EEVblog #1180 - Component Parametric Search Tutorial

What is parametric searching, how is it useful, and how to best use it.
Dave answers a viewer question and hunts down the best microcontroller for the job, explaining and demonstrating parametric search engines in the process.

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[BerndFelsche]

Dave; a man of many tangents. ;-)

And the cheapest microcontroller is .... obsolete

[UpcycleElectronics]

Now I'm no expert as an electronics hobbyist, but I was the buyer/inventory manager for a small chain of bike shops. I spent ages doing searches like this with wholesale suppliers, but I also managed the networked inventory system for the business. In my experience, the data entry side of ecommerce is always under valued. The quality of labor employed for data entry is marginal at best. Digikey is pretty good, but from what I've priced out so far, in my limited experience, you're paying extra for their proficiency on most parts.
The data entry manager is often forced to shortcut certain aspects of the job to keep up. These are often calculated decisions based on data like the most used metrics. Basically this means that the more obscure search metrics will often get bypassed for time. As someone that is very familiar with such a system, I can say I have seen this trend on digikey, mouser, and arrow. If you search for a lot of metrics directly, including the obscure ones, you will often miss many parts because they lack the full entry metrics in the system. I always try to search with as few parametric search specifics as possible to curb this issue.
That's just my $0.002 adsense.
-Jake

[francoisrevol]

Once you've started filtering you may want to remove the search term under the filter, because sometimes components miss it in the description even if they are in the category. Probably not for uCs but who knows, you may miss the right part because of that.

[flymypg]

I've found great benefit combining inexpensive low-pin-count micros with cheap-as-chips SPI/I2C/SMB GPIO expanders.

[bar]

Dave, I think you can search for UART and SPI interfaces easily, just add them as parameters in the 'Search Within Results' text box (under results number)

[josephcote]

In Ye Olden Dayes we would just pull out the manufacturers' catalogs and peruse for something interesting. Not as easy, but you still always found things you hadn't known about.

[FurEngel]

He wants a MCU with 256KB of Flash, which makes me think that he really wants 32KB for MCU code and 224KB for ASCII stuff. In which case, he SHOULD be looking for a MCU with 32KB and a < 30 cent 1Mbit SPI Flash (i.e. W25X10C).

[zivfriedman]

The DigiKey component search mechanism is not only the best electronics search-site (by far), but I must say one of the most responsive self-explanatory and user-friendly websites I have ever visited
Response times are superb, search is coherent, almost all possible parameters are available for filtering and/or sorting, a HUGE database of items to choose from, it includes both active and deprecated/outdated components (for backward compatibility and datasheets)


Simply amazing
Don't understand what the whole fuss is about? try arrow/mouser sites - both are very popular companies and very important in the indeustry, while their search page is not even close to DK's

[shmuelglick]

Important. You forgot to "X" out the search term "microcontrollers" once you were in the "microcontroller" category. If you do not clear the term, I find that some items will not show. Those that don't have that search term in the item description or title. The search may have helped you find right category but may also prevent you from seeing some results later on. You must clear the search term from the filters before going ahead with the other filters.
Great videos! Keep it up Dave!

[coldfingersub]

Wish I seen this when I took my first electronics class I did not even know what a BOM was 😂. I spent half a year learning and educating myself running down the rabbit hole learning how to use all those features three years later I’m still learning and discovering new things all the time. This video should be mandatory watching for all schools electronics 101 class.

[aron]

Now I have some project improvement ideas. Thank you for the FET with the internal sense.

[luscus]

My major supplier is RS. I LOVE their parametric search.
And on top of that free freight. I live in Geraldton, WA (500 odd km's north of Perth). Toll have my parts here from NSW in 3 days max. Love it.

[Jellow]

addressing the specific case of 25+ I/O with 256k+ prog mem, UART, SPI:
If you really must stick with these requirements I would say your best bet is TIs MSP430 series. You can get them reasonably cheap from China.
E.g. MSP430F5438A: 256KB program size, 87 I/O, up to 4 serial interfaces (UART, SPI, IrDA or I2C) from LCSC in 100 qty is $2.68

However I agree with Dave that the size is most likely overkill and I would encourage rethinking the design.
If you have a lot of static data think about using an external ROM chip instead of bloating your application size with it or evaluate reducing the required I/O by using shift registers.
It's often cheaper to build a multi chip solution than trying to get a single jack-of-all-trades device.
E.g. ATtiny20 (12 I/O, 2k prog mem, SPI + TWI)
+ 2x SN74LS165 (8-bit Serial-out shift registers)
+ 2x SN74LS164 (8-bit Serial-in shift register)
+ AT25256B (256kb EEPROM)
= $1.20 - $2.00 total (depending on packages, suppliers and quantity)

[redsquirrelftw]

When I'm really bored at work I sometimes do searches for random stuff. I must really be a nerd. Most people just go on Youtube. My monitor faces the entrance though so I don't have that luxery as it's the first screen people see when they come in our area. At least parametric searching sorta looks work related even though my job is not electronics. :P

[kmonyt]

I know you mention this half way through the video, but clicking that "in-stock" button on digi-key is the single most important one. This eliminates old parts, obsolete, long lead times(normal lead time for out stock is in MONTHS). Make sure to che ck it!

[GttoLivefree]

The power of the 'Normally Stocking' button = you will not miss the high runners that are sold out at the moment. The 'In Stock' button would be better named 'In Stock Today'.

I always use the 'Normally Stocking' button when filling out my BOM- hate to miss the popular selling parts that might be on their way back on the shelves!

[niw]

Octopart is great as well, especially when you pick the part and ready to shop. You can check lots of suppliers’ inventory including prices with breakpoints.

[MaxWattage]

Hi Dave,
The major issueI have with distributors and parametric searching is that they never specify the silicon revision of the die inside the chips you are buying.
Chips all come with errata sheets, which list what bugs are present in which revision of the silicon.
However, when I buy through distribution it is pot-luck as to what revision of the silicon I will get in the chips, and you can't tell from reading the packaging labels either.
Often you have to solder the part to a PCB and then read-back a specific register before you can find out the revision number. (e.g. Microchip microcontrollers are like this)
That's a nightmare for manufacturing. You have to waste a PCB for every batch of every chip you order, just to test whether the chips are good or contain hardware bugs that totally break your product.

[kjur]

Idea for next one, take some board with chips that have scraped off numbers and try to find it by pinout, package etc.

[PlasmaHH]

Lot of websites have huge problems with parametric searches. For some components values are missing, and for a lot of websites the "values" are just strings, so if you are interested in a range of values you not only have to select a range of values, but also have to go through all of the possible ways to write it (0.01µ vs. 10n) and then the site throws at you an error that you only can have 300 filter values. It is really one of the most annoying things out there.