Sleep mode

I’m currently working with a SL6087 module as a modem. I use a four lines serial communication trough the main UART. I need to get the module into sleep mode while I’m not using it in order to reduce consumption, I try to do so by using the +WBHV command, AT+WBHV=1,2 to get it into sleep mode and AT+WBHV=1,0 to put it back into active state, as recommended in the AT Commands Interface Guide for Firmware 7.45.1 (Section “SLEEP mode with GSM stack turned off”: To switch the embedded module to this mode, use “AT+WBHV=1,2” command. The embedded
module must be restarted in order to take the new behavior into account. To disable this mode, use “AT+WBHV=1,0” command and restart.)
I send the AT+WBHV=1,2 command, wait for the proper response , then restart and wait for the “ok” response. A minute later I send the AT+WBHV=1,0 command, but I don’t get any response from the module. Do I need to send anything extra to wake the UART up? Or do I have to change the state in any other of the control lines (RTS, DCD or RI) in order for the module to come back to Active state?
I havent been able to find any information regarding this command. Does anyone knows how to solve my problem?


As mentioned in

the embedded module has restricted access to peripheral interfaces, thereby UARTs, USB, SPIs, I2C, GPIOs, ADCs and Buzzer are not available.

Therefore, UART interface is off during this mode and you can use either one below to wake up the module:

  • external interruption
  • key press
  • alarm
  • OpenAT timer expiration

Still, in this mode, we need to enable DTR pin otherwise module will go to sleep again.

As you are using 4-wires UART, maybe better for you to use “ ACTIVE mode with GSM stack turned off” (AT+WBHV=1,1) such that UART interface and AT command is always available so you can use AT command anytime to enable/disable the mode.

Slightly higher power consumption but the main players, RF and GSM stack, is turned off.
Hope it helps.

It worked perfectly
Thank you vey much :slight_smile: