Wiced_enable_mcu_rtc / wiced_disable_mcu_powersave

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Anonymous
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What do the above defines really mean?

I am trying to use the RTC of the STM32F205 the way I would think it should be used.   Somehow it gets set (TBD) and then the device retains time through MCU STANDBY.   It looks like the RTC gets initialized (RESET) if the above is defined.

What do I get and lose by the above defines?  If I want to build a low power battery operated device (which goes to and retains time in STANDBY / wake via the WKUP pin) what do I do?

Thanks.
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11 Replies
Anonymous
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WICED does not currently provide any APIs to work with STM32 STANDBY mode.

We are working on an example application to demonstrate how this would work.

Please explain your use case in as much detail as possible.

What needs to go to sleep and when?

What information needs to be retained?

What wakes the STM32 up?
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Anonymous
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I would be interested in hearing an explanation of those defines as well
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Anonymous
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Attached is a working STM32F2 standby mode example app.

Drop the app at the top of WICED-SDK-2.4.0 official release and use the following build string to build:

snip.standby_mode-BCM943362WCD4 download run

Change BCM943362WCD4 to your own desired platform, but I suggest you run it with BCM943362WCD4 first, just to gain some understanding of what the app actually does.

The application performs the following:

  1. Boots up and initialises WICED
  2. If it boots up out of reset pin or normal power up, initialises the RTC to 1/1/1970 00:00:00
  3. Join to Wi-Fi network (change CLIENT_AP_SSID and CLIENT_AP_PASSPHRASE to your desired Wi-Fi network)
  4. Performs SNTP sync 5. Set the RTC to the NTP time
  5. Perform DNS lookup for google.com
  6. Sends a HTTPS GET to google.com
  7. Deinit WICED
  8. Set RTC alarm to set off 10 seconds later. This can be change by changing SLEEP_TIME_SECOND define up the top.
  9. Enter standby mode. 
  10. Repeat and skip  step 2 when the system exits standby mode

You mentioned that your board doesnt have 32K external crystal. You can uncomment RTC_CLOCK_SOURCE_LSI to use the internal oscillator.

Also, please keep all of the defines in wiced_defaults.h i.e. keep WICED_DISABLE_MCU_POWERSAVE and WICED_ENABLE_MCU_RTC commented.
Anonymous
Not applicable

Hi Jasonrc,

We are currently struggling to get our BCM943362WCD4 to consume less than 1,47mA in low power. We are using the snip.ping_powersave provided with the SDK.

Whilst we keep trying to reduce the power consumption is it possible to get the standby mode example app mentioned in your reply, to see if we can reach lower consumtion figures?

Thanks

Aketza

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Hi Jasonrc,

We are also interested in seeing your example. If extreme powersave can be achieved, this will help us release our product on WICED instead of searching for alternate solutions.

We are hoping to run the product on 2 x AA batteries with 1 minute wakeup for UDP broadcast.

Thanks

mus

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Anonymous
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Which WICED module are you using?

What battery life do you require from 2 x AA batteries?

Note that modules from ACKme Networks are the lowest power WICED modules available on the market today. You may want to consider using these modules if your application needs low power.

Please contact ACKme at http://ack.me/contact for further information.

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We are using Murata Type YD due to space constraints and hoping to get close to 1 year of battery life.

Is it possible to get your suggested code sample to try?

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Jason,

will ill you be able to send me the example you mention above?

thanks

mus

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Anonymous
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can you elaborate on size constraints?

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Hi Nick. The requirements didn't change since we last talked. Give me a call if you want to discuss.

Sent from my iPhone

Mustafa Oransel

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Anonymous
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Mustafa, i didnt realise that was you till i saw your last name. I cant remember the details of your size requirement because i had to give up my records when i left microchip.

I have something quite small in the works but it's not released yet. We can talk offline next week.

Nick

Sent from my iPhone (expect some funky spellings)

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