ADS8201 iRGE. Most significant bit erroneus

Antti Martikainen

Other Parts Discussed in Thread: ADS8201

When the input voltage is crossing the 2,5V with a sine wave signal, see the picture below. If the sine wave is all the time below or above the 2,5V, there is no spikes visible. Is the problem in the communication?

5V, 5V with a sine wave signal, ADS8201 iRGE. Most significant bit erroneus, see the picture below. If the sine wave is all the time below or above the 2, there is no spikes visible. Is the problem in the communication or configuration with the converter? Antti Martikainen, when the input voltage is crossing the 2

over 12 years ago

0 Tom Hendrick over 12 years ago

TI__Guru**** 176331 points

Hi Antti,

Welcome to the e2e forum! Can you post a similar screen shot with a full scale input? What processor are you using to communicate with the ADS8201?

0 Antti Martikainen over 12 years ago

Prodigy 40 points

Hi,

Here is the picture with a higher voltage. We are using Renesas H8SX1657 microcontroller in this application.

Regards,

Antti Martikainen

0 Tom Hendrick over 12 years ago in reply to Antti Martikainen

TI__Guru**** 176331 points

Hi Antti,

This is a bit strange - not what I was expecting to see... The picture you sent has five peaks/spikes and the interesting thing to me is that the second spike looks like it would be the correct data point if it were in the first position. Similarly, the forth looks like it would belong in the third spot. Can you post the actual content of that data array so we can get a better idea of the conversion results associated with the excursions?

0 Antti Martikainen over 12 years ago in reply to Tom Hendrick

Prodigy 40 points

Hi Tom,

The Hex data is below. At the moment I do not know the reason for this phenomenon. Might be something in the communication between the controller and AD converter. All the (three) prototype boards have the same phenomenon.

Regards,
Antti

EE30
F130
F3E0
F5E0
F790
F8E0
F9E0
FAC0
FB30
FBF0
FC40
FCA0
FCB0
FC20
FB60
FA40
F8C0
F6F0
F4A0
F240
EF70
EC70
E950
E5C0
E210
DE20
D9F0
D5D0
D150
CCE0
C830
C370
FEA0
B9B0
B500
AFF0
AB30
A630
A150
9CA0
97C0
9360
8EE0
8A90
8670
8280
BEB0
7B30
77D0
74D0
71F0
6F60
6D10
6B00
6940
67D0
66B0
65D0
6540
6510
6520
6590
6650
6750
68B0
6A70
6C60
6EB0
7120
7400
7700
7A40
7DD0
41A0
85A0
89C0
8E00
9280
96E0
9BC0
A080
A540
AA40
AF00
B400
B900
BDE0
82B0
C770
CC10
D0B0
D510
D970
DDA0
E190
E560
E8C0
EC40
EF50
F220
F490
F680
F7E0
F930
FA30
FB00
FB70
FC20
FC60
FC90
FCA0
FC10
FB30
F9C0
F840
F650
F3E0
F180
EEB0
EB80

0 Antti Martikainen over 12 years ago in reply to Antti Martikainen

Prodigy 40 points

Hi Tom.

The problem has been solved now.

The reason to the spikes was the addressing of the configuration registers. The converter started to operate correctly, when we added chip select controls (up and down) between the configuration control addressing.

Regards,
Antti

0 Tom Hendrick over 12 years ago in reply to Antti Martikainen

TI__Guru**** 176331 points

Great news! Thank you for letting us know!

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ADS8201 iRGE. Most significant bit erroneus