 This week's Eye on MPI is brought to you by DigiKey and it's from TDK. That's right. TDK makes some cool sensors, checking out what the latest new products are from DigiKey and I saw this nice sensor and I thought I would show it off. It is the TDK AVD differential pressure module and what I like about this is I love my sensors but sensors are kind of a pain to use sometimes and tough to mount and tough to interface with and what I liked is this is a really all-in-one ready-to-go like board mountable module that makes it very, very easy if you want to add differential pressure sensing to your product or project and you just don't want to deal with spinning up a board. You want something ready to go with I squared C for really quick integration. So this is the series, the part number is quite long but it's I called the AVD series. So these are differential pressure sensors so what would you want differential pressure sensing for? Well normally we show off non-differential pressure sensors and those are of course good for just of course if you are trying to measure pressure in a cavity, they're good, they're also good for determining altitude and how far you've moved up and down because pressure changes the altitude and you can, if you subtract the C level pressure you can determine how high up you are so they're used for drones and robotics watches that tell you how many steps you've taken, stuff like that. Differential pressure sensors are different, these tend to be used for industrial equipment and in specific a very common example is you have a HVAC system and the HVAC system has a filter, chances are you have an HVAC system and there's a filter in it and the filter keeps dust out of the HVAC so it keeps the HVAC motor from getting clogged with dirt and of course keeps your air clean too, it's a nice filter for your air but the filter gets clogged up with dirt and dust and then the HVAC has to work harder and harder and harder to push air through the filter and you're supposed to like check your filter every six months and you know like yeah sure but one you could forget or second maybe you have a building that's so large that it's hard to check the filters all the time. Well a differential pressure sensor you'd put each prong on one of the sides of the filter and you would notice that the pressure would be much higher on the side that's trying to push the air through the filter and that differential is what is making it difficult for the HVAC system to work. Once it triggers past a certain pressure threshold maybe you would send an SMS or maybe it would you know turn on LED or turn on alarm telling you hey it's time to change the filter so it's the common use for differential pressure sensors sometimes it could also be used for telling how much liquid is in a vat you know by measuring the differential pressure from inside or outside you know enclosed vat but yeah basically that's what it's used for a lot of industrial measurements not necessarily for altitude measurements. So this sensor like I said what's very nice is that it has I squared C data out you basically don't even have a register map you just read four bytes from it and it just spits out the data and just to shift the data around there's a little algorithm that tells you how to multiply it out and title linearize it. There's two connectors so you don't need to solder their JST SH5 pin connectors there's an interrupt telling you when data is ready I didn't use that I just connected up ground power clock and data and wired up 200 we know wrote the code for the algorithm on the right and it just worked it was actually pretty sweet here's the code and I'll show the demo on the overhead but you can see it's very short a lot of it's just shifting a couple things doing a few multiplies and out spits out the temperature and pressure. Since it's differential you'll have to determine like what is the max pressure difference you're going to have in your system this comes in three types oh can you expand it so I can read it because I think it's yeah two ten sorry on the right it says 16 sorry 1.6 kilo Pascal's 10 kilo Pascal's and 700 kilo Pascal's so depending on the pressures you're measuring you'll pick different ranges to get the most accuracy and precision. What I like about this sensor is it's again it's a module especially if you want to like install this in some sort of HVAC filter system and then run the cable for data to someplace else it's also daisy chainable if you want to have multiple sensors you can do that but it's ready to go it's a kind of a fully integrated slim module that's that can be you know it's injection mold and ready to be installed into your whatever measurement system you've got there's also a step 3d model and it's nice it's even got all the coloring for the module and all that and best of all it's in stock so let's show the demo real fast I just put together it was such an it was like so easy took me less than an hour to do this I've just got my little microcontroller set up here let me focus lock okay I got the OLED and this is differential so remember it's not doing the absolute pressure it's doing the pressure difference between the two prongs that's why you see it's zero but if I if I plug up one you'll see it's going to negative pressure and if I plug the other one it goes into positive pressure this is not calibrated I can basically just got the data out and this is what popped out but it was very easy to wire it up I just connected it through I scored C verified the address read the data and then calculated out here's one quick question is it precise enough for a p-tot tube it's 14 bits of data I don't know off top my hand what the pressure differentials offer a p-tot tube because I've never flown before but pilots out there if any of you know popping the chat and say what what the differential pressure is but it's quite good I mean this is this is basically a lot of people use analog differential pressure sensors and you can use them but they're kind of a pain to use and again if you want to integrate this with something like a single board Linux computer like a Raspberry Pi that you can't buy I scored C will just work whereas with analog it's like suddenly you're getting into like okay you have to have an analog front end and you have to do the calculations and there's more wiring this is very plug-and-play like you know no external components required okay and that is this week's eye on MPI