ADS1263EVM-PDK: How to use it to sample acceleration sensor data

Hi Mohamed,

The pdf document you provided is for 441A101 and it is not helpful to understand the 442A101 sensor module. I found the material for 442A101 module shown in page 25-27. This material is simple and does not show the details including the structure inside module, it only shows the following information:

• Sensor Excitation Voltage:   24+/-0.5V
• Sensor Excitation Current:  1-20mA (normally 4mA)
• Output Range:  >+/-10V
• Output Impedance:  100+/-10%ohms

Based on these limited information, the 24V excitation voltage cannot be used as a reference to the ADC and the ADC cannot directly provide a 4mA excitation currents to the sensor module. Also, the output (>+/-10V) from the module is too high to sample for the ADC. I did not use this sensor module, however it looks like this module already has integrated a gain buffer amplifier to support up to x100 gain. You might have to check all these details with the sensor module manufacturer, then I can recommend a proper ADC to you.

For ADXL354 MEMS accelerometer, I do not see a pin which can be used as a reference voltage to the ADC, and there is no output signal which is directly proportional to the magnitude of an excitation voltage or current.

Best regards,

Dale

Hi Dale,

Thanks for your reply. The information you provided is correct because I checked them using a multimeter about the source excitation and output. What I think might be important to know that the module, as you said, has an integrated gain amplifier with three options x1, x10, and x100. When I change the gain, I can reach 1V signal or smaller but this I guess does not help with digitize the signal. I hope you can recommend me something to do or try. For the ADXL354, here is a link for the sensor . On page 22, I think the pin V1P8ANA can be used as a reference voltage or? my first circuit to sample the data from the sensor is to connect the V1p8ana to AIN2 as a reference voltage with respect to AVSS (can be chosen from ADCpro), then connect the XOUT for example to AIN 1 and from the program to choose AINP1 as AIN1 signal and AINCOM as AINN1. Is that correct? or I need to modify something? and how to check if it is correct if you have an idea?

Thanks!

I think it might be a good idea to add this link for the piezosensor.
www.pcb.com/products

Hi Mohamed,

For the ADSXL354, yes, the V1P8ANA can be used as a reference to the ADC since the output of ADXL354 is ratiometric to the voltage of this pin.Thanks for clarification.

For the 442A101 sensor module, I really do not know how it works internally without more information.The material for 442A101 specifies the output is >+/-10V. If the signal from the sensor is not small, you do not need a ADC with higher internal gain. Hence, to be simple, you have to confirm your actual signal range from the sensor module, also confirm if you will use an excitation voltage or current for the module and what the voltage or current level, then can determine which ADC can be used and how to connect the module to the ADC.

Regarding your questions to the connections, we do have reference designs to show different connections, please see them below:

High-Resolution, Low-Drift, Precision Weigh-Scale Reference Design with AC Bridge Excitation

Using the ADS1261's Integrated AC Excitation Mode to Remove System Offset and Offset Drift

Best regards,

Dale

Hi Dale,

I have a stupid question. In the program, when I have a single ended signal (like XOUT from ADSXL354), should I choose it as a AINP and leave the AINN empty or should I just use the ANICOM?

Hi Mohamed,

No worries. You can use any pins as AINP, the configuration depends on your signal type, please see the circuits for single-ended input below which is shown in Figure 158 of datasheet:

Best regards,

Dale