ADS1282EVM-PDK connected to a SM24 geophone

Hi Chris,

Thank you for the quick response.

-For a budget lab, is a simple pc power supply sufficent to use as the only power supply for the +10V, -10V, +5V, -5V and the 3.3V for a precision ADC such as the ADS1282 (ADS1282EVM-PDK)?

-For a standalone solution, is it possible to have all these voltages from a single battery or is it more efficient to use 2 different batterys, one just above 10V and a second just above 5V? Would it be more efficient for the voltage regulators or is it just over complicating things?

-A question on the ADCPro sw, is it possible to have it setup so that it waits until a certain preset threshold is reached before actually begins to record data?

-Can the geophone generate such high voltage that the ADS1282EVM-PDK is damaged or is there protection ciruit on the ADS1282EVM-PDK?

-Need to doublecheck your response on the biasing, are you talking about connecting resistors as is shown in the schematics for the ADS1282 Application Information in figure 65, that is resistors R5(20K) and R6(20K)?
So there is no need for the rest of the passive components between the geophone and the ADS1282 in figure 65 if the resistors R5 and R6 are applied to the J6 header, perhaps it is equivalent to the OPA1632 part of the ADS1282EVM-PDK?
And when you suggest the solution of adding resistors to the J6 header you are not talking about removing the OPA1632, as I understood it that was another solution which would mean to use all the passive components just as in figure 65?

-What about the CAPP and the CANN, comparing figure 65 to the ADS1282EVM-PDK there is a few differences regarding CAPP and CANN, can the ADS1282EVM-PDK be connected to a geophone wihout any modification in this case?

-For the VREFN and VREFP in figure 65, will we get the same VREFN and VREFP from the standard setup of the ADS1282EVM-PDK as described in the manual?

My work is mainly with embedded sw but I am hoping to learn a lot about reading sensor data with the help of the ADS1282EVM-PDK, this forum is much appreciated.

Best Regards,
Johan

Hi Johan,

Johan Bergman said:

-For a budget lab, is a simple pc power supply sufficent to use as the only power supply for the +10V, -10V, +5V, -5V and the 3.3V for a precision ADC such as the ADS1282 (ADS1282EVM-PDK)?

It would depend on the supply...USB power is usually not an accurate and clean 5V. Switching power supplies are required to generate the other supplies rails. The various supply rails are usually then cleaned up by LDOs. If LDOs with good PSRR performance are used, then yes, you could achieve good performance!

 

Johan Bergman said:

-For a standalone solution, is it possible to have all these voltages from a single battery or is it more efficient to use 2 different batterys, one just above 10V and a second just above 5V? Would it be more efficient for the voltage regulators or is it just over complicating things?

This is not my area of expertise. I think it is certainly possible to generate all of the supply rails from a single battery. My intuition would say that this may be more efficient since batteries are generally bulky.

Note: That the +/- 10V supplies for the ADS1282EVM are only required to power the instrumentation amplifiers. If you remove them, the EVM will likely work without the +/-10V supplies.

 

Johan Bergman said:

-A question on the ADCPro sw, is it possible to have it setup so that it waits until a certain preset threshold is reached before actually begins to record data?

No, the EVM and ADCPro are only designed to show off performance of the ADC. You would need to write your own firmware to do something like that.

 

Johan Bergman said:

-Can the geophone generate such high voltage that the ADS1282EVM-PDK is damaged or is there protection ciruit on the ADS1282EVM-PDK?

Certainly this is a risk. There are some basic clamping diodes on the EVM to help protect the ADS1282, but this is something you'll need to evaluate. The EVM is just to evaluate the performance of the ADC, it is not guaranteed or recommended to used in the end-application.

 

Johan Bergman said:

-Need to doublecheck your response on the biasing, are you talking about connecting resistors as is shown in the schematics for the ADS1282 Application Information in figure 65, that is resistors R5(20K) and R6(20K)?
So there is no need for the rest of the passive components between the geophone and the ADS1282 in figure 65 if the resistors R5 and R6 are applied to the J6 header, perhaps it is equivalent to the OPA1632 part of the ADS1282EVM-PDK?
And when you suggest the solution of adding resistors to the J6 header you are not talking about removing the OPA1632, as I understood it that was another solution which would mean to use all the passive components just as in figure 65?

Yes, I was referring to adding biasing resistors much like R5 and R6, in the example application. There may still be a need for other passive components to provide input protection and input filtering. The OPA1632 can still be removed!

 

Johan Bergman said:

-What about the CAPP and the CANN, comparing figure 65 to the ADS1282EVM-PDK there is a few differences regarding CAPP and CANN, can the ADS1282EVM-PDK be connected to a geophone wihout any modification in this case?

Refer to pages 13 and 16 in the ADS1282 datasheet about idle tones. The circuit in Figure 70 (or Figure 65 as I think you've been referring to?) is an optional way of handling the tone.

 

Johan Bergman said:

-For the VREFN and VREFP in figure 65, will we get the same VREFN and VREFP from the standard setup of the ADS1282EVM-PDK as described in the manual?

If you're referring to the OPA227 on the ADS1282EVM, it is not required to buffer the REF5050 reference. The REF5050 is capable of driving the ADS1282 reference inputs directly. Other references may require an additional buffer, but the REF5050 is buffered internally.

 

Best Regards,
Chris

Hi Chris,

For me to be able to start recording the geophone data and to do this with a minimum of modification to the  ADS1282EVM-PDK have I understood you correctly that by only adding the R5 and R6 resistors to the J6 header as we have talked about, that this would be a meaningful starting point as to get quality readings from a geophone?

Or do you strongly suggest removing the OPA1632 and the passive components that goes with the OPA1632 on the  ADS1282EVM-PDK?

These more detailed modifications as far as I understand would be done to make the schematics as close as possible to the figure 65 in the datasheet for ADS1282?

Regarding the clamping diodes that protect the ADS1282, could you suggest a specification for these that would protect the ADS1282 from possible overload by the geophone or would it require a more intricate schematics all together, in that case is there a TI reference design for that?

Best Regards,

Johan

Hi,

I have finally connected a geophone and the external power supply and bipolar powersupply to the ADS1282EVM-PDK. But I can not get any samples readings. I can see that the ADC Pro shows that it is connected to the ADS1282 and I can make settings but when I hit the Acquire button it does not start acquiring the 2048 samples.

I can see in the error log that it shows error:

Error Code 1055:  To More Specific Class in libadcpro.lvlib:sigValInCluster.vi->libadcpro.lvlib:SignalPlugin.lvclass:setPointsAcquired.vi->libadcpro.lvlib:SignalPlugin.lvclass:acquire.vi->Shell - Main.vi

Any input appreciated.

Best Regards,

Johan

Johan,


I've never seen this error code before, so I've sent a note to someone that might have an answer. Chris is out of the office for a little bit, so it may take time to get an answer.

Just to be sure, what version of ADCPro and plugin are you using? What version of windows are you running?


Joseph Wu

Hi Joseph,

I am running Windows 8.1.
Plugin: ads1282-adcproplugin-2.0.0.exe
ADCPro: Below from About ADCPro popup:
ADCPro version 2.0.1build4
EVM: version 0.0.0.0
Test: Version 0.0.0.

I had some problems following the user guide to get the device drivers installed in windows 8.1.
Finally got the idea to try and get windows to accept third party unsigned drivers, but even then it was
a bit tricky, had to locate the drivers and go to the device and update driver manually.

Also one thing which is unclear , in the user guide it is stated in section 9.4 to set J4 low to indicate that EVM board is an ADS1282EVM, if you could please clarify this.
There is one section on the ADS1282EVM where J4 is printed but it is only an empty slot with 2 of the 3 holes soldered a connection, from the middle position to a position named 82, I guess this is actually what is mentioned, that this is the J4 is already set to low from the factory.

When can I expect to get an answer from Chris, I am really excited to start seeing some measurements and start to learn about geophone readings using TI ADC.

Best Regards,
Johan

Hi,

Just made another attempt after my latest reply just this morning, of course it started to work, only thing I can imagine is windows needed another reboot.
I see the most wonderful graphs, unbelievably detailed geophone graphs.
This is exciting.
Is it possible to setup the ADCPro to only start recording the acquire once it has a sample above a certain threshold?
This is the way it will work once I get my own solution up and running of course, just that it would be nice if ADCPro could be set to work like that. I guess one way to get something like that is to have a script running which looks at the auto files and deletes any which are filled with very low sample values...

Best Regards,
Johan

Hi,

Is there any example code for the ADS1282-EVM to use it standalone on arduino?

I have successfully tried to use a simple 12 bit ADC which communicates over SPI to the arduino and found code which does bitbanging to communicate over SPI.

Looking at the datasheet for ADS1282 I wonder if it is possible to tweak the arduino code for bitbanging over SPI to the ADS1282 or if it should be done over I2C?

Any info on any example code on how to communicate with the ADS1282-EVM as a standalone piece towards a microcontroller would be appreciated in case there is none for the arduino that you know of.

I plan to work towards creating a fully functioning vibration measurement system and also need to know if the ads1282 is the way to go for a proffessional battery operated geophone blast vibration measurement system? If it needs to be a 3 channel geophone system, which configuration of ADS1282 would be most suitable?

Best Regards,

Johan

Hi Johan,

We don't have example code specific to the ADS1282 and most of our example code is for TI-based processors. However, there is a third-party project on GitHub with example code for an Arduino, found here:

Again it's not ADS1282 specific, but the code won't be too different as the SPI interfaces for the ADS1248 and ADS1256 devices are similar.

The ADS1282 uses a SPI (it's not I2C compatible) and is certainly the device I would recommend for interfacing to a geophone. Typically, a 3-channel geophone system would use 3x ADS1282s.

Best Regards,
Chris