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ADS1255: Example 2-wire configuration with UART in serial mode 0

Giovanni Vitale
Prodigy 10 points

Part Number: ADS1255

Tool/software:

Dear Texas Instruments,

I am currently using the ADS1255 for small projects with the SPI port and the Teensy 4.1. It works perfectly, and I am able to fully exploit its capabilities.

However, I am now working on a 12-channel acquisition system. Managing 12 ADS1255 devices with a single microcontroller is becoming challenging.

Therefore, I would like to configure the ADS1255 in a 2-wire mode and use UART to read the data.

Considering the capabilities of the Teensy 4.1, it seems much simpler to manage multiple ADS1255 devices in this mode, or at least I would like to test it to assess whether it is a feasible solution for my project.

Unfortunately, there is not much explanation in the datasheet regarding this 2-wire UART mode. Could you provide me with more details? Is there any code or pseudocode you can provide as a starting point?

I have currently performed some tests and I am only reading 0. I have tried using different baud rates, but the result does not change. When connecting the device with a serial adapter, I don't receive anything.

RESET, PWDN, and Chip Select are correctly connected to 3.3V, 3.3V, and GND respectively. DIN and DOUT are shorted and connected to the RX of the microcontroller. SCK is connected to the TX of the microcontroller.

The DRDY pin is low, indicating that the conversion is complete.

Thank you for your availability.

Best regards,


Giovanni

  • 0
    TI__Guru 56611 points

    Hi Giovanni Vitale,

    How are you planning on controlling multiple devices if the CS is low for all chips and they all send data at the same time?

    You either need multiple CS lines or multiple DOUT lines to control multiple devices. This cannot be achieved with a single UART interface

    -Bryan

  • 0 in reply to Bryan Lizon86
    Prodigy 10 points

    Dear Bryan,

    Currently, I am testing a single ADS1255. Therefore, the raised issue does not apply. If I manage to make it work in two-wire mode with a UART, I will use the 8 serial ports of the Teensy 4.1 and declare another 4 software ones. This way, I will have the 12 channels I need. The Teensy 4.1 will then allow me to transmit the data over Ethernet using the TCP/IP protocol or simply via the dedicated serial interface to the PC.

    Giovanni 

  • 0 in reply to Giovanni Vitale
    TI__Guru 56611 points

    Hi Giovanni Vitale,

    Can you provide logic analyzer data showing the communication to and from the ADC? Please provide both signals (RX and TX)

    Please also share a schematic

    -Bryan