ADS1293 SPI protocol

Felipe Schneider

Other Parts Discussed in Thread: ADS1293EVM

Hello guys,

I have an ADS1293EVM board, I removed the resistors that connect the MSP to the ADS, so I can use the spi bar to communicate with another microcontroller (which I have more experience and my company have being working with for another projects).

The problem begun when the ADS datasheet (pg. 37, figure 29), presents the SPI protocol and it states that during the 8th clock cycle 2 bit transactions happen (one at the raising and other at the falling edge of SCLK) . I would like to know if that is correct, because I am not able to program the chip correctly, even though I can read the default register values, but the sample rate does not respond to my commands.

Any help will be very much appreciated.

Att, Felipe.

over 9 years ago

0 Vishy Viswanathan over 9 years ago

TI__Mastermind 21685 points

That figure illustrates how the ADS device internally functions: all input data on the serial data in (SDI) pin is sampled on the rising edge of SCLK and all output data is driven on the falling edge of the serial clock.

Please refer to this app note and source code for how the spi read/write are done with msp430

http://www.ti.com/lit/pdf/snaa211

and the associated software zip file

http://www.ti.com/lit/zip/snac054

Thanks

0 Felipe Schneider over 9 years ago in reply to Vishy Viswanathan

Prodigy 80 points

I did manage to solve the problems trough a different path:

First I set the SPI in one mode only - sampling at the rising edge. From there I never changed the mode again. I then followed the commands listed on the datasheet and only implemented two more, to turn off the conversions and turn off the internal oscillators.

Thank you for your help, I appreciate it.

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ADS1293 SPI protocol