AD5933
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The AD5933 is a high precision impedance converter system solution that combines an on-board frequency generator with a 12-bit, 1 MSPS, analog-to-digital...
Datasheet
AD5933 on Analog.com
Hello,
im pretty new in programming IC's so please excuse my mistakes if they are dumb. So i use a Raspberry Pi for the communication and my code is in Python. My problem is i always keep getting 0x60, 0x66 in the Status Register which makes no sense. Just sometimes i get 0x62 which should indicate valid real/img data. As a result my measurements are wrong. I can show you my code maybe there are some mistakes
import smbus
import math
bus = smbus.SMBus(1)
ADRESSE = 0x0D
j=0
x=0
#Startfrequency
bus.write_byte_data(ADRESSE, 0x82, 0x07) #051EB8 @10khz #028F5C @5khz
bus.write_byte_data(ADRESSE, 0x83, 0xAE) #0F5C28 @30khz #07AE14 @15 khZ
bus.write_byte_data(ADRESSE, 0x84, 0x14) #199999 @50khz #0CCCCC @25khz
#Frequency increment
bus.write_byte_data(ADRESSE, 0x85, 0x00) #00014F @10hz
bus.write_byte_data(ADRESSE, 0x86, 0x41) #004189 @500hz
bus.write_byte_data(ADRESSE, 0x87, 0x89)
#Number of increments
bus.write_byte_data(ADRESSE, 0x88, 0x00)
bus.write_byte_data(ADRESSE, 0x89, 0x96)
#Control Register Settling Time Cycles
bus.write_byte_data(ADRESSE, 0x8A, 0x00)
bus.write_byte_data(ADRESSE, 0x8B, 0x32)
#Control Register Standby Mode
bus.write_byte_data(ADRESSE, 0x80,bus.read_byte_data(ADRESSE,0x80)&0x07 |0xB0)
#Control Register Initialiaze with start frequency
bus.write_byte_data(ADRESSE, 0x80, bus.read_byte_data(ADRESSE,0x80)&0x07 |0x10)
#Control Register Start Frequency Sweep
bus.write_byte_data(ADRESSE, 0x80, bus.read_byte_data(ADRESSE,0x80)&0x07 |0x20)
#Control Register Increment Frequency
bus.write_byte_data(ADRESSE, 0x80, bus.read_byte_data(ADRESSE,0x80)&0x07 |0x31)
bus.write_byte_data(ADRESSE, 0x81, bus.read_byte_data(ADRESSE,0x80)&0x07 |0x00)
while x<8000:
status = bus.read_byte_data(ADRESSE,0x8F)
if status==0x62:
real1= bus.read_byte_data(ADRESSE, 0x94)
real2= bus.read_byte_data(ADRESSE, 0x95)
imag1= bus.read_byte_data(ADRESSE, 0x96)
imag2= bus.read_byte_data(ADRESSE, 0x97)
r= (real1*256)+real2
i= (imag1*256)+imag2
#Magnitude Calculation
b=math.sqrt((r**2)+(i**2))
#Gain Factior
c=4.62e-11 #515.819e-12 #5.39e-11#6.93e-11
#Impedance Calculation
z=1/(b*c)
print (z)
print (r)
print ( i)
print (status)
break
if status!=0x62:
bus.write_byte_data(ADRESSE, 0x80,bus.read_byte_data(ADRESSE,0x80)&0x07 | 0x30)
print(status)
x=x+1
Hey,
yea i've already read the application note but didnt really help. I am not sure what is really wrong now. Maybe there is something wrong with my circuit.
Meanwhile i've changed my Code a little bit and now the imaginary Datas are pretty good. So they are not around 5 anymore and real data isnt also around 65k.
import smbus
import math
START_FREQ_1=0x82
START_FREQ_2=0x83
START_FREQ_3=0x84
FREQ_INC_1=0x85
FREQ_INC_2=0x86
FREQ_INC_3=0x87
NUM_FREQ_1=0x88
NUM_FREQ_2=0x89
SETTL_CYCL_1=0x8A
SETTL_CYCL_2=0x8B
CNTRL_1=0x80
CNTRL_2=0x81
STATUS_REG=0x8F
TEMP_1=0x92
TEMP_2=0x93
REAL_1=0x94
REAL_2=0x95
IMAG_1=0x96
IMAG_2=0x97
bus = smbus.SMBus(1)
ADRESSE = 0x0d
j=0
x=0
c=0
q=0
#Startfrequency
bus.write_byte_data(ADRESSE, START_FREQ_1, 0x0E)#051EB8 @10khz #028F5C @5khz #0EA645 @30khz (16,776mhz)
bus.write_byte_data(ADRESSE, START_FREQ_2, 0xA6)#0F5C28 @30khz #07AE14 @15 khZ #075322 @ 15khz (16,776mhz)
bus.write_byte_data(ADRESSE, START_FREQ_3, 0x45)#199999 @50khz #0CCCCC @25khz
#Frequency increment
bus.write_byte_data(ADRESSE, FREQ_INC_1, 0x00)#00014F @10hz #000140 @10hz(16,776mhz)
bus.write_byte_data(ADRESSE, FREQ_INC_2, 0x01)#004189 @500hz #003E81 @500hz (16,776mhz)
bus.write_byte_data(ADRESSE, FREQ_INC_3, 0x40)
#Number of increments
bus.write_byte_data(ADRESSE, NUM_FREQ_1, 0x01)#0096 @ 150
bus.write_byte_data(ADRESSE, NUM_FREQ_2, 0xff)#01FF @ 511
#Control Register Settling Time Cycles
bus.write_byte_data(ADRESSE, SETTL_CYCL_1, 0x00)
bus.write_byte_data(ADRESSE, SETTL_CYCL_2, 0x0F)
#Control Register Standby Mode
bus.write_byte_data(ADRESSE, CNTRL_1,bus.read_byte_data(ADRESSE,CNTRL_1)&0x07 |0xB0)
#Control Register Initialiaze with start frequency
bus.write_byte_data(ADRESSE, CNTRL_1, bus.read_byte_data(ADRESSE,CNTRL_1)&0x07 |0x10)
while x<10000:
x=x+1
#Control Register Start Frequency Sweep
bus.write_byte_data(ADRESSE, CNTRL_1,bus.read_byte_data(ADRESSE,CNTRL_1)&0x07 |0x20)
status=bus.read_byte_data(ADRESSE,STATUS_REG)
while (bus.read_byte_data(ADRESSE,STATUS_REG)&0x07)<4:
status=bus.read_byte_data(ADRESSE,STATUS_REG)
while (bus.read_byte_data(ADRESSE,STATUS_REG)&0x02)==0:
bus.read_byte_data(ADRESSE,STATUS_REG)
flag=bus.read_byte_data(ADRESSE,STATUS_REG)&2
flag2=bus.read_byte_data(ADRESSE,STATUS_REG)&4
if (flag==2)&(flag2!=4):
real1= bus.read_byte_data(ADRESSE, REAL_1)
real2= bus.read_byte_data(ADRESSE, REAL_2)
imag1= bus.read_byte_data(ADRESSE, IMAG_1)
imag2= bus.read_byte_data(ADRESSE, IMAG_2)
#Temp
bus.write_byte_data(ADRESSE, CNTRL_1, bus.read_byte_data(ADRESSE,CNTRL_1)&0x07 |0x90)
f=bus.read_byte_data(ADRESSE, TEMP_1)
g=bus.read_byte_data(ADRESSE, TEMP_2)
h=(f*256)+g
if h<8192:
h=h/32
else:
h=h-16384
h=h/32
r= (real1*256)+real2
i= (imag1*256)+imag2
#Magnitude Calculation
b=math.sqrt((r**2)+(i**2))
#Gain Factior
c=1.0756009e-10 #8.04780e-11
#Impedance Calculation
z=1/(b*c)
print '******************'
print '|Z|=',int (z), 'Ohm'
print 'RE:',r
print 'IM:',i
print 'Temp:', int (h), 'Grad'
print 'Status Reg:',bus.read_byte_data(ADRESSE,STATUS_REG)
print '******************'
if flag2==4:
real1= bus.read_byte_data(ADRESSE, REAL_1)
real2= bus.read_byte_data(ADRESSE, REAL_2)
imag1= bus.read_byte_data(ADRESSE, IMAG_1)
imag2= bus.read_byte_data(ADRESSE, IMAG_2)
#Temp
bus.write_byte_data(ADRESSE, CNTRL_1, bus.read_byte_data(ADRESSE,CNTRL_1)&0x07 |0x90)
f=bus.read_byte_data(ADRESSE, TEMP_1)
g=bus.read_byte_data(ADRESSE, TEMP_2)
h=(f*256)+g
if h<8192:
h=h/32
else:
h=h-16384
h=h/32
r= (real1*256)+real2
i= (imag1*256)+imag2
#Magnitude Calculation
b=math.sqrt((r**2)+(i**2))
#Gain Factior
c=1.0756009e-10 #8.04780e-11
#Impedance Calculation
z=1/(b*c)
print '******************'
print 'RESULT'
print '|Z|=',int (z), 'Ohm'
print 'RE:',r
print 'IM:',i
print 'Temp:', int (h), 'Grad'
print 'Status Reg:',bus.read_byte_data(ADRESSE,STATUS_REG)
print '******************'
break
if (bus.read_byte_data(ADRESSE,STATUS_REG)&0x07)<4:
bus.read_byte_data(ADRESSE, REAL_1)
bus.read_byte_data(ADRESSE, REAL_2)
bus.read_byte_data(ADRESSE, IMAG_1)
bus.read_byte_data(ADRESSE, IMAG_2)
bus.write_byte_data(ADRESSE, CNTRL_1,bus.read_byte_data(ADRESSE,CNTRL_1)&0x07 | 0x30)
#Shut Down
bus.write_byte_data(ADRESSE, CNTRL_1,bus.read_byte_data(ADRESSE,CNTRL_1)&0x07 | 0xA0)
I've now made the Circuit with AFE so with the OP amps as described in CN-0217. When i setup the start frequency at 30k it gives me RE/IM Data around 65k. But when i start at 250 Hz and go up with 10 Hz Steps i get these results
As you see the RE Data jumps to 65k at 1280 Hz and goes back to "normal" at around 2300 Hz.
So for certain frequencies it keeps giving me 65k and i dont know why. I've also tried it with different low frequencies but it's the same. At some point it always jumps to 65k.
