ADS1278: Reading data in SPI fixed mode

Prodigy 210 points

Replies: 3

Views: 60

Part Number: ADS1278

Hi,

i want to get data from ADS1278 EVM in SPI mode.

I have used EVM-PDK as power supply and raspberry pi as data extractor, as the picture shows:

I'm sure the hardwares are normal, but i can't capture data from ADS1278EVM.

I think I have errors in wiring or software.

I would like to ask you to provide some comments about it.

Here are all my wiring and settings:

S6 -> turn to SPI

JP4, JP5 -> open circuit

J3.7, J3.8 -> connect photodiode (1channel)

J4.2, J4.6 -> [0,1] High-Resolution

J4.8, J4.12, J4.14 -> [0,0,1] SPI TDM Fixed

J4.1 -> High (SYNC)

J4.19 -> High (CLK)

J4.15 -> start to capture data when voltage falling (DRDY)

J4.3 -> SCLK pin on Rapberry Pi

J4.13 -> MOSI pin on Rapberry Pi

J4.18 -> GND pin on Rapberry Pi

J5.3, J5.5, J5.7, J5.9 -> connect EVM-PDK

But it doesn't work with this setting.

I don't know where is the problem ?

Can you please help me to solve it ? Thank you.

3 Replies

  • Hello,

    Can you take some measurements and verify the signals are getting to the IO pins of the aDS1278?  An oscilloscope or a logic analyzer could be used to verify communications.

    Also, from your above list:

    J4.13 -> MOSI pin on Rapberry Pi

    This is incorrect, and should be connected as shown:

    J4.13 -> MISO pin on Rapberry Pi

    Regards,
    Keith Nicholas
    Precision ADC Applications

  • In reply to Keith Nicholas:

    Hi,

    I use multimeter to ensure that these I/O pins are triggered by  raspberry pi.

    But I still did not capture any signal from the DOUT pin.

    In this state, DOUT pin has no voltage value,

    but it has the voltage value when connected to EVM-PDK.

    I guess i have something unset but i don't know.

    Maybe S1 or S2 should be changed or not ?

    Can you please help me to solve it ? Thank you.

  • In reply to user6263950:

    Hello,

    Make sure your FORMAT pins are set to the correct levels for SPI TDM Fixed:

    FORMAT2 (J4.14)->0

    FORMAT1 (J4.12)->0

    FORMAT0 (J4.8)->1

    Also, MODE pins are set correct levels for High Resolution:

    MODE1 (J4.6)->0

    MODE0 (J4.2)->1

    S1 and S2 should all be set to the OFF condition.

    S6 should be set for SPI mode:

    jumpers installed on [2-3], [5-6], [8-9], [11-12]

    Regards,
    Keith