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GrumpyOldPizza / ArduinoCore-stm32l0

Arduino Core for STM32L0
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booting takes 4-5 seconds #28

Closed tve closed 6 years ago

tve commented 6 years ago

If I write a sketch that turns the LED on as the first thing in setup() it takes 4-5 seconds after the upload completes for the LED to turn on. What causes this delay? (I'm using a generic L082 board.)

GrumpyOldPizza commented 6 years ago

Good question. A supported board with the LoRa module typically goes through calibration of LSI / HSI16 and LSE. But this should not take more than half a second.

But to be honest I never benchmarked boot time.

On Fri, Aug 3, 2018, 10:08 PM Thorsten von Eicken notifications@github.com wrote:

If I write a sketch that turns the LED on as the first thing in setup() it takes 4-5 seconds after the upload completes for the LED to turn on. What causes this delay? (I'm using a generic L082 board.)

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tve commented 6 years ago

OK, I'll dig in a see where the time goes...

The board I use has LoRa but not with a TCXO, so nothing to calibrate with :-). I've been using the stm32l0's with Forth and totally bare-bones (i.e. from datasheet&refman) and I've not used Arduino on ARM, so I'm a bit lost in the sea of #defines and overrides... I like that most of your code is on the bare HW as opposed to layers upon layers of some standard code :-). Do you hang out in some chat room (gitter, slack, ...) where I could ask you some quick questions? I can dig through the code but for some stuff you can probably point me in the right direction off the top of your head.

I've started to add support to build sketches with platform.io and also a Generic-L082CZ variant in my fork https://github.com/tve/ArduinoCore-stm32l0, dunno whether you're interested in a PR.

tve commented 6 years ago

I believe it had to do with me having #define STM32L0_CONFIG_LSECLK 32768 but not having an external crystal...

GrumpyOldPizza commented 6 years ago

The code is not really working without LSE. If you don't have that populated, you might as well stop and rework your hardware.

On Sun, Aug 12, 2018, 12:57 PM Thorsten von Eicken notifications@github.com wrote:

I believe it had to do with me having #define STM32L0_CONFIG_LSECLK 32768 but not having an external crystal...

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tve commented 6 years ago

Can you elaborate? Are you talking about the RTC code or which portions?

GrumpyOldPizza commented 6 years ago

RTC and LPTIM use essentially 32768Hz. RTC is used for pretty much all timing related facilities. It requires a synchronous divider of 2048. That is simply not doable with LSI. Even worse, LSI is nominal 37kHz, but could be anywhere between 26kHz and 56kHz.

On Sun, Aug 12, 2018, 3:19 PM Thorsten von Eicken notifications@github.com wrote:

Can you elaborate? Are you talking about the RTC code or which portions?

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tve commented 6 years ago

I see, thanks for the info.