How to search for components DigiKey/RS - Page 1
Forum section: electronics / beginners

author: Nogtail
author_rank: Regular Contributor
timestamp: September 23, 2016, 06:27:13 am
content: I'm trying to find the cheapest microcontroller with inbuilt USB but haven't had much luck working the search on DigiKey or RS.On RS if I filter by "USB channels: 1" I get a heap of micros that don't have any mention of USB in their datasheet (PIC10F, PIC12F...)On DigiKey if I select USB under Connectivity I only get a few results, do I have to select every combination that includes USB?What am I doing wrong?

author: Simon
author_rank: Unknown
timestamp: September 23, 2016, 06:30:20 am
content: Any database is only as good as the quality of data you put in. If RS have not filled in the information correctly for the types of uC you are looking for you will find nothing. Both RS and farnell are disastrous in their search functions. Every time i try to use RS and their parametric search the page just keeps reloading with no search. Farnell are notorious for having incorrect or limited information but their search works. If on digikey you only find a few results chances are those are the only ones

author: kripton2035
author_rank: Super Contributor
timestamp: September 23, 2016, 06:34:13 am
content: https://octopart.com/search?q=pic18%20%20usb&sort=avg_price&sort-dir=asc

author: Nogtail
author_rank: Regular Contributor
timestamp: September 23, 2016, 06:48:33 am
content: Quote from: Simon on September 23, 2016, 06:30:20 amThere are plenty of micros on DigiKey with USB that don't show up when I just search for USB because they have other connectivity options, e.g. the PIC16F1454 doesn't show up because it has I²C, LIN, SPI, UART/USART as well as USB. If I were to search for every connectivity combination that includes USB I would be there for hours though, as there seems to be over 350 combinations that include USB. Is there a better way?

author: Simon
author_rank: Unknown
timestamp: September 23, 2016, 06:53:34 am
content: good god, they look pretty shit, put in "mosfet" and look at what the "parametric" options are, most of them nothing to do with a humble mosfet.

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: September 23, 2016, 07:34:03 am
content: Quote from: Nogtail on September 23, 2016, 06:27:13 amYou're expecting RS's search to be useful. It rarely is. I wouldn't think of using it to look for something that detailed.Digikey has by far the best parametric data, and would always be my first choice for searching, even if I wasn't going to buy from them, however for more specialist stuff like USB you're just going to have to do a rough para search to narrow the options down and then dig through datasheets for anything that looks promising.IME search quality is generally in this order of decreasing usefulness :Digikey<huge gap>MouserFarnellRS

author: tszaboo
author_rank: Super Contributor
timestamp: September 23, 2016, 08:55:47 am
content: The issue is, you are not using it right. Why would you search for the cheapest MCU with usb? If it is a Renesas, would you buy that? If it is a xilinx SOC, with software that cost thousands, would you buy that? You decide on the manufacturer, or half a dozen manufacturer, where you have tools, knowledge, and search the website of those. Or you ask your (not warehouse) supplier, who is not Digikey.

author: wraper
author_rank: Unknown
timestamp: September 23, 2016, 09:37:30 am
content: Quote from: NANDBlog on September 23, 2016, 08:55:47 amSearching manufacturer's website is nearly useless for cost optimizing or searching for readily available parts.

author: Tandy
author_rank: Frequent Contributor
timestamp: September 23, 2016, 09:40:54 am
content: Quote from: NANDBlog on September 23, 2016, 08:55:47 amI don't think there is anything wrong with wanting to search for micros with USB ordered by price. It doesn't mean that you necessarily buy the cheapest one but makes it possible to find what parts are available in the price range you want.

author: Psi
author_rank: Super Contributor
timestamp: September 23, 2016, 09:43:18 am
content: think carefully if you really do need a USB micro and if you want to deal with USB yourself.Might be faster/easier/cheaper to use a ebay/aliexpress USB to serial module.Also, unless you want to build 1000 of something, you might not want to pick the cheapest POS usb micro. It may turn out to be full of silicon bugs and annoying to program and debug.

author: MK14
author_rank: Super Contributor
timestamp: September 23, 2016, 10:40:11 am
content: Quote from: Nogtail on September 23, 2016, 06:48:33 amNo, you can do it, I frequently do that same search "USB" on Digi-Key, as I want to see what ones are available, but insist on USB.I think you selected the "USB" option in the parametric search. Unfortunately, that does NOT work out too well. As I think you just found out.The way to do it on the Digi-Key web site, seems to be, that you choose the basic MCU you want. I.e. you may have hundreds or thousands, showing up in the search results. Then within the "Search Within Results" box, towards the top. Put in "USB". It should now say (after clicking), "Search Entry: usb [x ] ", and restrict itself to ALL Mcus, with USB capability.Here is one I did for you, as an example:http://www.digikey.co.uk/product-search/en/integrated-circuits-ics/embedded-microcontrollers/2556109?k=usb&pkeyword=&FV=fff40027%2Cfff800cd&mnonly=0&newproducts=0&ColumnSort=0&page=1&quantity=0&ptm=0&fid=0&pageSize=25You can add multiple search parameters that way. E.g. If you must have at least one SPI port, you can add that in the same way. You can have as many terms as you like, as far as I can tell.The parameter search DOES work, but you have to click/highlight EVERY USB entry and there might be fifty or hundreds, so that is NOT a good way of doing it. I think you ONLY clicked on one of the parameter USB lines, all 50..100++, would have been needed. Hence why the refine search method is easier/best, apparently.

author: Ian.M
author_rank: Super Contributor
timestamp: September 23, 2016, 11:10:20 am
content: Microchip cant even get this right for their own parametric search tool, and as the product selectors allow you to dump sections of their product database to a downloadable CSV file, if you are familiar with their product range, you can easily see that its not just the tool thats borked, but the underlying data has many errors.By the time the likes of RS have imported manufacturer's product data, a process they probably out-sourced to 3rd world minimum wage data wranglers, you are lucky if the specifications don't tell you the MCU is powered by an integrated 'Mr Fusion' or Vdd is specced as 6.3V AC filament supply! Add a product selector interface built by a fresh out of college web developer who's never picked up a soldering iron in anger and probably wasn't allowed Lego or Meccano because his mummy thought he'd choke himself eating it, and you get a U.I the captain of 'Ark B' would find frustratingly inadequate.That's why you skim all the new product briefs for MCUs you have or can afford the toolchain for, and keep your own notes of who's got what in the way of interesting parts - at least enough to Google for them. If you are building less than 10K units, you'll probably never recoup the savings from using the absolute cheapest, due to the costs of getting up and running with some obscure toolchain, and finding the documentation doesn't even make sense in Chinese! If you are building more than that per annum, you've got the resources to throw a couple of Chinese speaking bilingual interns at refining your shortlist .Just give me a parametric tool that allows me to select ranges by minimum and maximum numeric value, *DOESN'T* use a simple alphanumeric text sort to order the list, doesn't cram multiple numeric values in a free text field, knows 5V is the same as 5.0V and 5000mV, and preferably lets me free text search within each parameter list for a group to include or exclude in bulk. Ideally, let me add a search to my existing result set as an OR, and save searches and result sets as packed URLs that aren't session dependent so I can share them with colleagues. I doubt I'll ever see it this side of the pearly gates, and even then its only likely if St Peter recruits the old-skool analog IC designers to ride herd on the web developers (if he even let the web developers in in the first place)!

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: September 23, 2016, 11:32:20 am
content: Quote from: Psi on September 23, 2016, 09:43:18 amThis is something where the quality of manufacturers' libraries,examples etc may be more important than price

author: tszaboo
author_rank: Super Contributor
timestamp: September 23, 2016, 11:45:11 am
content: Quote from: wraper on September 23, 2016, 09:37:30 amThis must be the most useful useless website ever.And you have manufacturing life cycle, 1K pricing, all the information you need to make an educated choice. Saying that it cost 2.5 USD on digikey is NOT a good measure, as I can guarantee that you are not going to pay that much for it.Browsing Digikey for microcontrollers. That just blows my mind. I do that for resistors or special ASICs that I did not even know existed.

author: tggzzz
author_rank: Super Contributor
timestamp: September 23, 2016, 02:15:52 pm
content: For a completely different search engine, try parts.io.It might be helpful, but the problemis"difficult", for the reasons others have mentioned.