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Viewing 15 posts - 16 through 30 (of 196 total)
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  • in reply to: BOD_OFF powerDown() #16227
    LIM PHANG MOH
    Keymaster

    It can’t be enabled or disable through software in power down on ATMega1284P (look at table 8.1 under section 8.2 Sleep Modes). So, it must be disabled by fuse setting.

    in reply to: SX1262 LoRa chip #16147
    LIM PHANG MOH
    Keymaster

    Not at the moment, there are some pin differences involved. We have concentrating on LoRaWAN lately.

    in reply to: Using the RST pin #16146
    LIM PHANG MOH
    Keymaster

    That is reset the MCU. It has an external pull-up that keep it at 3.3V.

    LIM PHANG MOH
    Keymaster

    The simplest form and basic example on the PID library would work.

    LIM PHANG MOH
    Keymaster

    I think the issue is related to this. Please use v1.1.1 of the PID library.

    LIM PHANG MOH
    Keymaster

    Please select Arduino Pro Mini with ATmega328P 3.3V 8MHz as the board.

    in reply to: 6.4V Lithium iron phosphate battery #15887
    LIM PHANG MOH
    Keymaster

    They are the same both JST and the VBAT pin. The board supports Li-Ion/Pol although it can be used with the LiFePO4 with care (no charging through USB or VIN allowed as the charge voltage is different compared to Li-Ion/Pol). All boards are tested to draw below 20 uA during sleep in our test, anything above that goes to the reject bin.

    in reply to: Using MOSFET for power saving #15869
    LIM PHANG MOH
    Keymaster

    If you are driving something, put it according to it’s appropriate state. Input pull is used when a pin is not connected to anything.

    in reply to: Using MOSFET for power saving #15792
    LIM PHANG MOH
    Keymaster

    I am facing the same problem. Using atlas scientific pH sensor that consumes 1mA when in sleep mode. The sensor is powered straight from mini ultra pro v3 with 3.3v. Also using i2c protocol to read data.

    It’s going to be a problem if you directly use a MOSFET only to control the power. As there’s another I2C device on the bus (EUI-64 chip), when you cut off the power, the SCL & SDA lines will go to ground. The SDA and SCL pins are pulled up to 3.3V. So, you will see a sink of current from 3.3V to ground through the pull-up resistor which means higher sleep current. What you probably need is a I2C bus switch like for example the TCA4311A from TI or anything similar.

    in reply to: Cannot measure power consumption on Mini Ultra Pro v3 #15785
    LIM PHANG MOH
    Keymaster

    If the voltage drop on the VUSB is too much, the board cannot be powered which depending on your multimeter burden voltage. There’s also a diode that will drop around 0.3V-0.5V (depending on current) on the board.Measure the 3V3 and also VBUS, how much is the voltages there? VBUS should be 4.4V when used with valid VUSB or VIN.

    in reply to: Cannot measure power consumption on Mini Ultra Pro v3 #15783
    LIM PHANG MOH
    Keymaster

    The 5V is from the USB power, do not feed anything to that pin. Measuring current should be on the VBAT where the limit is 4.2V like a Li-Ion/Pol battery and please use a battery to do this else if you mistakenly apply power on USB or VIN, that might kill the PSU and also the board.

    LIM PHANG MOH
    Keymaster

    The RFM95 radio goes into idle mode by default in which the transmitter and receiver internal block is turned off. So, it is okay usually if the radio part not used at all. You can also make sure the CS pin (pin D5) of the radio is pulled high so it is deselected on the SPI bus.

    When using the radio, it’s best to have an antenna but based on my experience the RFM95W are pretty tough. But I just only killed 2 units of RN2483A radio when I was lazy plugging in the antenna.

    in reply to: Using MOSFET for power saving #15770
    LIM PHANG MOH
    Keymaster

    Any 100 nF would do. I went with it because it is common on all my circuits. Tried with smaller ones like 10 pF and 100 pF, makes not much different on turn on time. A pull-up resistor is usually employed so when not driven (during power up), the MOSFET is by default turned off. A current limiting resistor is needed as it work in pairs with the capacitor during turn on time.

    in reply to: Using MOSFET for power saving #15761
    LIM PHANG MOH
    Keymaster

    Hi Jatinder,

    It depends on how much current the sensor is sinking. I usually employ a P-MOSFET like DMP2035U-7 (our favorite) to do this. Any MOSFET will do, make sure it is a logic level MOSFET and the maximum VGS is within the limit of your switching. Just make sure you add a very small capacitor in in between the gate and drain to reduce and slow down the in-rush current when turning it on even though the load start-up current is little..

    in reply to: Flagging WDT vs INT1-pin WakeUp #15754
    LIM PHANG MOH
    Keymaster

    I think you would need to set an extra global variable/semaphore in the WDT ISR to check whether it is woken up by the WDT. This has to be added in the LowPower library file. On top of that, I would advise putting into SLEEP_FOREVER first and test the other 2 wake up source. Why? There’s a minimum pulse width that they need to meet in order for the ISR to take place. Else it would wake up but not knowing what woken it up as the pulse might have gone high before it check them.

Viewing 15 posts - 16 through 30 (of 196 total)