Hope RFM95/98 power usage in sleep mode?


I faced this kind of problem when played with ULPNode, In my case I was powering down RFM module with a mosfet to be sure 0 power will be consumed but had problem with port config pull up/down, I solved with the following code

The one part interesting for you is the part after f (!power)

/* ======================================================================
Function: powerRadio
Purpose : expose driver method of power or unpower the RF module 
Input   : true to power on false to power off
Output  : true if powered and module found
Comments: -
====================================================================== */
boolean ULPNode::powerRadio(uint8_t power)

  // do we need to power up the sensors
  if ( power) {
    uint8_t status_mask = 0;

    // From here and with latest Arduino version we have a problem
    // Arduino SPI library now check if SPI has already been initialized
    // if so, init is not done again and as we changed SS pin and some 
    // others to have full Low Power, we need to enhance back all as it
    // should be done in a real Spi init EACH time.
    //SPCR |= _BV(SPE);

    // Warning: if the SS pin ever becomes a LOW INPUT then SPI
    // automatically switches to Slave, so the data direction of
    // the SS pin MUST be kept as OUTPUT.

    // set back CSN pin with pullup (it was input)
    digitalWrite(RF_CSN_PIN, HIGH); 
    // now set it as output high
    pinMode(RF_CSN_PIN, OUTPUT); 
    digitalWrite(RF_CSN_PIN, HIGH); 

    // Power Up Modules SPI 

    // Enable back SPI and set as MASTER
    SPCR |= _BV(SPE);
    SPCR |= _BV(MSTR);

    // MISO pin automatically overrides to INPUT.
    // By doing this AFTER enabling SPI, we avoid accidentally
    // clocking in a single bit since the lines go directly
    // from "input" to SPI control.
    // http://code.google.com/p/arduino/issues/detail?id=888
    // Not needed because we didn't changed these pins 
    //pinMode(SCK, OUTPUT);
    //pinMode(MOSI, OUTPUT);

    // power ON VCC the radio module

    // RF module settle delay 
    sleepQuickWake( WDTO_15MS );

    if (_radio_type == RF_MOD_NRF24)
      status_mask = RF_NODE_STATE_NRF24;
    if (_radio_type == RF_MOD_RFM69)
      status_mask = RF_NODE_STATE_RFM69;

    // Init the radio driver with moteino config
    if (!driver.init()) {
      // Radio state not OK
      _status &= ~status_mask;
      return false;

    // Radio is okay
    _status |= status_mask;

    // Specific init for RFM69
    if ( _status & RF_NODE_STATE_RFM69) {
      RH_RF69 * prf69_drv = (RH_RF69 *) &driver;

      // Moteino settings
      // Copied from LowPowerLab 
      prf69_drv->spiWrite(RH_RF69_REG_29_RSSITHRESH, 220);

      // default moteino Frequency For 433 MHz 

    // Specific init for NRF24
    if ( _status & RF_NODE_STATE_NRF24) {
      // Defaults after init are 2.402 GHz (channel 2), 2Mbps, 0dBm
      //nrf24.setRF(RH_NRF24::DataRate2Mbps, RH_NRF24::TransmitPower0dBm))
  // So this is a power off
  if ( !power) {
    // This will configure the radio pins for correct low power mode

    // We're going to sleep, we've done our job no need to be awake by
    // RF module firing up a IRQ when we're in power down (can cause trouble?)

    // Once agin, very important even if we power off the module, because 
    // of pullup, module still powered via SS/IRQ Pin. if we don't do this
    // even if VDD of RFModule set to "float" using mosfet, current is get
    // drawn by other pins pullup (CS or IRQ), so disable pull up
    pinMode(RF_CSN_PIN, INPUT); 
    digitalWrite(RF_CSN_PIN, 0); 

    // Disable SPI device
    SPCR &= ~_BV(SPE);
    // unpower SPI of Arduino

    // unpower RF module

  return (true);

And for those interested here the code to disable all ATMega328 device for low power

Remember that I power down devices (I2C and SPI) using a mosfet to enable/disable them so all VDD pin of devices is then left float

/* ======================================================================
Function: disableCPUDevices
Purpose : disable Atmel integrated devices (for low power)
Input   : -
Output  : - 
Comments: - 
====================================================================== */
void ULPNode::disableCPUDevices(void)
  // Disable ADC 
  ADCSRA &= ~_BV(ADEN)  ; 

  // disable Analog comparator  
  ACSR |= _BV(ACD); 
  // Disable digital input buffers on all ADC0-ADC5 pins
  //DIDR0 = 0x3F;    

  // set I2C pin as input no pull up
  // this prevent current draw on I2C pins that
  // completly destroy our low power mode

  //Disable I2C interface so we can control the SDA and SCL pins directly
  TWCR &= ~(_BV(TWEN)); 

  // disable I2C module this allow us to control
  // SCA/SCL pins and reinitialize the I2C bus at wake up
  TWCR = 0;
  pinMode(SDA, INPUT);
  pinMode(SCL, INPUT);
  digitalWrite(SDA, LOW);
  digitalWrite(SCL, LOW);  



Even easier to minimize power use during sleep mode is to define unused IO pins as output (commonly used on ATmega/‘Arduino’).

23 posts were merged into an existing topic: Big STM32 boards topic

@BoRRoZ @everyone

I think the STM32 related posts should be placed in the Big STM32 boards topic
Maybe above STM32 posts can be moved to the STM32 topic (where they are easier to find and don’t hijack this topic).

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done… let’s keep this topic for the RFM95/98.

I stumbled across this conversation about enabeling the PA_BOOST to have +20dBm

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I tried to combine deepsleep of atmega328 and RFM95 controlled via LMIC library.

  • at first i do a JOIN to the LoraWAN nework and store the session information in RAM
  • after an initial data send i put the CPU to deepsleep via
    LowPower.powerDown(SLEEP_8S, ADC_OFF, BOD_OFF);
  • then i call
  • every nth wakeup i call
  • and recall the last session settings via
    LMIC_setSession (netid, devaddr, nwkKey, artKey);
  • additionally i set the same parameters as i did in EV_JOINED event
    LMIC_setClockError(MAX_CLOCK_ERROR * 1 / 100); //Relax RX timing window
    LMIC_setAdrMode(1); //enable ADR
    LMIC_setDrTxpow(DR_SF9, 15);
  • finally i trigger a new packet via

So far this seems to work well, but there is a question left: is the sequence
LMIC_setClockError(MAX_CLOCK_ERROR * 1 / 100); //Relax RX timing window
LMIC_setAdrMode(1); //enable ADR
LMIC_setDrTxpow(DR_SF9, 15);

to much, or do i need to set additional parameters?

The question might sound stupid because it seems to work fine, but i want to be on the safe side…

  • I never shutdown/reset LMIC while sleeping (or save anything from the session)…
  • LMIC_setDrTxpow(DR_SF9, 15): there is probably no point of setting Data Rate if you do ADR; also if you are in Europe, 14dBm is the maximum you can use (It is not important as LMIC doesn’t do anything with that anyway)

So, have you measured your power consumption with/without shutdown?
If I have not done a mistake there was a significant difference!

I have not, less than 0.7 µA was good enough for me…


I’m now using the MSP430 and RFM95. When I was testing the total current of the whole system. I put RFM95 into sleep and put MSP430 pin’s output low. The system cost 0.5mA which is much high. What I’m sure of is that MSP430 cost only a few uA. I also guess the DIO cost some power. But I didn’t find anything in the datasheet to configure the DIO.
If anyone can help, that will be so grateful.

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Hey i am currently trying to use msp430 and rfm98 for data transmission and i am kinda stuck so can you please help me by sending your code and the library you are using for rfm98 module