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Can/should a tiva mcu be used inside a car?

Lacho Tomov
Intellectual 980 points

Hello,

I have a small prototype audio device that I'd like to put in my car. It's currently using a tiva mcu.

However I'm wondering if tiva is a good choice for such a purpose - a car device? I suppose it will work, but is it advisable?

I see there's the Hercules family which is specially made for automotive devices - should I port it to hercules?

What would be the benefits of such a port?

Thanks in advance!

  • 0
    Guru 20670 points

    Well, i would, personally,  not consider a audio device in need of MCU like Hercules. Hercules is for Real time. For ABS systems and such, not audio. A ARM-M4 should be better for that.

    It isn't a critical system, doesn't need a real time MCU.

  • 0 in reply to Luis Afonso
    Guru 47900 points

    As a past supplier of MCU products which were automotive & marine in nature - it's the temperature followed by shock/vibration extremes - which (most usually) raise concern. 

    Clearly the greatest temperature range occurs, "under the hood" yet even the passenger compartment can become extremely hot (although never to the degree of "under-hood") and very cold.  (when the car is parked)  Your post does not clarify just where your "audio device" is located.  We'd expect that the control & low-level signals are w/in the passenger compartment - the amplifier may be located w/in the trunk, under hood, or w/in that passenger compartment.

    Depending upon your location - you can judge the expected temperatures when the engine's off.  In Los Angeles - years back - we measured, "top of the dashboard" temperatures beyond 160° F.  (our auto gauges had to perform & survive in that environment)

    We note that certain of the TM4C123 brigade exist in "extended temperature" flavor.  While these do not meet "under the hood" specs - they (may) prove proper for passenger compartment deployment.

    As yours is an audio app. - your power stage will add heat - and that impacts your upper temperature ratings & survival...

    Beyond my anecdotal report here - "horse's mouth" publications from SAE (Society of Automotive Engineers) and SEMA (Specialty Equipment Manufacturers' Association) provide detailed guidelines.  (beware SAE publications (usually) are not free - you'll have to find/negotiate w/friendly subscriber (i.e. proper firm (such as ours) or well equipped library or...) to view...)

    Building and selling w/in this vehicular sector proves to be a, "Double edged sword" - good in that you "escape" many of the home/office regulatory hurdles - bad in the environmental demands.  (not too much in life {anymore} is simple, or straightforward...)

  • 0 in reply to cb1
    Intellectual 980 points

    Thank you both for the replies!

    I was also worried about the temperature ratings. I guess the device will go behind the radio - that should probably be closer to the passenger temperatures, rather than "under the hood"?

    So the tivas are rated for -40 to 85C and -40 to 105C (not sure why there are 2 ratings). And the Hercules is rated for -40 to 125C.

    160F is about 70C, so that should fit into the tiva range... I also expect in my area temperatures to not be much different...

    So I guess I'll stick with the tiva, at least for now, and will probably put some temperature sensor to see what ranges it receives there.

    Thanks!

  • 0 in reply to Lacho Tomov
    Guru 47900 points

    Lacho Tomov said:
    not sure why there are 2 ratings

    It's not unusual to have even more ratings - depending upon vendor's targeted market.  Parts may be built on separate lines or test/verified then binned to be so categorized.

    If your power stage is integral w/the MCU (nearby) I'd choose an MCU w/the 105°C rating - for safety and extended life.  (as MCU will be visited by power stage's heat dissipation...)  (Not to ask - How I (unfortunately) know...)

  • 0 in reply to cb1
    Intellectual 980 points

    Oh ok thanks, so I'll look for that rating.

  • 0 in reply to cb1
    Guru 11940 points

    If your power stage is integral w/the MCU (nearby) I'd choose an MCU w/the 105°C rating - for safety and extended life.  (as MCU will be visited by power stage's heat dissipation...)  (Not to ask - How I (unfortunately) know...)

    Several autmakers require for their electronics the 125°C rating, which often drastically limits the number of possibilities ...

  • 0 in reply to f. m.
    Intellectual 980 points

    f. m. said:

    Several autmakers require for their electronics the 125°C rating, which often drastically limits the number of possibilities ...

    Hmm is that also valid for aftermarket devices that will be used in that car, or it's just for the stock electronics?

  • 0 in reply to Lacho Tomov
    Guru 47900 points

    Our firm past sold primarily to auto & marine aftermarket - where certain requirements (may) be relaxed - provided you make that fact well (and properly) known.  (Hello Mr. Lawyer)

    You may gain further insight by consulting, AEC-Q200 which covers many/most of the automotive electrical qualification issues & definitions.

    If w/in US - that SEMA reference I earlier provided - may prove useful.  The auto/marine aftermarket has a vast spread of capability & legal conformance - strongly advise "against" your making a, "product conformance decision" based upon the efforts, publications of any one vendor - or even a small group - guessing and/or "shortcuts" may prove costly...

  • 0 in reply to Lacho Tomov
    Guru 11940 points

    Hmm is that also valid for aftermarket devices that will be used in that car, or it's just for the stock electronics?

    I have heard about this only for stock electronics.

    However, I'm not in the car electronics business, nor am I a lawyer ...

  • 0 in reply to f. m.
    Guru 47900 points

    f. m. said:
    heard about this only for stock electronics.

    W/in the U.S. - anyone may sue anyone for anything!  (how delightful)

    Thus - is it not legally safest to design your aftermarket product so that it is in close conformance with "industry standards?"  Choice is yours - and every situation is different - you've wandered outside the "safe area" (i.e. tech) of this tech forum...

  • 0 in reply to cb1
    Guru 11940 points

    W/in the U.S. - anyone may sue anyone for anything!  (how delightful)

    Heard about this.

    Last "funny" case was of one UStupid who sued the "Red Bull" because he had not got wings ...

    In europe, people use to laugh about such incidents.

    But back to the topic - automakers here do not fully control the "after sales market", i.e. accessories sold separately. And in most cases, this items are not crucial anyway (even the car radio began to annoy me a few years ago ...)

    But that is a case to discuss with lawyers/lega advisers.

    I only know for sure that most automakers here insist on -40 ... +125°C for any MCU in their control units.

  • 0 in reply to f. m.
    Guru 47900 points

    f. m. said:
    ...that is a case to discuss with lawyers/legal advisers.

    Believe that's well stated.  Poster (and others) must recognize that, "Ignorance of the law does not serve as an adequate defense!"  Prior to the sale of (even) serial #1 - competent firm should be consulted - & advice followed.

    Comment on -40°C...+125°C Control operation is usual for "engine compartment based" MCUs.   My past semi firm received waivers for those MCUs destined for passenger compartment and/or other - less hostile - vehicular locations...

    The number of MCUs (now) in even an average auto is astounding - and is expected to grow - as is the opportunity for (well considered) & positioned aftermarket devices.

  • 0 in reply to cb1
    Intellectual 980 points

    Yes, I understand that this would need some lawyer consultation and don't expect to get it here (it's an engineering forum after all). But I'm perfectly fine with getting just informal opinions and even rumors - it's still useful and interesting to hear.

  • 0 in reply to Lacho Tomov
    Guru 117855 points

    Lacho Tomov said:
    I'm perfectly fine with getting just informal opinions and even rumors

    Faint that praise! 

    In defense of f.m. & this reporter - temp. spec & automotive organizations we've ID'ed (clearly in your behalf) - may rise (bit beyond)  "informal opinion/rumor." 

    Photo below reveals our deliverable for famed Italian auto maker (and racer) - digital dash - our (earlier) firm designed/developed more than 2 decades past.  (photo below may "pierce" assertion of "opinion/rumor!")  Displays included, "Planar Gas Discharge, Vacuum Fluorescent, & Incandescent."  That circular bar-graph (Tach - center of dash) appears as, "Liquid/flowing Fire" near 180° view angle - extremely compelling.  (we sold a ton to power stations - many "nuke.") 

     

  • 0 in reply to cb1_mobile
    Intellectual 980 points

    Umm I don't mean to say that people here don't know what they're saying, but more like that I don't expect to get into the deep "lawyer" waters. I'm not a native speaker, which may sometimes cause confusion in my writings :)

  • 0 in reply to Lacho Tomov
    Guru 117855 points

    Early - "proactive" legal consultation most always saves time, money, heartache.  Two here have so advised.

    That said - the organizations & regulation referenced may prove of great value.  (surely have for our tech group - for years)  The more info you can glean - and provide to your legal team - the better their understanding & advice - and (often) legal charges may reduce.

    Believe this horse well beaten - farewell...