💬 Capacitive Soil Moisture Sensor

[openhardware.io]

https://www.openhardware.io/view/8250/Capacitive-Soil-Moisture-Sensor

[Anticimex]

Beautiful work

[Puneit Thukral]

Hi great design... If I can suggest one improvement, it would be to burn a minicore bootloader and set BOD to 1.8V so that the batteries can last longer.

[Ron]

@Puneit-Thukral Thanks. I am not quite sure, so correct me please if I am wrong, but I think I am already using the MiniCore bootloader with platformIO. Or do I need to configure to explicitly use the MiniCore bootloaders? Also I have set BOD to disabled as I read somewhere that no BOD can also save battery.

[Anticimex]

@Puneit-Thukral but will the peripherals still work at that level? No use to lower the BOD if radio/security/sensors stop working at a higher voltage.

[Ron]

@Anticimex That was also my thinking behind that. According to the datasheet the ATmega328P works reliably down to 2.4V when using 8MHz.

[Puneit Thukral]

@Ron @Anticimex The radio stops at 1.9V.. so I think its fair to do a BOD of 1.8V.

I used arduinoAsISP to burn bootloader and this is my platformio.ini

[env:program_via_ArduinoISP]
platform = atmelavr
framework = arduino
;  Serial bootloader protocol
upload_protocol = custom
; Serial upload port
upload_port = /dev/cu.*
; Get upload baud rate defined in the fuses_bootloader environment
upload_speed = 19200
board_build.f_cpu = 8000000L
board_hardware.oscillator = internal
board_hardware.uart = uart0
board_hardware.bod = 1.8v
board_hardware.eesave = yes
board_hardware.ckout = no
upload_flags =
    -C
    ; use "tool-avrdude-megaavr" for the atmelmegaavr platform
    /Users/puneit/Nextcloud/PlatformIO/bootloader/tool-avrdude/avrdude2.conf
    -p
    $BOARD_MCU
    -P
    $UPLOAD_PORT
    -b
    $UPLOAD_SPEED
    -c
    stk500
upload_command = avrdude $UPLOAD_FLAGS -U flash:w:$SOURCE:i

[Anticimex]

@Puneit-Thukral yes but for full/specified function, atsha, atmega and any sensor circuitry also need to be operational at that level.

[skywatch]

@Puneit-Thukral When I tested a recent node the radio was presenting to the GW all the way down to 1.64V - so it is always worth trying to see if it works for you or not (ebyte red module).

[sundberg84]

Nice work @Ron . Thinking about getting some of these for my plants.
Any experienced issues, or the PCB and components works good?

[Ron]

@sundberg84 said in Capacitive Soil Moisture Sensor:

Nice work @Ron . Thinking about getting some of these for my plants.
Any experienced issues, or the PCB and components works good?

I had the first prototype running for about 2-3 months and did not experience any issues. The next thing on my todo list is to get an estimation on the total battery lifetime. I would assume that it will be quite good as I did not notice any significant drop in battery voltage over that time. I will post my measurements in the corresponding GitHub question as soon as I have some time.

[don alex]

@Ron said in Capacitive Soil Moisture Sensor:

@Puneit-Thukral Thanks. I am not quite sure, so correct me please if I am wrong, but I think I am already using the MiniCore bootloader with platformIO. Or do I need to configure to explicitly use the MiniCore bootloaders? Also I have set BOD to disabled as I read somewhere that no BOD can also save battery.

hi

I'm not sure, but I believe I'm already using the MiniCore bootloader with platformIO. Please tell me if I'm incorrect. Is it necessary to set the MiniCore bootloaders explicitly?