T:Power Saving GL865

  • Q: Type of module? A: GL865-Dual
    Q: Firmware version? A: 10.00.155
    Q: Type of starter kit you have? none
    (S1, S1B, S2, S3, S4, EVK1, EVK2, none, other)

    I am trying to put GL865-Dual into power saving mode.

    Using RSTerm interactively, I enter AT+CFUN=4 and expect power consumption to reduce from 50mA to about 4mA. It reduces to 25mA only.

    I have tried putting DTR low after CFUN=4 but no change.
    I also tried MOD.powerSaving(20) in script but the result is the same.

    Where is the extra current going?
    Or what have I done incorrectly.

    My serial interface is using FTDI232RL Serial/USB between RSTerm and GL865. I have tried putting FTDI in reset when script executes MOD.powerSaving but it doesn't help. If anything, the current is more.

    Nothing else is connected the GL865.

  • I have not had any response to this post and wondered if there were any suggestions for me.

    I have disconnected all Tx, Rx, CTS, RTS lines from the module and use a port to signal low power mode (CFUN=4). I monitor the current and nothing happens - still ~50mA. Before I disconnected the serial lines I checked that CFUN=4 was successful so I am sure it is being processed but the power remains high.

    This is a big problem for my development and I would appreciate some advice what to check. AT-Configuration?? Hardware??

  • Dear DocP,

    please read carefully the GL865 HW User Guide rev.3

    At page 23
    AT+CFUN=1 21,0mA
    AT+CFUN=4 18,0mA
    AT+CFUN=0 or 5 1,5 to 3,9mA

    AT+CFUN=4 is not a power saving mode. It just disable the GSM radio (TX and RX). Serial port and microprocessor still works at the same power.

    AT+CFUN=0 or 5 reduces the clock of the microprocessor.

    Wait that the module is registered to the network before entering in power saving. The module doesn't enter in power saving mode if it still has to scan the network and perform the location update procedure.

  • Thank you.

    I have tried CFUN=4 followed by CFUN=0 and the power drain certainly reduces now to a few mA.

    However, I cannot see any evidence of Python running.
    I set a flag to toggle a LED ON/OFF in the main loop which works normally but when CFUN=0 is executed the LED stops. i.e. no code running.

    If I force RTS Hi the current returns to almost the original value but still no code is executing. PWRMON remains Hi.

    Clearly, I have missed something but your previous reply confirms that the code should remain active, and the AT_Command book states that RTS Hi restores full functionality.

    Why is the code not running as it is supposed to in this power save mode.

  • After some time on another project I have now returned to this topic.

    I have done some more 'experimenting' with GL865 and can put the device in low power mode (CFUN=5). I can also issue AT#SYSHALT and reduce current to <1mA.
    I have a very small code running as a 'bootloader' to speed up the startup. In normal use I can send AT#EXECSCR and the program starts running within a second. All this works fine and as expected.

    The problem I have is to wake the module from low power and run the code quickly. This is necessary because the module must capture an image from a serial camera immediately following a trigger. I have tried AT#RESET, DTR and even just power but there is always a long delay (~15secs) before startup and code execution.

    From the previous discussion my understanding is that the code is still running at reduced clock, so why can't I quickly jump back to the code from low power mode.

    Any advice appreciated.

  • We think it's not possible to have fast reaction time with Python script running. However when Python script is running the Power saving is not active.
    Maybe we could help to improve the reaction time if we give a look at the script, but we don't guarantee

  • Thank you. This explains why I have been unsuccessful in getting a fast boot time!

    Waiting 10 -15 secs after a stimulus is much too long, the event will have ended before action is taken. My solution will be to use an external MCU e.g. PIC to do the initial image capture, then pass transmission over to GL865.

    I don't understand why the internal processor cannot continue to run at micro-power with the modem off. It would simplify design enormously…..

    Thanks again for your help. I think we can close this thread now.

  • Quote

    I don't understand why the internal processor cannot continue to run at micro-power with the modem off

    The reason is the internal structure. I will close this thread now.