Hi,
I am using AD5940 to conduct SWV measurements and trying to process the measurement data. If I understand it correctly, the data stored in FIFO is the voltage measured at the working electrode and further divided by the RTIA and hence is the current flowing into the working electrode. But I was not sure what should be the corresponding voltage if I am drawing a plot with voltages as the x axis and current as the y axis.
Here is the parameters I am using for SWV measurement:
void AD5940SWVStructInit(void)
{
AppSWVCfg_Type *pRampCfg;
AppSWVGetCfg(&pRampCfg);
/* Step1: configure general parmaters */
pRampCfg->SeqStartAddr = 0x10; /* leave 16 commands for LFOSC calibration. */
pRampCfg->MaxSeqLen = 512-0x10; /* 4kB/4 = 1024 */
pRampCfg->RcalVal = 10000.0; /* 10kOhm RCAL */
pRampCfg->ADCRefVolt = 1.820f; /* The real ADC reference voltage. Measure it from capacitor C12 with DMM. */
pRampCfg->FifoThresh = 1023; /* Maximum value is 2kB/4-1 = 512-1. Set it to higher value to save power. */
pRampCfg->SysClkFreq = 16000000.0f; /* System clock is 16MHz by default */
pRampCfg->LFOSCClkFreq = LFOSCFreq; /* LFOSC frequency */
pRampCfg->AdcPgaGain = ADCPGA_1;
pRampCfg->ADCSinc3Osr = ADCSINC3OSR_4;
/* Step 2:Configure square wave signal parameters */
pRampCfg->RampStartVolt = -500.0f; /* Measurement starts at -0.6V*/
pRampCfg->RampPeakVolt = 0.0f; /* Measurement finishes at 0V */
pRampCfg->VzeroStart = 1300.0f; /* Vzero is voltage on SE0 pin: 1.3V */
pRampCfg->VzeroPeak = 1300.0f; /* Vzero is voltage on SE0 pin: 1.3V */
pRampCfg->Frequency = 60; /* Frequency of square wave in Hz */
pRampCfg->SqrWvAmplitude = 25; /* Amplitude of square wave in mV */
pRampCfg->SqrWvRampIncrement = 5; /* Increment in mV*/
pRampCfg->SampleDelay = 0.2f; /* Time between update DAC and ADC sample. Unit is ms and must be < (1/Frequency)/2 - 0.2*/
pRampCfg->LPTIARtiaSel = LPTIARTIA_24K; /* Maximum current decides RTIA value */
pRampCfg->bRampOneDir = bFALSE; /* Measure ramp in two directions */
}
Thank you!
