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Small but mighty eMMC flash storage grows its enterprise role

Many common devices, like your cell phone and tablet, use eMMC flash for storage. But the internet of things will soon make eMMC a major part of nearly every enterprise.

As the internet of things ramps up, we need to give some thought to all of the data created by those "things" and how eMMC flash storage can help.

For example, smart refrigerators track food expiration, re-ordering, calorie counting and more, which amounts to quite a lot of data over a year. But what purpose does all of that data serve?

The re-order and other automated functions all need apps, and it's a good bet they won't talk to each other. One way historical buying data can be imported into a new app is by changing from one supermarket to another. The only realistic way to do this is via storage in the refrigerator. Anything else requires nonexistent standards or sharing apps, and we'll probably change the refrigerator before that happens.

This puts the onus on the "thing" to store its own history. It doesn't need to be perpetual, but it has to be long enough storage to meet all but the most extreme needs. The answer is to add flash to the internet of things (IoT) device, and this means an embedded MultiMediaCard (eMMC).

What is eMMC?

EMMC is a parallel-interfaced simple storage device consisting of a controller and a chunk of NAND flash, all packaged in a tiny ball grid array chip. This type of memory currently holds 128 GB of data, and we can expect the new standard extension (version 5.1) to trigger capacity increases into the terabyte range within a year or two.

Image of an eMMC chip

Think of eMMC flash storage as the smallest storage drive in existence. It is ideal for jobs that need a chunk of nonremovable memory in a tiny footprint, which is why it is ubiquitous in cameras and smartphones as the base memory module. The larger modules serve that purpose in computer tablets. It's fair to say that the smartphone and tablet would not have been anywhere close to the level of success they've achieved without this tiny chip.

Small doesn't mean puny, though. The latest specification for eMMC flash storage calls for transfer rates in the 400 MB per second range or better, which is right up there with many solid-state drive specifications. That data rate is what makes playing a movie on a tablet or phone so smooth.


For many applications, this speed results in a reduction in the dynamic RAM (DRAM) or static RAM needed to perform the workload on the unit. While eMMC flash storage is not fast enough to replace either type of primary memory, it can act as a paging store that creates a much larger virtual memory. This is important in small portable devices where the power used to intermittently read or write data is much lower than the power needed for an equivalent amount of DRAM.

Cost, security and ease of use

One might ask why embedded memory is useful when a memory chip such as an SD card is available. The answer is mainly cost, since eMMC beats the memory slot mechanism and the cost of an SD card by a decent amount in a very cost-conscious market. Complicating things, however, is the need to preload OSes and apps and to keep the OS away from removable media. If you unplugged the only memory in a tablet, you'd own a brick.

Going back to IoT, we are looking at smart sensors and control devices that cover everything from surveillance to medical testing. All of these, like the tablet, need an OS and app software, and so cost, security and ease of use all suggest that a fixed memory device is better than one that can easily be swapped out.

Issues seen in computer servers, such as write cycle wear, are not serious considerations in the sensor space, since most applications have low rates of data creation, while thermal specifications are high enough that use in ruggedized gear for transportation or military use is no problem.

Ultimately, eMMC flash storage is not the highest profile storage solution around, but it is pretty ubiquitous. The very existence of the mobile revolution and IoT owes much to this tiny workhorse.

Next Steps

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