[SOLVED] sim900a cancelling/remove from the sleep mode

[Raady Here]

I am using a sim900a module kit and connected through serial port, and sending commands through hyperterminal.

how to wake back my sim900a from sleep mode ?

to test send to sleep mode i have sent a command "AT+CSCLK = 1"
after that it doesnt respond to any command but some alarm sound started to beep.

to deactivate the sleep mode i have sent "AT+CSCLK = 0" even it doesnt respond to it.
even it doesnt respond to "AT"

when powering on it show sim ready, call ready
+CFUN:1
+CPIN:READY
Call Ready

when i make a call it shows
RING
RING
RING
and when sent an sms it receives
+CMTI: "SM", 21
when i trying to read AT+CMGR =21 and it doesnt respond again.

how to reset

- - - Updated - - -

in manual it written , pull down the DTR for 50ms, even it didnt make any difference !

 

[embRTS]

Try this
AT+CSCLK=2
the module decides by it self when it enters SLEEP Mode and if there is no data present it enters in SLEEP mode, Otherwise it will quit Sleep Mode

May be this would work and also please tell what is your project info ?

 

[Raady Here]

right now for testing purpose i have been sending various commands through the hyperterminal,
i hadnt worked any thing regarding my project module where in I have to get connected to a server 1. sent GPS data, 2. when server sends the mobile number i have to update by sending an SMS to that particular number.
for that purpose i am testing commands w.r.t read/send sms.

even I have tried sending AT+CSCLK = 2 sorry for mentioning about it.
there is no response for any thing.
tried different commands at first and it was responding fine. after I have sent AT+CSCLK=1, no response to any command.
tried hard reset by making DTR pin low for 50ms.
by default i see 3.7v on DTR pin.

- - - Updated - - -

I have sent command keeping DTR pin low and with out removing, sent AT+CSCLK = 0 and it solved.
previuosly i made it low and though it would it reset so removed the ground and used to send command.
I have miss read the statement " when DTR is grounded it activates serial port for 50ms " . I am sending a commands after removing the grounding where 50 ms will be over by then.
thanks.
AT+CSCLK = 2 is also being accepted now.