behnam9856
Member level 3
It works with 7805 but I offer LM2576-adj regulator which supports 3A output.
it's very good for GSM/GPS modules...
it's very good for GSM/GPS modules...
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You can and you must write, according to the datasheet. Read it.
I read it, when I talk about (RS232-TTL conversor) I am talking about the circuit with the MAX232... etc, etc.
If you can not offer a constructive answer, I think the best option is not say any.
I construct the circuit acording to your schematic (https://www.novinupload.com/uploads/13452712681.png). I am having the same problem. When I turn on Sim908, It just send IIII, and I do not receive any response to AT commands and I can not set the baudrate ofcourse.
Do any have any idea to solve this problem?
I construct the circuit acording to your schematic (https://www.novinupload.com/uploads/13452712681.png). I am having the same problem. When I turn on Sim908, It just send IIII, and I do not receive any response to AT commands and I can not set the baudrate ofcourse.
Do any have any idea to solve this problem?
Best regards,
vipintruder
Hi
Got the same problems here. IIII
Do you try to syncronise over the debug port or over normal Pins 66 - 72?
Do you use only txd and rxd ? Is dtr connected with ground?
My connection is established to my Provider. I can see it on the Leds.
But i can't get access over rs232.
Which kind of flowcontrol do you use ? (on debug port)
And strange is that i send an AT and he send me a AT back. Not a OK ???
Any hints?
Greets Troelli
Sorry for my bad english ^^
I solved my problem, the MAX232 was not ok. I changed the MAX232 and now SIM908 worked correctly (without read the datasheet... xD).
Seriously, I read the datasheet. The MAX232 circuit in (Kosh's... ;P) schematic work fine.
Thanks for all.
vipintruder
great...
If your are using Max232 and +5V, I strongly recommend to use Max3232 or level shifter circuit, otherwise the RX pin of your module will be damage after several use...
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Ok, thank you for this information. I will design my final circuit with it.
Regards
I send "AT" and I get "AT" back . If I send more like "AT+CMTE" i get "AT" back. Thats so strange ...if you send AT and you get AT in response ... try sending "abcd" if you get "abcd" in response then that means that your connection/circuit has a fault ...
Try this and let me know
Seems to be an Echo ... but it isn't. How should I turn it off If i haven't access to the Device via RS232?When u get what you sent,it means the echo is on! turn it off...