Stellaris gone. What would you recommend for a USB prototype? - Page 1
Forum section: electronics / general

author: drudru
author_rank: Newbie
timestamp: October 25, 2013, 07:34:43 pm
content: Hey,A couple of days ago, I was just thinking of using the TI Stellaris eval board I got last year. I then went to TI's site and discovered no mention of it. A quick google search led me to this forum.A post here was really informative concerning the disappearance of the Stellaris line from the TI product lineup.Also mentioned in the thread were the issues with the product in general. I'm not sure what I'll do with these devices now. At the time they looked great as a low-cost ARM platform, so I need to make a more careful decision.Given the knowledge of some of the people on this board, I thought maybe it would be a good place to get the real-world view on similar systems.Here are my thoughts:I want to prototype a low-bandwidth USB device. It would be a nice option to do Block storage, Serial Port, and HID too. I'll have to get a driver written for the various OSs for the new endpoint.Another big nice to have would be the ability to have a debugger link to the device while developing the new USB endpoint. So I guess the device should support multiple endpoints at the same time.SDHC storage and I2C for display are required.32 bits and a minimal unix like OS would be nice. With an OS like that, I could just upload a new userland executable to test new USB code.I'm currently looking for something like the Fubarino. It basically has everything I need.I'm also considering the Teensy 3 as I believe it can satisfy things as well.The pros for the Fubarino are: it has everything i need for the prototype. It has a real OS (retrobsd) with mmu.The ???s for the Fubarino are: USB flexibility, and community support, issue with specific chipThe pros for the Teensy are: ARM based, great project owner, great communityThe ???s for the Teensy are: unknown USB flexibility, issue with specific chipWhat do the gurus here think?Thanks, Dru

author: grego
author_rank: Frequent Contributor
timestamp: October 25, 2013, 07:46:23 pm
content: Stellaris isn't gone - they just renamed it to Tiva. It's the same thing. For example you now have the Tiva Launchpad instead of the Stellaris Launchpad.They made some enhancements to the chips (Tiva equivalent to the LX4F120H5QRF now has additional functions on board but code for the LX4F120 compiles just fine on the LM4C123 without changing anything). Other than that, identical. You don't even have to change libraries if you don't want to (although I'd recommend it just to be up to date).

author: drudru
author_rank: Newbie
timestamp: October 25, 2013, 09:24:46 pm
content: Thanks. The other thread mentioned a lot of errata with the chips and the chips are no longer available. Several engineers questioned whether the line would even be available (Tiva-C) in the future.

author: Dongulus
author_rank: Regular Contributor
timestamp: October 25, 2013, 09:25:24 pm
content: The user guides for the Stellaris Launchpad can still be found on the web.TheUSB User Guidehas all the APIs you'll need for the USB.ThePeripheral User Guidehas APIs for I2C other good stuff.You might want to get a SDHC breakout board so your uC can read and write through SPI or I2C instead of dealing with more complicated control signals.

author: dannyf
author_rank: Super Contributor
timestamp: October 26, 2013, 10:32:31 pm
content: QuoteThere are quite a few versions of the chip and their bugs for the various versions are well documented. I haven't personally run into any of them in late production run chips but did have to deal with adc-related issues in one of the earliest 4F120s.Every chip has bugs. Some OEMs do a better job than others in documenting those bugs and I wouldn't stop using a chip because of the number of errata published, especially if those bugs have no bearing on what you are trying to do.BTW, those are great little chips.

author: rsjsouza
author_rank: Super Contributor
timestamp: October 28, 2013, 12:03:29 am
content: QuoteI think that was part of the reason (or the single reason, I don't know) why they put as NRND* the Cortex M3 Stellaris product line entirely. Tiva is Cortex M4 and is surely a new silicon spin.*NRND is different than obsolete/discontinued. It usually means there is no roadmap of future products and no free samples, no new development boards, etc, etc, etc. but the device is still in production.

author: grego
author_rank: Frequent Contributor
timestamp: October 28, 2013, 01:27:00 am
content: Stellaris was also Cortex-M4 (LM4F120 for example, and the F232).NRND is just "Not Recommended for New Designs" - e.g. they are phasing out production (or never going into full production) with a chip -- you can still get it when its NRND but they are making no guarantee for how long supplies will be available. In effect it's like an EOS notice from an equipment manufacturer. Not quite EOL yet, but getting there.

author: rsjsouza
author_rank: Super Contributor
timestamp: October 28, 2013, 02:42:01 am
content: Quote from: grego on October 28, 2013, 01:27:00 amI did not say otherwise; the Cortex M3 Stellaris is NRND, but I did not reference Cortex M4 Stellaris, which seems to have been simply vanished from TI's website and replaced by the Tiva brand.Quote from: grego on October 28, 2013, 01:27:00 amNRND does not mean the production is being phased out - you can still buy it in volume for a long time (e.g. a C32 DSP is in NRND for almost 10 years AFAIR). In fact what it means is the support for new designs is de-emphasized in favor of other devices. Besides, I don't think the semi manufacturers have a timeline that guarantees availability for any product - it is a matter of how interesting it is to still manufacture it (other reasons such as floods/earthquakes/plant closeouts/etc may push a product into obsolescence as well)Lifetime buy is when the manufacturer puts a timeline to supply the final production run...I got bit by that in the past, thus I had to read the fine print. A lot of this is mentionedhere.

author: Maturola
author_rank: Contributor
timestamp: October 30, 2013, 07:08:52 pm
content: Quote from: drudru on October 25, 2013, 07:34:43 pmMay want to take a quick look at the ST STM32 line, they got some pretty good stuff and pretty solid line used on many products and markets

author: Bored@Work
author_rank: Super Contributor
timestamp: October 30, 2013, 09:46:22 pm
content: Quote from: rsjsouza on October 28, 2013, 02:42:01 amTI claims NRND is a marketing status "only". Well, it is supposed to affect customer decisions and does so in ways TI might actually not like. E.g. triggering that a customer not only considers other Ti devices, but other manufacturers.QuoteWell, there is kind of a standardized timeline when a product is discontinued. Semiconductor manufacturers typically follow JESD48B. JESD48B says you should notify customers. And from that notification onwards customers should be able to order a device for at least six more month. And customers should get a shipment over a period of at least 12 month from the notification. These are minimum time periods.The devil is of course in the details. You need to have a contract that guarantees you notifications according to JESD48B. And even then you need to have bought devices recently within a certain timeframe. I.e., you basically need to be a recurring customer.

author: rsjsouza
author_rank: Super Contributor
timestamp: October 31, 2013, 12:00:34 pm
content: Quote from: Bored@Work on October 30, 2013, 09:46:22 pmYep, I agree with you; as the name implies, this change in status (no matter how it is marketed) is intended to make people consider other devices if the design is new.Quote from: Bored@Work on October 30, 2013, 09:46:22 pmQuote from: rsjsouza on October 28, 2013, 02:42:01 amQuote from: Bored@Work on October 30, 2013, 09:46:22 pmThe thing is most people buy from distributors, therefore it becomes a matter if they are organized enough to have your information on record and let you know about that. In my experience I did not have any problems with that (I was informed two or three times a device or board was being put in NRND, one of them was Stellaris), although I do mostly small purchases.