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2540 real but full of hype.

Mark Van Dareen
Prodigy 190 points
Other Parts Discussed in Thread: CC2540, CC2530

Well, I got some samples of the chip so it is real. However their AN092 indicates a  3032 battery life span of 330 days :)

What a joke! They have simulated the real life operation with three resistors and a switch and come out with this incredible number.

As one that works for the last five years with this stuff, I _know_  that the real battery life, for a device that consumes 29mA,  is only 33 days. Especially when you can not control what brand of battery the customer will buy.

In their  document there is no mention of synchronization (re-sinchronizarion)  time, there is no mention of recovery after congestion drop out time etc etc etc.

MARK

 

 

  • TI__Expert 4060 points

    Hi Mark,

    We do appreciate constructive feedback on our coin cell white paper. One of the reasons we did these tests (we actually spent some months on them, as even accelerated testing took two weeks to complete) was that there was so little information available on the actual behavior of Lithium coin cells. If you could point us to a source of more information about the effects you mention, that would be very useful.

    BTW, any evidence to prove your 29 mA=33 days number? I know Polar made a CR2032-powered heart-rate belt that uses classic Bluetooth, and this doesn't have that bad battery life.

    Best regards,

    Karl

  • in reply to Karl T.
    Prodigy 190 points

    Hello Karl.

     

    I believe you are missing the point. This is not about the battery but about the lousy simulation of your device operation.

    Is this the best that the TI gurus can come up? Please tell me that the publication of the .xls document was the work of a first grade student and it should have not being published. Perhaps TI has forgotten the audience it addresses. Some of us really do know this stuff. To tell the truth I felt insulted reading your paper. Who do you thing are you selling your stuff?

    So, you will welcome our hard earned IP. And you want it for free :)

    Well Karl, in 2004 we had to abandon a lucrative contract because we did just that. You took the information, passed along the third party (some Russian nondescript company) that was producing a symbiote firmware for your  DSP (the CST) and we were just wiped out. I get burned once only, so Karl, what is it in for us if we share our knowledge?

     

    BTW, what is your name, your position in the company and are you supposed to ask this question?

     

    Sincerely,

    Mark Van Dareen

    General Manager

    Sand Wave LLC.

  • in reply to Mark Van Dareen
    TI__Expert 4060 points

    Dear Sir,

    I believe we may be discussing two different documents. WP001 Coin Cells and Peak Current draw looks into the effects of high peak currents on coin cells. As stated in this document, the measurement apparatus is indeed based on resistors. AN092 Measuring Bluetooth low energy power consumption is based on measurements of the actual CC2540 device in a connected state. A resistor is used to convert current to voltage for display on an oscilloscope. It is clearly stated in the introduction to the latter document that it makes no claims to be an absolutely exhaustive analysis of BLE power consumption, but focuses on the connection state only, and that actual results may differ depending on the application scenario.

    As I mentioned earlier, we do welcome constructive critisism of what we do, but I think you are far overstepping the boundaries of what could be called constructive critisism here. I will not accept harassement of my fellow TI colleagues.

    We are by no means after your IP, but if you make a claim, it is commonly expected that you present some facts to back it up. If you feel that using a resistor to convert current to voltage is a poor measurement technique, then please state this and explain why without resorting to insulting people.

    This is a public forum. In these kinds of places, it is generally expected that members contribute constructively. If you don't want to do that, then this is perhaps not the right place for you.

    Best regards,

    Karl H. Torvmark

    Strategic Marketing

    TI Low-power RF

  • in reply to Karl T.
    Prodigy 190 points

    Dear Mr Torvmark.

    The “Gaddafi” doctrine will not work with me. You kan not ban me just because you do not like what I have to say. This will be totally un-American J

    Take it easy. I am 75 years old and I learned the hard way that burying your head in silicon is not healthy at all J

    Going back to our discussion. I am sorry you see my message as non-constructive. I was willing to live with the horrendous current absorbsion on RX of your device but when I saw the AN92, it just ticked me off.

    So, you say you are in Strategic Marketing. You have not given me your title. As you recall, there were three questions in my previous message. You responded to just one.

    OK. You want constructive criticism? Here you go.

    First. Exaggerated current consumption in RX Mode. Please justify why.

    Second: You do not offer a scaled down BT Stack.

    Third: It seems to me that your BLE has no target market. Just a “me too” device. If you are in the sensor market then why incorporating a USB?

    Forth: what will compel a designer to use your device against any other? What is your edge?

    Fifth: can you share on this forum, the HLDC for the device?

    Sixth: where will your money coming from? From selling your device or from selling your EVAL kit? Your tools should be free and avoid third party extensions! I am a MSP430 user for many years. You telling me now to purchase a new development tool? WHY? Just here you lost half of your customers L

    And I could go on and on and on. In conclusion, it appears to me that the cc2540 is misplaced in the markets. In last instance the user of our gadgets (willingly or not we are in the gadget market) is not interested how his toy is working. We are a “turn key” society, remember? All the we want is low price, possibly for free J , and low maintenance cost!

    Who will buy my gadget if I’ll tell them that he has to replace its battery say, every 3 months?

    Because you asked, here is a tip how to test your battery life. I call it the 1000T.

    Take a volume of 10 by 10 by 10 meters. Divide it in one meter cube subdivisions. On every side of a cube you install an old vinyl record player. On is turntable you Velcro one of your devices. The devices are paired such a way that they are separated by most distance possible.

    All devices carry the same test Firmware. Turn on the turntables. The devices will attempt to connect to their peers periodical, pass a sixteen byte payload data and keep track of successes and failures with time stamps. Keep track of these activities outside the kube and keep going as long there is one device still operating. When all batteries are exhausted, remove the devices, download their accumulated data and analyze it on a decent computer. NOW you will be able to tell how long your battery will last. This is how we do it at Sand Wave! In the Empire State Building where we have on the roof 10MWats of diverse RF frequencies transmitters installed! This is where our 33 days of battery life comes from!

    Is this enough of constructive criticism? Do you want me just to go away or to stay J

    Mark Van Darren

    Sand Wave LLC

    　

    　

    　

    　

    　

    　

    　

    　

    　

    　

    　

     

    　

     

  • in reply to Mark Van Dareen
    TI__Expert 4060 points

    Dear Mr. Van Darren,

    We are not for sensorship, as you can see this thread is still alive. I'll leave it to the readers to decide if there are any Gadaffis here. I do not have an issue with what you have to say, but rather with how you choose to express it. With that said, this conversation is changing into something more related to facts than with name-calling, and that is definitively an improvement.

    If you define my title as what it says on my business card, then actually "Strategic Marketing" is true. I am basically doing product definition and product strategy, "Systems Engineer" or "Strategic Marketing Engineer" are some terms in use in various parts of TI when talking about this role.

    I'll try to summarize how I see the main points of value proposition of the CC2540 as I see it:

    • CC2540 is the only flash-based SoC (MCU+RF) for BLE on the market, providing cost and size benefits compared to multi-chips solutions
    • We believe our BLE software stack is the most mature, robust and full-features single-mode BLE stack on the market
    • CC2540 was available to customers around 6 months before any other single-mode BLE products (meaning we have had more time to work with customers and gather feedback. I must add that this feedback has generally been more positive than your assessment.)
    • Pin-compatibility with other RF circuits like the CC2530 (ZigBee), allowing developers who are working with multiple standards to work easily with one platform.

    Thanks for your feedback points, I wanted to add some detail to some of them:

    1. The RX current is in line with what we have on our ZigBee devices. I think the major point of our appnote is that you cannot just focus on this number, there are other currents that are important as well (MCU current, TX current, power-down current, as well as currents and time for switching between modes).
    2. We do offer a single-mode BLE stack. Not sure if you are thinking about a stripped down version of this or of the full "classic" Bluetooth stack. For the first option, this is something we are looking at (role-optimized versions). For the second, there is a different group in TI targeting "classic" Bluetooth, there's a separate forum for this.
    3. I don't agree with your assessment here. As I mentioned earlier, we were first to market, which I think rules out being "me-too" in the first place. Second, I think we have some important differentiators as listed above. With regards to the USB, this was added to the device because we believed that early on there would not be a lot of devices to talk to. This seems to be been jusified, as of today there are no BLE USB dongles available on the market other than those based on the CC2540. Without USB, we would have to rely on a UART to communicate with PCs, not exactly in line with what you would expect of development in 2011. If you don't need it, just connect those four pins to ground and pertend you didn't see the description in the datasheet... :-) As for hitting the target market, kind of the challenge with addressing a new market like the BLE market is that nobody quite knows what the killer application will be. It therefore makes sense to start out with a quite general device and then optimize once you do have a good idea of what your customers actually want. 
    4. Again, I would point to the list above.
    5. Not sure what your acronym means, but if you are referring to a High-level design document, then that is confidential information and cannot be posted in a public forum.
    6. I think your critism here is not fair, as our development kit is the lowest-cost BLE development kit on the market at $99. This price just covers our direct HW costs in making the kit. Unfortunately, there are no good open-source free compilers for the 8051, and creating one from scratch is a relatively large undertaking (and as you allude to, we do make our money making chips and not creating compilers). In an ideal world, yes, we would have a free compiler. As to why the 8051 was chosen rather than MSP430, there are a lot of reasons for that, most of which cannot be discussed in a public forum. Looking at the rest of our portfolio may offer some hints.

    As for test metods, one issue is that applications vary widely in how the chips are used. So, once you have a usage scenario and an implementation, you can test the way you describe. Unfortunately, we have to support hundreds of applications, so we cannot do the same. What we have chosen to do, is to put together one, generic scenario (we'll probably do more in the future), tell people how we came up with those numbers, and then give people a way to change the assumptions (which is why we put it into a spreadsheet) and make some approximations. I'm sorry if you expected something different. I do challenge that you state 33 days as if was a general fact of BLE, while in truth it is only true for your specific usage scenario (with certain connection intervals, advertising intervals, usage patterns, payload sizes just to mention a few of the variables involved). You could easily come up with different scenarios with vastly different battery life. For example, some applications only require communication at very seldom intervals, where power-down current and battery leakage would easily dominate). Going the other way, if you are transmitting data almost continously, then the TX current would dominate and you probably couldn't run the application on a coin cell at all. I could easily see the span of coin-cell battery life using BLE as varying from as much as 10 years (shelf life of the battery) to a battery life measured in minutes depending on what you are trying to do. We are planning to add some more detail to our model, including support for calculating the impact of advertising (which is what would happen when the link is broken).

    Anyway, thanks again for the feedback, and although we don't seem to agree on a lot of points, I do respect your point of view.

    Best regards,

    Karl

  • TI__Genius 17975 points

    Hi Mark-

    I'm the author of application note AN092, and in fact am not a "first grade student", but rather an experienced engineer. I'm sorry if you don't agree with the document; however as clearly stated on the first page:

    "Note that the results presented in this document are intended as a guideline only. A variety of factors will influence the battery life calculation and final measurements. Measurements should be performed on customer hardware, in a controlled environment, and under the target application scenario."

    Simply put, there will never be any laboratory test that will exactly simulate a real-life use-case. The intention of the application note is to go through one simple example application scenario, explain how to perform measurements using an osilloscope, and give details on the how to calculate the average current and battery life for that scenario. The spreadsheet is provided to simplify the calculations. The idea is then for you to repeat this experiment under your own application scenario, and use the blank worksheet to enter in your own measurements. The spreadsheet also leaves extra columns for you to put in your own additional processing tasks, and include those in the calculation.

    In my example scenario, I make the following assumptions (all clearly stated in the document):

    -The devices are connected with a 1s connection interval and no slave latency

    -No application data is being transmitted in either direction

    -The two devices remain in a constant connected state

    -The battery capacity is 230mAh

    Under these conditions, I think that the 330 days of battery life is valid and accurate (note that the average current is 29ua, not 29mA; the battery life would be much, much shorter if that were the case). You are absolutely correct that factors such as re-transmissions and switching between connected and advertising states will result in higher average current; however in many BLE scenarios this will not make a significant difference. This is because in scenario such as the one above, the two devices must wake up and communicate once per second, regardless of whether any data is being transmitter, received, or re-transmitted. Certainly the processing time will be slightly longer when dealing with re-transmissions; however if you assume a PER of less than 1% (a fair assumption with proper RF design) then this should have minimal effect on the average current.

    The CC2540 product page (http://focus.ti.com/docs/prod/folders/print/cc2540.html) has some great documents on 2.4GHz antenna selection. For anyone who does not have the RF expertise to design their own antenna, use of a module is a great way to get up and running

    In addition to having proper RF design, use of proper connection parameters as required by the application will allow for optimal power performance. Information on BLE connection parameters can be found in section 3.3.1 of the SW Developer's Guide (http://www.ti.com/litv/pdf/swru271).

    While I have not had the opportunity to actually leave a device operating for 330 days, I have performed similar measurements and calculations and have run actual experiments using a much shorter interval. The result of these experiments is that the battery lasted to within a few percent of the predicted life. I would encourage anyone who has run this experiment under their own application scenario to post on our E2E forums, and share their results.

  • in reply to Willis1
    Prodigy 190 points

     

    Dear Willis,

    First, pelesed to meet you. Second, I believe that you have forgotten what you’ve did or perhaps we are not specking about the same document. Gere is a copy of the bottom line of your(?) document.

    I think you are saying NINE THOUSAND days and not three hundred. Is this correct? This amount to three years of operation J

    I know that engineering is always under presure to create documents that put the best light on the Marketing decision blunders. I have been there, I’ve done this. For IBM, for Intel, for Racal for Siemens etc etc etc. And the engineers are bending low because they have a family, a mortgage or they just do not care J

    You are preaching to the choir Willis. I did so too… But I got so badly burned that since 1980 I have become my own boss. NO MORE BENDING! In case of a problem I can blame only my self but it is really rewording when it all come togheter J  You should try it too :)

    OK….

    What I hear from you and Karl is disheartening. What you realy say is so:

    “Mark, please give us $99 because we do not know how our product will behave in your application. We do not have any complete functional data. We do not have a Functional Worst Case Scenario. It is up to you to spend some $50000 to make a prototype and decide if it fits or not your requirements.!”

    Is this what you are telling me Willis? Karl?

    You know what Willis, I’ll turn it around on you. Send me 100 free Kits.

    I’ll make the test and then you have to pay ONLY $99 for the data.

    Agreed?

    I am customer, no , a fan of TI, for a long time but what I hear here is highly uncharacteristic. I do not know if this is a sign of changing time or the way engineering is done nowadays. One think is clear. “Something smells in Denmark.”

     

    Mark

  • in reply to Mark Van Dareen
    TI__Genius 17975 points

    I have full confidence in the CC2540 and (Bluetooth low energy in general as a standard) and as an engineer I personally stand by everything stated in the application note as well as in my previous response.

    I don't really understand your last message- we have never claimed 9,000 days of battery life, and I don't know where the three years that you mention comes from. If you don't believe us, no one is forcing you to purchase a kit. Among those who have already purchased kits, many have developed their own software are happy with the results.

    As a standard, Bluetooth low energy has a lot of momentum right now and could become a game-changer in the consumer/mobile industry. This isn't just because of the power claims in one application note, but rather because of the beliefs from an entire industry that is moving forward with the technology.

    It doesn't seem like anything that myself or anyone else from TI say will change your mind or your attitude towards our product, so I'll just leave it at that with regards to your opinions. I know that others reading this are smart enough to decide for themselves whether the CC2540 / BLE is right for them rather than skeptically assuming that all of this is just some kind of big marketing hoax.

  • in reply to Willis1
    Prodigy 190 points

    Willis, Karl,

    I already spent to much time on this subject, so I will make it short and sweet.

    Working for over 30 years with TI I come to expect excellence from you and I got it %99.99 of the time.

     Somehow, TI stumbled this time. I strongly believe that there is a lot of improvements to be done in the way this part is handled. After all you are “TI” not a third rate company.

     Please forgive my bluntness but a cold shower now and then is better than “constructive criticism:)”.

    I will not fall in the trap so many other designers do, just because they think this is the normal way of doing product development.

     Either you give me complete and real data or I walk. About buying? Ohhh well, I rather spend the $100 in buying you a beer.

    BTW, where are you located? I travel intensively so it is possible just to do this :)

     

    Sincerely, Mark Van Dareen.

  • in reply to Mark Van Dareen
    TI__Expert 4060 points

    Mark,

    I'm glad to hear that you in general are happy with TI, and disappointed that you feel that our product is not good. Maybe you will like our future products better.

    I can see that ideally you would like to have all the answers before you start designing (and ideally for free as well), but unfortunately we are not there yet. If you feel that any of our BLE competitors are doing a better job of providing for your needs, please let us know. To my understanding, they are providing less data and more expensive development kits. If somebody else is offering free development kits, I would also love to hear about that.

    We do provide free samples, but of course then you need to pay to make your own boards.

    BTW, I'm located in Oslo, Norway and Willis is located in San Diego, CA. We'll make sure to take you up on the $99 beer offer if you should stop by on your travels. I'm sure $99 will buy a lot more beer in San Diego than in Oslo...

    Best regards,

    Karl

  • in reply to Karl T.
    Prodigy 10 points

    I suspect that Mark is, in reality, a annoying flammer, present on other websites...  Of course, other name but the same style!

    He, maybe, wants just to receive the free application boards!

    Keep it up TI! You're doing a good job!

    Regards,

    Adrian

  • in reply to Adrian Florescu
    Guru 18595 points

    This is very annoying!

    .

    ..

    ...

    .

    I visited Oslo two years ago and you could barely buy 5 beers with $99.

    :)

    On the other hand, as far as I know the CC2540 is Bluetooth SIG compliant so I guess we could go and complain to more than 14000 member companies that TI is wrong and they should not launch to the market any other product because they are a bunch of villains. In fact, if you write TI backwards, you get "IT", the famous Stephen King demonic character, so I think we do not need more evidence.

    Finally, if you are giving development kits for free, I want one of them :)

    PS: seriously, the CC2540DK has some drawbacks, but I think it is a good starting point from 99$.

    PS2: don't try to make me enter this kind of discussion because I think this thread is highly out of forms.