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  1. #81
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    Re: Embedded project needs devices which can work continuously at +125 degree C

    Hi,

    To be honest, I'm not sure what MUX_E1 is supposed to do. There is no need to disable all the CS signals, only to enable the one being used before the clocking starts.
    MUX_E1 is the global CS (or enable) whereas A, B, C are the address lines. With this configuration you don't need to modify the SPI code (independent of how many SPI slaves are connected), you just need to set the address lines before you start a SPI transfer.
    This is the way I do all my designs.

    Your code works but still I have to subtract ambient temperature reading from MAX31855 (TCx) readings to get correct readings
    Generally thermocouple is a relative temperature measurement with respect to cold junction temperature. To get the correct temperature of the thermocouple point you need to ADD ambient temperature.
    Maybe this already is done in you thermocouple measurement ICs. I didn't read the datasheet, but you should do.

    It makes no sense to SUBTRACT ambient temperature.

    Klaus
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    Re: Embedded project needs devices which can work continuously at +125 degree C

    Can I use this NOR SPI Flash for my ESP8266EX (WROOM-02U) circuit ? Earlier I had chosen EverSpin NAND SPI Flash. What is the difference between NOR and NAND SPI Falsh chips ?

    Can a NAND SPI Flash be replaced with NOR SPI Flash chip ?

    Find attached.



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    Re: Embedded project needs devices which can work continuously at +125 degree C

    From the outside there is very little difference and they will perform identically. Have you considered how you are going to program them? You will at least need to load a bootloader program into the flash before it can be used unless you are programming everything in assembly language.

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    Re: Embedded project needs devices which can work continuously at +125 degree C

    Okay, I am programming in C for ESP8266EX and have already done that and tested my ESP8266EX code with mikroe WiFi ESP Click after uploading the firmware (.bin) file to it and it is working fine.

    Do I have to make any changes to firmware if I use NAND or NOR SPI Flash or will the Esprissif ESP8266 firmware upload tool will do what is needed ?

    I used Esprissif's ESP8266 firmware upload tool to program my mikroe WiFi ESP Click with the firmware that I have written.

    Here there are 2 things. Initially we will test the hardware and ESP code with mikroe WiFi ESP Click (WROOM-02) and if it works fine then we will put the ESP8266EX circuit on a small 4 layer PCB similar to mikroE WiFi ESP Click which uses all components with max operating temperature of +125 deg C.
    Last edited by baileychic; 25th February 2019 at 09:57.



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    Re: Embedded project needs devices which can work continuously at +125 degree C

    As long as your flash meets the timing specifications you can use any type equally well.

    What concerns me is your software. There is a big difference between ready made ESP WiFi modules and the bare ESP8266. The modules already have a bootloader inside their flash so you can put them into programming mode and feed your application software through the ESP serial port. If you start with a completely blank flash I don't think you can program it at all. I may be wrong but I think you may have to use a discrete programming device to program the flash in order to get the normal in-circuit programming state.

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    Re: Embedded project needs devices which can work continuously at +125 degree C

    Are you sure that ESP8266 supports serial NAND flash? Any reference in hardware manual?


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    Re: Embedded project needs devices which can work continuously at +125 degree C

    @FvM

    I am not sure. I couldn't find the part number of the SPI Flash chip used in WROOM-02 and we had selected EverSpin SPI NAND Flash. I had also provided its link here and had asked whether it was compatible.



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    Re: Embedded project needs devices which can work continuously at +125 degree C

    we had selected EverSpin SPI NAND Flash
    Which part? I'm only aware of MRAM (magnetoresitive nonvolatile RAM) manufactured by Everspin.

    I couldn't find the part number of the SPI Flash chip used in WROOM-02
    Yes, there's no part number reference. Some ESP8266 dev-boards are referencing FM25Q32 and FM25Q16 (industry standard QSPI NOR flash).

    You could also use new ESP8265 with embedded 8 Mbit flash.



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    Re: Embedded project needs devices which can work continuously at +125 degree C

    @FvM

    ESP8265 can operate at +125 deg C ?

    We are using ESP8266EX and it can operate at +125 deg C but it was difficult to find SPI Flash chips which operate at +125 deg C and we only found EverSpin and Micron chips for that.



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    Re: Embedded project needs devices which can work continuously at +125 degree C




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    Re: Embedded project needs devices which can work continuously at +125 degree C

    They are standard QSPI NOR flash, I assume yes.


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    Re: Embedded project needs devices which can work continuously at +125 degree C

    Hi, all,

    Given all the activity this thread has, I tasked one of our freelancers to write an article around it. Check it out here: https://www.microcontrollertips.com/...bedded-design/

    cheers,
    Aimee K
    Editor, EEWorld (WTWH Media)


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    Re: Embedded project needs devices which can work continuously at +125 degree C

    Thank you for making the article. I will read it in detail later and reply to it.

    As of now Client needs a final change to the power supply circuit.

    Now, he is going to use this battery.

    https://in.element14.com/saft/mfn747...ick/dp/1292971

    Single battery with boost regulator will be used to get 5V from 3.6V after any diode drops.

    https://www.ti.com/lit/ds/symlink/lm2622.pdf

    For battery charging I was advised to use battery management IC.

    So, how should I proceed in making the new Power Supply circuit ?

    I have no experience with using/designing battery management IC circuits and boost regulators.

    I need to get 3.3V for PIC18F circuit which is already done in the attached circuit.

    I need to get 5V after any diode drops from 3.6V battery voltage boosted. BLDC fan max current is 250mA and Vmax is 6V.

    Peltier is going to give only 5V.

    So, how should i modify the attached circuit to get my Client's new requirement ?



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    Re: Embedded project needs devices which can work continuously at +125 degree C

    Nice one Aimee, please thank the author.

    The listed battery is rated to a maximum of 70C and has a warning of electrolyte leakage beyond 100C. It certainly isn't suitable at 125C.

    Note the warning on the label "Do not incinerate" !

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    Re: Embedded project needs devices which can work continuously at +125 degree C

    We are using ESP8266EX and it can operate at +125 deg C but it was difficult to find SPI Flash chips which operate at +125 deg C
    The OP has been exaustively alerted during the course of this thread on how inconceivable it is to think about making a system to work (burn) within an oven. More than once it has ben mentioned the device self heating as a source of additional increase to the device stationary (environmental) temperature, reaching far beyond the one stated in datasheet, therefore it is notorious to see how much this thread keept alive, at least with the same title, which could bring the wrong assumption that it is even feasible ("...devices which can work continuously at +125 degree C..."). It is worthy to review the notion of temperature rating of devices as an indication of how close it would be to its physical limits, and let's agree, 125oC is a lot, even for critical applications such as military and industrial; Some of the parts on the list has a not so small thermal gradient, soo one would expect to see a design on this scope made with CAD thermal simulators considering details of monted board and box geometries, etc...
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    Re: Embedded project needs devices which can work continuously at +125 degree C

    Client will test the circuit with above Ni-CD battery within 80 deg C. He will not use it at +125 deg C. He has already found another battery which can operate at +125 deg C and he is importing it but he said it will take 1 to 2 months. Till then he will use and and test the above Ni-CD battery at 70 to 80 deg C in the device.

    So, how should I proceed in making the new power supply circuit ?

    Should I just remove the LM2595-5 regulator and use LM2622 boost regulator to get 5V for fan from 3.0V to 3.6V of battery and then use another battery management IC like BQ24401 to charge the battery ?



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    Re: Embedded project needs devices which can work continuously at +125 degree C

    Hi,

    I have no experience with using/designing battery management IC circuits and boost regulators.
    There is no simple answer to this.

    But the IC manufacturer provide a lot uf useful tools like
    * online selection guides
    * online and/or downloadable simulators, some of them calculate the part values and ouput a BOM.
    * datasheets
    * application notes
    * design notes
    ...
    Regulator: If you are looking for low power dissipation you should look for synchronous (rectifying) boost regulators.

    Charger IC: This seems to be a very old one... with many external parts. There will be more modern ones. Here also: Check for low power dissipation.
    btw: The charger IC uses an NTC to check battery temperature and to stop charging according temperature. Check if this will work at high abient temperature.

    Klaus
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    Re: Embedded project needs devices which can work continuously at +125 degree C

    Klaus raises a very good point: the only reliable way to detect when a NiCd cell has reached full charge is by a small increase in temperature when it stops storing energy and starts dissipating it instead. Almost all charger ICs have temperature monitoring inputs for this purpose. If you run it at constant high temperature it may not be able to detect the increase and cut the charging current when it should. There is a combined risk from the high temperature itself (even 80C is above rating) and the additional heat generated from the charging process and it failing to stop charging that could make the battery quite dangerous. I have witnessed exploding AA size NiCd cells that embedded their center electrode in a wall, you wouldn't want to be nearby!

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    Re: Embedded project needs devices which can work continuously at +125 degree C

    Can I use one of these boost converters to get 6V (5V output after diode drops) and 1.2A output current from 3.0V to 4.2V input voltage ?

    https://www.analog.com/en/products/l...oduct-overview

    https://www.analog.com/en/products/l...oduct-overview

    If yes, how to choose the required component values ?

    Can I use this battery charger IC to charge Nni-CD 3.6V battery form Vin (Peltier V) 5.0V. Charging voltage will be 4.2V and Charging current will be 450mA as battery is 4500mAh type.

    https://www.analog.com/en/products/ltc4059.html

    - - - Updated - - -

    Can I use this for battery charger ?

    The datasheet doesn't provide information whether this can operate at +125 deg C but this page says temp range +125 deg C.

    https://www.analog.com/en/products/l...duct-samplebuy



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    Re: Embedded project needs devices which can work continuously at +125 degree C

    Quote Originally Posted by baileychic View Post
    The datasheet doesn't provide information whether this can operate at +125 deg C
    Why do you insist on feeding this thread with useless information, giving the impression that you did not even take a time/interest to carefully read the datasheets ? There clearly states the allowed temperature:

    "The LTC4059E/LTC4059AE are guaranteed to meet performance specifications from 0°C to 70°C. Specifications over the –40°C to 85°C operating temperature range are assured by design, characterization and correlation with statistical process controls."
    There you can see 125oC as storage temperature as well as junction temperature, which means that the environment temperature should lie quite below.
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