Author Topic: Interface still consumes power in SLEEP_MODE_PWR_DOWN [Solved]  (Read 989 times)


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Issue is, even in SLEEP_MODE_PWR_DOWN the interface consumes energy - 3 mA.
Test case is as follows:
  • Bread Board Arduino
  • RF69 Module connected, SPI Interface
  • RF69 Module not used / initialized
  • Arduino in sleep
  • I monitor Arduino current
--->Looks OK, minimum of power consumption (Single digit ľA)
Let us modify 3 like this
    3. Initialize module (set TxPower(), set Retries(), etc.)
---> Arduino consumes 3 mA
I have had a look (Using oszillograph)  to the ports of the SPI Interface - There is no activity during sleep
Please keep in mind, the 3 mA are the consumption of Arduino only.
Consumption of RF69 modul is, initialized or not, still low.

Just being curious and even it is not the best idea to change port status of a ongoing connection, I applied a change to all pins (1..20) to OUTPUT, LOW just before going to sleep.
This helped a bit in terms of consumption and brought it down to ---> 1,5 mA

Any ideas, is going on? How to bring down the consumption of inactive SPI?


Seems it has been my own fault.
My voltage level shifter 5V -> 3,3V is just a simple voltage divider by some resistors.
I generally was aware of the impact(It is anyway not a final solution, just for breadboard use only), but was not aware of the low value resistors I soldered weeks ago to the module.
2 ports are at HIGH-Level (5V), the resistance is approx 3 kOhm each - matches more or less to the residual current.
Even the final confirmation is missing at the moment, I think that is the reason.   
« Last Edit: April 03, 2016, 06:29:47 AM by RTFM »