WD8BXS
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RTC Battery quickly discharged
« on: 26. December 2018, 13:50:59 »
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How long is your battery lasting in your McHF?
Mine only lasted about 2 months.
Chuck
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| « Last Edit: 27. December 2018, 13:19:39 by DL8EBD » |
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De WD8BXS vy 73
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WD8BXS
alter Hase
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Re:RTC Battery
« Reply #2 on: 26. December 2018, 22:09:57 »
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I am using the STM32F437VIT7 Processor.
There is no equivalent to C94 on the version 6 UI Board.
The NRST pin from the processor just goes to Pin 2 on the P8 header.
Should I put a capacitor with resistor in parallel top ground from this pin?
Chuck
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De WD8BXS vy 73
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WD8BXS
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Re:RTC Battery
« Reply #3 on: 27. December 2018, 02:19:48 »
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Would the dead battery cause the "Start RTC" selection in the debug menu to go away??
Chuck
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| « Last Edit: 27. December 2018, 02:29:15 by WD8BXS » |
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DB4PLE
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Urgestein
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Re:RTC Battery
« Reply #5 on: 27. December 2018, 11:35:33 »
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Hi,
re NRST: a check in the Reference Manual for STM32F4 RM0090, page 151 reveals that the NRST is internal pulled up to Vdd/Vdda aka Vcc. An external resistor is thus not necessary. There is also a schmitt trigger AND a filter internally, anything less than 20uS pulse will not trigger a reset. So in many cases, no external circuit is necessary. Having said that, long wires to pin 2 or other picked up signal in a transmitter may theoretically reset the processor and in this case a simple RC filter close to the pin may make sense.
In any case: grounding this pin will result in a permanently stopped processor. Energy efficient but not really useful state I'd say.
re RTC Start: Appears if rtc detection code thinks there is an battery connected. The way we do this is not the most reliable way, and it often appears to misdetect the presence. Why: We check if the backup ram remains powered between reboots by reading a value from this memory we wrote there earlier. This is normally only possible if there is an battery present which keeps the backup ram from loosing its contents. However, it appears that the mcHF UI keeps enough energy floating into the backup ram for quite some time after power down and thus our code can be fooled when powering on before the backup ram gets turned off.
73
Danilo
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DB4PLE
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Re:RTC Battery quickly discharged
« Reply #6 on: 28. December 2018, 10:42:11 »
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Hallo Thomas,
möglicherweise würde ein Widerstand auch von direkt von 3.3 V nach GND ähnliche Wirkung entfalten. Im Prinzip sorgt der Widerstand ja lediglich für eine zügige Entladung des Kondensators und hält den Prozessor dann im Reset auch wenn noch etwas Vdd vorhanden ist.
Hier wird https://community.st.com/s/question/0D50X00009XkgBTSAZ/vbat-current-draw-high-just-after-vdd-removed ein ähnliches Problem diskutiert. Könnte es sein, das auch bei unserem Fall der hohe Stromverbrauch nach einiger Zeit nach dem Ausschalten sinkt?
73
Danilo
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WD8BXS
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Re:RTC Battery quickly discharged
« Reply #8 on: 28. December 2018, 18:14:35 »
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So Andreas, are you saying that it is better to just forget about the RTC?
Chuck
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WD8BXS
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Re:RTC Battery quickly discharged
« Reply #10 on: 28. December 2018, 21:23:40 »
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Will do!
I am waiting on a new battery holder first.
de Chuck WD8BXS
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