 Hi, on MPI. On MPI, brought to you by Digikey, I think. Digikey, this week it is Renaissance. That's right. What is the MPI? New product introduction of the week this week. OK, so this is a Renaissance sensor conditioning chip, which I actually had on my list for a while, and it's in stock now. So I'm glad to finally be able to feature it. OK, this is the ZSSC 3241. The SSC is sensor signal conditioning. And Z is when I saw all this stuff starts with Z. The rest of the numbers don't know what they mean, but this chip is pretty cool. When I look at the stuff to do for IMPI, there's a lot of like, here's another MOSFET, here's another Bunker-Boost converter, here's another connector. And so I try not to just cover the same types of things. I like it when there's a new unique chip. And this is definitely unique. I've never seen a chip like this specifically designed for interfacing with resistive and resistor bridge sensors without having to kind of DIY it all yourself using op amps and 24-bit ADCs. So this is a chip, and it's got like, every time you look at it, there's like more stuff that you discover, and you're like, that's kind of cool. It's a chip that's designed, again, to read bridge, half bridge, or resistive sensors. I can actually also do, I think, voltage source sensors. And I'll talk about some of those. And like some of the details, like it can do SPI or I squared C or one wire, but it has analog output. It can set up the resistive style or voltage style sensor in any kind of configuration. And there's like dozens and dozens of knobs and adjustments that you can do to make it perfect for connecting to a sensor. And you probably don't need any other analog circuitry. You just plug this in and you get the ADC, the gain, the calibration, the NVM, everything, for the same price as an ADC. So a lot of people, when they start electronics, they'll make the first sensor project after a button is usually a light sensor like this one. This is a CDS cell, a cadmium sulfide cell. And these are, this is a beautiful diagram by Philby. They're made with a material that as more light hits it, the resistance changes. And so you can basically use it as a light sensor. A lot of people are like, oh, this is a temperature sensor, humidity sensor. But when you actually look at how the sensor works, it's not that you're measuring humidity. You're measuring a capacitor that is affected by humidity or in this case, you're not really measuring light. You're measuring resistance that changes with light. And so for these sensors, the CDS cells, they're pretty easy to wire up. And that's why they're good for beginners. It's a really good, first analog input sensing project because you have your LDR, your light dependent resistor, and then you have a fixed 10K resistor. You turn them into a voltage divider and then you read the analog voltage into your micro controller pin, like in Arduino or, you know, Renaissance R8 4M, you know, Wi-Fi Minima, you can also use those, anything with an ADC. And it's really easy because the voltage reading is done just by every micro controller. They don't have resistor readers, they actually only have voltage divider. So it's another layer, you know, not only are you not measuring light, you're measuring resistance that changes with light, you're not even measuring resistance, you're measuring voltage that will change with resistance that will change with light. And CDS cells, the resistance changes a lot. So depending on whether it's dark or light, you're gonna get, you know, three plus forms of magnitude difference from when it's dark, 300 ohms to, sorry, when it's bright, you know, 100 or 200, 300 ohms, all the way down to 600 kilo ohms when it's dim or dark. So there's such a wide range that that resistor divider, you'll get like zero to three volts pretty easily. It's very easy. Even if you have a 8-bit or 10-bit micro controller or ADC, you're gonna be able to read that difference. But other resistor sensors, especially as you become, you know, a more skilled engineer, other resistive sensors are a little tougher to use. This is a PT100. This is a piece of platinum that is calibrated to be 100 ohms or one kilo ohm in room temperature, 25.0 degrees C. And as the temperature changes, the resistance changes. In this case, it has three wires for calibration reasons, but really it's a resistor that only the red, the two red wires are used. Sorry, the only one of the red and one of the white wires are used. So this is, for example, from the datasheet for an RTD from Honeywell. And you'll see, you know, the resistance changes very, very slightly, but it does have a wide range from negative 100 to 600 ohms. And, you know, it'll go down one quarter or up by 20% depending on the temperature. So there is a little bit of variation, but it's not gonna be the three order of magnitude variation of the CVSL. It's gonna be a much smaller amount. And a lot of people use PT 100 or 1000s because they're very good precision. So you can get, you know, 0.1 degree or 0.5 degree precision and accuracy over a wide temperature range, but only if you can read that resistance at the accuracy that you want. If your ADC has 5% error, it doesn't matter how good your sensor is, you're gonna have the error that comes in from temperature variation or from the resistor variation. Another common resistive type cell is the strain gauge. These come with four wires because they're actually usually pre-wired up in a wheat stone bridge. Not gonna cover wheat stone bridge, don't have time to talk about how that works, but it's a way of, it's a slightly better way than just resistor divider way of measuring resistance changes. This is made by micro printing a conducted material that as it gets bent or twisted or torqued or whatever, the resistance changes and it really is a very, very small amount. Like if you thought the PT 100 was a small variation, this is even less. Like to read a strain gauge, you really need a 24-bit ADC. So what this chip does, you know, so like this is, you know, you can't really use a resistor divider. By the time you get to the PT 100 or PT 1000 or the strain gauges, you can't really use a microcontroller ADC if you want to get many reasonable precision because with the light sensor, maybe you just wanna know is it light or dark? Like those are often used for automatically turning on outdoor lights. You just need to know is it dark or light out? They don't care how many luxe, but with temperature and weight, you often need to have very good accuracy. If you're using that temperature sensor in a chemical reaction container, you need to have it be calibrated and perfectly kept at the temperature for as long as you need for the chemical reaction to occur. For the load cell, if you're going to the store and you're buying a pound of meat or veggies, you don't wanna be charged more and you don't wanna get less. It has to be, you know, within 1% or 0.1% accuracy and precision. You want really good quality output. So, you know, what you can often do is, you know, maybe you have a better quality resistor, maybe you have some code that does some calibration, maybe use an op amp, but it can get, you know, very complicated. You end up with a lot of potentiometers that you're tweaking to try to optimize the output to get it to be the same because each strain gauge has slight variations too. PT 100 are usually pre-calibrated for you, but still sometimes there's a little bit of offset to your sensor. This chip, the SCC 34, well, I forgot the last few digits, the ZSSC, what it does is everything you need. It's got the PGA, the programmable gain stage. It's got 24 to 12 to 24 bit ADC and it's got a math section that can do offset calculations for you and we'll go through it. And then the output again can output in three different ways. You can get the output as SPI, I squared C data or analog output, which I think is very interesting. So you can get the value in perform all these mathematical calculations on it and then you pipe the voltage that you want scaled to the A out pan. Okay, so here are some application examples. They show it with a bridge, a Weastome bridge setup. They show again a PT 100 or PT 1000 is very popular or a PTC resistor divider or you've got a strain gauge. They have one wire output, which I think is kind of fascinating. That's very rare to see something that is programmable with one wire, but it does let you use it in setups like some Dallas 18B20s. You wanna have some other kind of sensor with only one wire output. You can set it up with this. You do have to pre-configure it, but at least then you can read the data back out although one wire is a little slow. There's like I said, bazillion knobs. There is for example, ADC. You can go all the way up to 24 bit ADC if you need that precision, but it's going to be much slower. You're only gonna get, it looks like it takes 4.7 milliseconds per conversion. Whereas 12 bit, you're gonna get it be like 40 times faster. So you have a trade-off of ADC resolution and speed. There's also internally a programmable gain stage, very handy, especially for those strain gauges where the changes in resistance are so, so small. You might want to have multiple, both the 1.8 second gain stage and the 300 times first stage, but when you're dealing with something like a light resistor or a positive temperature coefficient resistor, maybe you don't need as much gain. You don't want to blow out your analog digital input, but this saves you all that op-amp configuration. There's also how you, you can configure it. You saw in the application diagram, you can set up as a resistor divider and it will, you can have it set up with what resistor you want. It'll handle the internal resistor for you or you can set up as a bridge. There's also interrupt outputs. You can tell it, hey, I want IRQ based on this threshold change above or below. And they've got examples for all of that. And then I think I don't have it here, but you can have it in continuous, you can set it for continuous readings or you can do one shots. So if you want continuous, that's when you would have like the analog output or you know, use whatever the data's ready, you read it from iSports, your SPI. There's also non-volatile memory built in. So this would be great for where you put your calibration setting. So, you know, each sensor does have slight change. You know, what, when you get a sensor that, oh, this humidity sensor has, you know, 1% or 2% humidity. Why, how can they get that when most humidity sensors are three to 5%? It's just because they're calibrated. It's not like they build them any better that the sensor itself, the way the sensor is built to be natively have some inaccuracies, but you can calibrate them. And non-volatile memory is where you store that calibration. So you calibrate it in the factory, you send it up to the user and each one's gonna have slightly different settings here for voltage offsets, for temperature coefficients. Like there's all these settings that you can use the non-volatile memory for. There's also a diagnostic check command. So it'll tell you like, hey, your sensor is gonna disconnect it or it's sorted. Or, you know, I think I'm putting this much current in, but I'm actually, you know, this much is what's coming out. So you can make sure that, you know, when you're dealing with these simple resistive sensors, it's very easy for them to get disconnected and suddenly like your temperature you think it is is shooting up or shooting down because it's actually measuring an open circuit. And I also recommend there is eval-boards available, particularly because this sensor has so many knobs and settings. What's nice about getting the eval-board is that you plug it into your computer and run the software and you can tweak each one of those settings and see the output. So you don't have to like, wait the whole drive or if you're, what is it gonna, you know, with your particular sensor, what's the configuration values you're gonna need? You set it all up in the eval software and then you can, they have an output that tells you what I squared C or SPI commands were sent. You can then import that into your firmware. And you use this example, showing all the different places you can configure it. And it is in stock. Bill Lunditsky. The SZSSC3241 available. And again, the pricing, it's about the same price as a 24 bit ADC. So instead of just getting an ADC that might work only over I squared C or SPI, get this and you get the ADC and the programmable gain and the configuration and the NVM, internal temperature sensors, continuous mode, forever and ever and ever. And you can use it with like pretty much any kind of resistive sensor. And that's our MPI. Hi, on MPI.