TinyExtender project

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FanOfHue
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Joined: 06 Oct 2018, 10:08

TinyExtender project

#1 Post by FanOfHue » 08 Oct 2019, 16:28

Don't know if anyone still working on the letscontrolit NodoTiny repository, last commit 3 years ago :shock:
But found some nice code stuff that helped me create a TinyExtender project, similar to the Pro Mini Extender and using a similar plugin and protocol.

Currently using it as a test device that boots the doorsensor every hour and measuring the battery voltage:
DoorSensorMod.png
DoorSensorMod.png (296.62 KiB) Viewed 541 times
With the ATTiny85 chip glued to the board on the left side, a header to do future firmware upgrades, connected to the reed relais to boot the machine and connected using I2C to the ESP module. This way the ESP can configure the TinyExtender. Config is stored inside the ATTiny85 EEPROM. I can set the boot delay this way but other things would be possible. All this still fits into the original housing.

It might also open ways to use the doorsensor for other purposes, maybe a temperature sensor, a level alert device or something. All running on batteries.

Nice thing is that the doorsensor has build-in power control using a step-up converter that provides a clean 3.3 Volts to the ESP even with a battery voltage that is much lower.

Wonder what battery life will be when booting it up every hour.

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enesbcs
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Re: TinyExtender project

#2 Post by enesbcs » 08 Oct 2019, 22:38

FanOfHue wrote:
08 Oct 2019, 16:28
...
doorsensor has build-in power control using a step-up converter that provides a clean 3.3 Volts to the ESP even with a battery voltage that is much lower.

Wonder what battery life will be when booting it up every hour.
Yes i am wondering also, as i am afraid that the step-up converter may drain the battery very soon...

For MiniExtender-like projects one suggestion: never use slow functions such as analogread() directly in ISR functions, use global variables instead to avoid blocking, something like this:
https://github.com/enesbcs/ESPEasySlave ... tender.ino

FanOfHue
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Posts: 58
Joined: 06 Oct 2018, 10:08

Re: TinyExtender project

#3 Post by FanOfHue » 09 Oct 2019, 12:01

I'm not afraid of that part, as the entire step-up converter is "power-controlled" by the MCU.
The MCU and ATTiny85 are running on direct battery voltage.
The ESP runs on the step-up converter and it's powered down when not in use.

I'm more worried about the high current consumption of the ESP and the duration of each wake-up.
It takes about 5 seconds.

I'm also checking out a 'hack' solution that happytm brought to my attention, abusing the Wifi-probe to send 5 bytes of data to another ESP running as AP.
It works and it's really fast. But no security, or just security by obscurity. Could still be useful for low-risk operations.

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