc2Osr;
clks_cal.ADCSinc3Osr = AppBIACfg.ADCSinc3Osr;
clks_cal.ADCAvgNum = 0;
clks_cal.RatioSys2AdcClk = AppBIACfg.SysClkFreq/AppBIACfg.AdcClkFreq;
AD5940_ClksCalculate(&clks_cal, &WaitClks);

................

AD5940_ClksCalculate() function calculates the number of clocks required to wait for each sample output.

For ODR =1000Hz, no. of wait clocks allowed between each sample is (16MHz/1000Hz) if system clock frequency = 16Mhz.

Kindly monitor AD5940_ClksCalculate() output and change the config to achieve (16MHz/1000Hz).

Akila said:

Kindly monitor AD5940_ClksCalculate() output and change the config to

Thanks，So I just need to change (&WaitClks) to 16MHz/1000Hz?

Hi,

Waitclks will be calculated based on your ADC configuration. You have to change ADC configuration such that derived waitclks = 16MHz/1000Hz