Hello everybody, I am new to this topic so need help. I am trying to build my end node using STM32L151CBU6 and SX1272. When i disconnect the resistor which supplies power to sx1272 i am able to get 1.8uA of current consumption by putting the STM IC in standby mode. But if the resistor is connected …

according to sx1272’s datasheet it should draw around 1uA of current in sleep mode. Is there any way that i can configure the io’s of sx1272. I might be wrong but i guess they remain in floating state that’s why it is drawing this much current

so the only thing the MCU does is setting the sx1272 to sleep and then itself ? if that’s the case I connect a multimeter between the power line and start fiddling with the different sleepmodes and instructions to the sx1272 and see what’s happening to the current draw. or is there something still …

I am not sending any data packet. I tried connecting the CRO to check the output at various pins. The HSE oscillator and the sx1272 oscillator are not working so is it fair to assume that both the IC’s are in sleep mode? The RTC oscillator of 32khz is working fine but i guess that consumes around …

The current drawn by sx1272 in standby mode is 1.5mA. As i am getting the current in the range of 70uA so i guess both my IC’s are in sleep mode. Is the order in which i am turning them off wrong?

Any floating input pins? Used a meter to see if any.

probably … I was thinking the same… or maybe you forgot one registerinstruction or something. I don’t know … have to look it up in the sheet myself :sunglasses: maybe you can extract some info from the semtech driver

I made all the pins as input and pull up to avoid any kind of floating pins on stm32. i am unable to modify the sx1272 pins except for DIO and spi

SX1272Reset(); GpioInit( &AntTx, RADIO_ANT_SWITCH_TX, PIN_INPUT, PIN_PUSH_PULL, PIN_PULL_DOWN, 0 ); GpioInit( &AntRx, RADIO_ANT_SWITCH_RX, PIN_INPUT, PIN_PUSH_PULL, PIN_PULL_DOWN, 0 ); // SX1272AntSwDeInit(); DelayMs(1); SX1272Write(REG_DIOMAPPING1, 0xFF); SX1272Write(REG_DIOMAPPING2, 0xF…

i checked the current consumption at the rf side. when the led is glowing after disabling the RF part i get around 8uA of current at the sx1272. but after stm32 goes into sleep mode the rf part starts consuming 70uA of current.

The nss pin becomes floating as soon as i put the stm32 ic in stop mode. This was the reason behind the current consumption. When i put it in stop-mode instead with low power regulator on i am able to reduce the current to 9.5uA. Can this be reduces further?

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Getting high current in low power mode

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kersing (Jac Kersing) August 23, 2017, 4:19pm 23

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