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ADS131A04: Construction of write/read a command for multiple devices

PeteBux
Prodigy 80 points
Part Number: ADS131A04

Hi,

We're working on a design with 2 x ADS131A04, first device in Asynchronous Interrupt mode (M0 = Vdd), the second in synchronous slave mode (\DONE of dev1 as \CS of dev2, M0 is floating), this according to the datasheet SBAS590D. The device word length has been set to 32 bit (M1 = Vdd for both devices).

It is however not clear how to access the second device when writing e.g. the unlock command. Do we need to send 4 bytes = 0x06550000 to unlock both or 8 bytes 0x0655000006550000 or otherwise?

I'm only trying to understand how to access the device correctly.

With best regards,

Pieter

  • 0
    TI__Guru 57296 points

    Hi Pieter,

    Thanks for your post and welcome to our forum!

    You can treat the devices as one and place the communication words one after another. To the host, this appears as a single, extended frame. The /CS line from the microcontroller (/CS(1) below) will remain low until you are done communicating with both ADS131A04 devices. The interface in the ADS131A04 is smart enough to know the required frame size for each device based on the command you send. In this manner, you are able to send one command to Device 1 and a different command to Device 2, even if those commands require a different number of words. The /DONE pin of Device 1 (/DONE(1)) is asserted when the first frame is finished. This will immediately assert the /CS pin on Device 2. When /DONE(1) is low, the interface for Device 1 is disabled, even while /CS(1) remains low.

    Figure 97 illustrates the relationship between communication words for multiple devices in a single frame. MSB(2) would normally be the first bit of the first word in the frame that you send to Device 2.

    Best Regards,