I’m using a ADC with SPI output for my application, and I need to have two different devices to receive the data from ADC ‘simultaneously’. Since it is ADC, SPI communication will be single-directional. (Data from the other sides are out of interest.) And I have hard time to find a good example for this. Is this possible? If so, is there any good example? Or do I need any extra devices to duplicate signal properly? Need help..

  • 2
    \$\begingroup\$ I'm assuming that it's an external ADC chip. Are you sure that it's SPI master? All the external ADC chips I've seen so far were slave devices. What is the ADC device / part number? \$\endgroup\$
    – Tagli
    Feb 15, 2021 at 12:20
  • \$\begingroup\$ Audio codec often can be dual role, depending on pin strapping/configuration. From SPI to I2S there's only one toggling line of difference \$\endgroup\$ Feb 15, 2021 at 12:21
  • \$\begingroup\$ @Tagli Oh, then please disregard the mention about master. It will be a regular external ADC from Ti, thought I did not fix the model yet. \$\endgroup\$ Feb 15, 2021 at 12:23
  • \$\begingroup\$ How much do you understand about SPI? \$\endgroup\$
    – user253751
    Feb 15, 2021 at 13:00
  • 2
    \$\begingroup\$ Hint: One of your two "devices" will be configured as a master, and it will interact with the ADC just as if the other "device" did not exist. It ought to be possible to configure your other "device" as a slave. I'm not going to tell you how I think the chip select, clock, and MOSI of the second device should be connected because I'm not a EE, and I can't promise I'd get it right. But imagine if the second device was able to spy on the data that the ADC sends back to the master.... \$\endgroup\$ Feb 15, 2021 at 13:30

2 Answers 2


I have hard time to find a good example for this. Is this possible? If so, is there any good example?

I don't see that it should be any more complicated than this: -

enter image description here

The slave reader would use the SCLK generated and use MOSI for its data input. It doesn't matter at all that the data may be arriving from the ADC rather than from the actual SPI master.


It depends on you clock speed. Theorically you could just split the line and it will work. At higher speed a buffer on each branch would output a better signal (due to many reasons). This is of course valid for both MOSI and SCLK

  • 1
    \$\begingroup\$ Thank you for your time Lorenzo. You mean regular voltage follower with Op-amp by buffer, right? \$\endgroup\$ Feb 15, 2021 at 12:27
  • \$\begingroup\$ nono, that would be slow. A digital buffer like the 74LVC2G241 for 3.3V, for example; it also has great output current which can help with long traces (it can actually drive cables without issues) \$\endgroup\$ Feb 15, 2021 at 12:33
  • \$\begingroup\$ I appreciate your kind advise :) will start from your comment! \$\endgroup\$ Feb 15, 2021 at 12:53

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.