Can this ADuM1410 be used to interface the SPI signals from this Metering IC to this WFI32E01PC module?
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1\$\begingroup\$ May I ask WHY you want to isolate the data lines? We use one of the ADUM series at work for a project where we need to ensure that MOPP2 for >2kV and man does this cause a lot of pain. So you should be 100% sure that you really need that separation. \$\endgroup\$– Christian B.Commented Jul 14, 2023 at 7:19
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\$\begingroup\$ @ChristianB., thank you for sharing your valuable experience with this IC. I am using the 3 phase metering IC and need to share that information to the WFI module. Since, the 3 phase metering IC is with refering to the RYB-Neutral and the WFI32 is with respect to the board digital ground reference, we need some isolator. Hope my approach is correct? \$\endgroup\$– FreshmanCommented Jul 14, 2023 at 8:15
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\$\begingroup\$ We don't know what approach you have to determine if it's correct. It depends where your board digital ground is referenced. \$\endgroup\$– JustmeCommented Jul 14, 2023 at 8:45
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\$\begingroup\$ @Justme, could you explain on what you mean by, " depends where your board digital ground is referenced." \$\endgroup\$– FreshmanCommented Jul 14, 2023 at 8:46
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\$\begingroup\$ How you power your MCU board and if it has user touchable parts or external connectios defines if you need an isolator or can you keep the MCU connected directly to mains referenced measuring IC. But this is getting off-topic, as your question is if you can use a specific isolator. \$\endgroup\$– JustmeCommented Jul 14, 2023 at 8:51
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Electrically you'll be fine. You have to note that this digital isolator limits the data rate to 10 MHz, while SPI can go beyond that.
For SPI you have 3 master-output signals (MOSI, CLK, nCS) and 1 slave-output signal (MISO), so you'll have to use the ADuM1411 part instead.
Source: Datasheet
- Why should this IC be used to interface the metering IC and the module? Why can't the metering IC SPI signals be directly interfaced with the module?
Both the PIC32 and the ATM90 can be powered with 3.3 V. So if both parts are on the same PCB and voltage domain I see no reason to isolate the SPI signals.
- What's the difference between 1410 and 1411 part? It would be better if you could also add some information on the meaning of the ordering table guide on page 22 (like what is the meaning of the number of inputs on one side versus the number of inputs on the other side)
The 4 I/O paths (VA, VB, VC, VD) are uni-directional.
ADuM1410, ADuM1411 and ADuM1412 specify 4, 3 and 2 inputs on the VDD1 side, respectively.
For SPI the slave has 3 inputs, and the master has 1 input. So you have to choose the option with 3/1 inputs, which is the ADuM1411.
I've highlighted the signal directions:
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\$\begingroup\$ Thank you for the answer. Just a couple of small queries. 1. Why should this IC be used to interface the metering IC and the module? Why can't the metering IC SPI signals be directly interfaced with the module? 2. What's the difference between 1410 and 1411 part? It would be better if you could also add some information on the meaning of the ordering table guide on page 22 (like what is the meaning of the number of inputs on one side versus the number of inputs on the other side)? \$\endgroup\$– FreshmanCommented Jul 14, 2023 at 6:54
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1\$\begingroup\$ @Freshman First you asked if this isolator can be used. Now you ask why it can't be connected directly. It might be possible but might be unsafe. We don't know your system what is possible. But that is a completely different question. You might not need an isolator but you can use it. And which part you must use depends on which wires need to be isolated to which direction. Do you understand how SPI bus works? \$\endgroup\$– JustmeCommented Jul 14, 2023 at 8:43
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1\$\begingroup\$ @Freshman What's the difference between 1410 and 1411 part? <-- look at the red arrows. \$\endgroup\$– Andy akaCommented Jul 14, 2023 at 8:44
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\$\begingroup\$ @Justme, I am using the 3 phase metering IC and need to share that information to the WFI module. Since, the 3 phase metering IC is with reference to the RYB-Neutral and the WFI32 reference is with respect to the board digital ground reference, we need some isolator, right? For that I thought we might need some isolator. Or do you suggest I connect the metering SPI output directly to the WFI module? \$\endgroup\$– FreshmanCommented Jul 14, 2023 at 8:45
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2\$\begingroup\$ I am not suggesting anything until there is enough information to answer if the boards can be connected directly or through an isolator, but that was not the point of your question, you simply asked if an isolator can be used, and yes you likely can if you select a correct isolator for SPI bus and can power the mains referenced side and MCU side with isolated supplies. \$\endgroup\$– JustmeCommented Jul 14, 2023 at 8:48