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Use FRAM to store time counters, eliminate RTC backup. #29

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bigjosh opened this issue Dec 12, 2023 · 4 comments
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Use FRAM to store time counters, eliminate RTC backup. #29

bigjosh opened this issue Dec 12, 2023 · 4 comments
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enhancement New feature or request

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@bigjosh
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bigjosh commented Dec 12, 2023

So much simpler code. Gets rid of those problematic and expensive backup caps.

Only user impact is that time pauses when there is no battery power, which seems correct.
@bigjosh bigjosh added the enhancement New feature or request label Dec 12, 2023
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bigjosh commented Jul 8, 2024

Seems maybe we can not simply remove the backup CAP?...
image

Have a request into microcrystal now to see what that is about.

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bigjosh commented Jul 8, 2024

We can always just sub this for the CAP at 1/2 a cent...
https://www.digikey.com/en/products/detail/stackpole-electronics-inc/RMCF0805JT10K0/1757762

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bigjosh commented Jul 10, 2024

Ok, Microsemi says "You can not leave a CMOS input floating." But I am sceptical. According to the docs, while this is an input in the sense that a current is flowing into a transistor, this is not a gate input. But at least for now, we will put the resistor in since it is low risk. We can always omit it later.

bigjosh added a commit that referenced this issue Jul 10, 2024
@bigjosh
Remove RTC backup CAP from BOM
e9f4ca2 
Still need to update firmware to continuously track elapsed time as per #29.
@bigjosh bigjosh mentioned this issue Jul 15, 2024
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bigjosh added a commit that referenced this issue Jul 20, 2024
@bigjosh
Functionally complete and working with new persistent memory counters…
0329562 
… rather than RTC backup

Closes #29 , #30 , & #35.

Overall current draw is still less than 2uA.

Currently we unlock/lock the info FRAM where we keep the counters each time we update them, which is once per minute. This uses slightly more power than just leaving them unlocked, unknow if there is any safety benefit.

Lightly tested and seems to work, but big changes so needs way more testing.
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bigjosh commented Jul 21, 2024

Closed with 0329562

@bigjosh bigjosh closed this as completed Jul 21, 2024
@bigjosh bigjosh mentioned this issue Jul 27, 2024
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bigjosh referenced this issue Jul 27, 2024
@bigjosh
Merge pull request #42 from bigjosh/pausable
e900bf5 
New persistent storage of time since launch count pauses when batteries are out, then resumes when back in. Omits RTC backup capacitor.
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