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ADS1261EVM: ADS1261EVM: Interfacing with external micro controller, Measuring the single ended inputs

Ram Ch
Prodigy 120 points

Part Number: ADS1261EVM
Other Parts Discussed in Thread: ADS1261

Hello,

I am using ADS1261EVM board, able to perform register read/write operation using the Delta-Sigma ADC Evaluation software GUI. I have below questions while working on the EVM, please help me with answers.

1) How to measure single ended inputs? 2.5 Volts is given to AIN0 and wanted to measure this, AIN1 is connected to ground. I have selected AIN0 and AIN1 in MUXP and MUXN of INPMUX register. I selected AVDD (5V) , AVSS (0V) as default positive and negative reference inputs respectively and internal reference is disabled via REF register.  Below is the ADC output.

I am not sure if above ADC count is correct or not. What are the ADC Conversion Data Codes for single ended measurements? Generally, what should be selected in MUXP and MUXN of INPMUX register for single ended input measurements?

2) We wanted to Interface EVM with external micro-controller. Do we need to bypass the on-board processor using Jumper JP1 for establishing the communication with external micro-controller? 

Thanks, 

Ram

  • 0
    TI__Guru 58971 points

    Hi Ram,

    For #1: You can use our calculator tool to help you understand how the output codes translate to a voltage: https://www.ti.com/lit/zip/sbac200

    When I put this value into the calculator tool using a 5V reference voltage, the output was 2.51 V. So the device is measuring your inputs correctly. Please note that in order to measure ground-referenced input signals using a unipolar supply with the ADS1261, the PGA must be disabled.

    For #2: yes, you can use an external MCU by installing jumper J1. Please ensure that you have a strong ground connection between the two boards, otherwise you might see noise on your digital communication lines.

    -Bryan