{"id":16245,"date":"2016-08-19T10:00:23","date_gmt":"2016-08-19T17:00:23","guid":{"rendered":"https:\/\/blog.digilentinc.com\/?p=16245"},"modified":"2021-06-16T13:57:25","modified_gmt":"2021-06-16T20:57:25","slug":"introducing-the-pmoddpg1-differential-pressure-gauge","status":"publish","type":"post","link":"https:\/\/digilent.com\/blog\/introducing-the-pmoddpg1-differential-pressure-gauge\/","title":{"rendered":"Introducing the PmodDPG1 – Differential Pressure Gauge"},"content":{"rendered":"
\"DPG1
PmodDPG1 Differential Pressure Gauge<\/figcaption><\/figure>\n

Differential pressure sensors are often used in industrial applications, but they are also great for a\u00a0number of personal projects. That\u2019s why we\u2019ve added the PmodDPG1<\/a> differential pressure gauge to the Pmod<\/a> sensor family!<\/p>\n

The PmodDPG1 is a differential pressure sensor designed for use with dry fluids such as air. It uses NXP\u2019s MP3V5010DP<\/a>\u00a0monolithic piezoresistive transducer to sense changes in pressure between two ports. The MP3V5010DP outputs an analog signal proportional to the applied pressure that is accurate within a 5.0% maximum error over 0\u00b0 to 85\u00b0 C. The onboard 12-bit ADC then digitizes the signal, maintaining the accuracy of the sensor and allowing for use with a simple SPI<\/a> interface. Obtaining\u00a0useful pressure data is then a quick and easy conversion using the equation below.<\/p>\n

P (kPa) = (measured ADC value\/4096 \u2013 0.08)\/0.09<\/p><\/blockquote>\n

What is differential pressure?<\/strong><\/p>\n

Differential pressure<\/strong> is simply the difference between two applied pressures. This is opposed to gauge pressure<\/strong> which is always measured with reference to atmospheric pressure. For example, if one port of the PmodDPG1<\/a> was measuring an applied pressure while the other port was open to the atmosphere, the resulting measurement would actually represent gauge pressure, or absolute pressure<\/strong>\u00a0(which is always measured with reference to a vacuum). Therefore, if both ports on the sensor are exposed to atmospheric pressure, the PmodDPG1 should output a measurement very close to zero. The graphic below from a National Instruments whitepaper on pressure measurement gives a good visualization of the three types of pressure.<\/p>\n

\"pressure
Graphic showing three types of pressure. On the left, REF is a vacuum while in the center REF is atmospheric pressure and on the right REF is an applied pressure.<\/figcaption><\/figure>\n

What is a monolithic piezoresistive transducer?<\/strong><\/p>\n

A transducer is simply a device that converts changes in physical quantity to an electrical signal that we can analyze, or vice versa. In the case of a piezoresistive transducer, this conversion happens when the material in the device is mechanically deformed, causing a change in electrical resistivity. This is known as the piezoresistive effect and is leveraged in a range of conventional resistive pressure measurement devices such as strain gauges. Putting monolithic or monocrystalline in front of these two terms technically just means that it is a piece of silicon cut from a single crystal, but what is important to know is that monocrystalline silicon pressure sensors have a higher sensitivity than most other types of pressure sensors and consequently have come into wide use in more recent years.<\/p>\n

Now that we have these fancy definitions under our belts, how do we actually use the PmodDPG1?<\/p>\n

Applications<\/strong><\/p>\n

The PmodDPG1<\/a> is designed to measure a differential pressure range between 0 kPa and 10 kPa. Therefore\u00a0it is ideally suited for applications such as measuring changes in pressure through a Venturi tube<\/a>, designing a pressure plate to detect when something touches it. This is much like what is used to trigger a\u00a0prop spider to drop when trick or treaters have stepped on your\u00a0porch during Halloween. It can also be used to\u00a0determine pressure exerted by the human lung.<\/p>\n

However, all of these applications require measuring applied pressure at two different points that are likely farther apart than a few millimeters. For this reason, the PmodDPG1 ships with a 61 cm polyvinyl tube that fits snugly over either port on the sensor.<\/p>\n

It is important to note that the PmodDPG1 should not be used to measure bike or car tire pressure, since\u00a0both of these applications require a differential measurement of over 200 kPa.<\/p>\n

\"DPG1
The PmodDPG1 ships with a 61 cm x 2.5 mm x 4 mm (length, inner diameter, outer diameter) polyvinyl tube.<\/figcaption><\/figure>\n

Getting Started<\/strong><\/p>\n

To use the PmodDPG1<\/a>, the raw data from the sensor needs to be converted to a useful measurement. To get users started quickly, we\u2019ve written an MPIDE<\/a> library and example code that converts the raw data to several different units of pressure such as psi and mmHG. See the PmodDPG1 Digilent\u00a0wiki page<\/a>\u00a0to download.<\/p>\n

If using the PmodDPG1 with a Digilent FPGA board, see our wiki page titled Using Pmod IP’s<\/a>\u00a0for instructions on how to get up and running smoothly with MicroBlaze<\/a> designs.<\/p>\n

Questions or comments? Use the comment section below or visit the Digilent Forum!<\/a><\/p>\n

Sources:<\/p>\n

Demystifying Piezoresistive Pressure Sensors<\/a><\/p>\n

Pressure Measurement Overview<\/a><\/p>\n

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Meet our new PmodDPG1 and brush up on some pressure measurement concepts to start adding these awesome capabilities to your projects!<\/p>\n","protected":false},"author":26,"featured_media":16253,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[38,1554],"tags":[],"ppma_author":[4491],"class_list":["post-16245","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-expansion-modules","category-news"],"jetpack_featured_media_url":"https:\/\/digilent.com\/blog\/wp-content\/uploads\/2016\/08\/DPG1-with-board-4.png","authors":[{"term_id":4491,"user_id":26,"is_guest":0,"slug":"talesab","display_name":"Talesa Bleything","avatar_url":"https:\/\/secure.gravatar.com\/avatar\/7445e0f9a1a578bd8aca1528d6ed4c8a?s=96&d=mm&r=g","author_category":"","user_url":"","last_name":"Bleything","last_name_2":"","first_name":"Talesa","first_name_2":"","job_title":"","description":""}],"post_mailing_queue_ids":[],"_links":{"self":[{"href":"https:\/\/digilent.com\/blog\/wp-json\/wp\/v2\/posts\/16245","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/digilent.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/digilent.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/digilent.com\/blog\/wp-json\/wp\/v2\/users\/26"}],"replies":[{"embeddable":true,"href":"https:\/\/digilent.com\/blog\/wp-json\/wp\/v2\/comments?post=16245"}],"version-history":[{"count":0,"href":"https:\/\/digilent.com\/blog\/wp-json\/wp\/v2\/posts\/16245\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/digilent.com\/blog\/wp-json\/wp\/v2\/media\/16253"}],"wp:attachment":[{"href":"https:\/\/digilent.com\/blog\/wp-json\/wp\/v2\/media?parent=16245"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/digilent.com\/blog\/wp-json\/wp\/v2\/categories?post=16245"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/digilent.com\/blog\/wp-json\/wp\/v2\/tags?post=16245"},{"taxonomy":"author","embeddable":true,"href":"https:\/\/digilent.com\/blog\/wp-json\/wp\/v2\/ppma_author?post=16245"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}