Unable to communicate SIM808 Module using PL2303 usb to serial converter

[PRABAKARDEVA]

Hi All,

I have tried to communicate the SIM808 module using PL2303 but not able to see the status(RDY) of SIM808 module through PL2303 in PUTTY terminal.

SIM card is inserted and SIM808 module powered by 12v Adapter.

PL2303 module tested by loop back method and it is working fine. Connected the SIM808 module with PL2303 by TX(SIM808) -> RX(PL2303) then Pressed the PWRKEY button to power ON the SIM808 module and Module powered on STATUS LED goes high and Network LED also blink for every 1 second(Means network found).

But found some issue and need clarify on this.
1.Not able to see the status(RDY) of SIM808 module through PL2303 module.
2. When Ground(PL2303) connected to SIM808 moddule (Ground) received the status as OVERVOLTAGE POWERDOWN.Not able to find why this triggered when GRND pin connected each other.


Note: When checked the scenario(Status of SIM808 Module) through Arduino not able to found the issue 2(Means received the SIM808 Module status as RDY) without GND(Arduion) pin connected to SIM808 Module(GND).

 

[paulfjujo]

hello,

is your PL2303 cable TTL levels
or Low TTL (3.3v)

gnd black wire is linked to the case of USB connector ...and ground of PC computer ...
could somtime cause problems.


is it a 4 wires or 6 wires (with CTS/RTS) ?

 

[PRABAKARDEVA]

Thanks for the reply

hello,

is your PL2303 cable TTL levels
or Low TTL (3.3v)

PL2303 is TTL level

gnd black wire is linked to the case of USB connector ...and ground of PC computer ...
could somtime cause problems.

is it a 4 wires or 6 wires (with CTS/RTS) ?

It is 5 wires no CTS and RTS.

GND,RX,TX,3.3V and 5V.

It seems that Serial Port(TX,RX) of SIM808 Modlue is 3.3v characteristics.

I suspect that due to this the issue occurred.FYI., Image has attached.

 

[speedEC]

2. When Ground(PL2303) connected to SIM808 moddule (Ground) received the status as OVERVOLTAGE POWERDOWN.Not able to find why this triggered when GRND pin connected each other.

You have to resolve this harware issue first to see the result SIM module on terminal. Test the harware connection and see tha Voltages of PL2303, MCU.

I have tried to communicate the SIM808 module using PL2303 but not able to see the status(RDY) of SIM808 module through PL2303 in PUTTY terminal.

IN SIM300 DATASHEET:
The AT command set implemented by SIM300 is a combination of GSM07.05, GSM07.07 and ITU-T recommendation V.25ter and the AT commands developed by SIMCOM.
Note: Only enter AT command through serial port after SIM300 is power on and Unsolicited Result Code “RDY” is received from serial port. And if unsolicited result code”SCKS: 0” returned it indicates SIM card isn’t present. If autobauding is enabled, the Unsolicited Result Codes “RDY” and so on are not indicated when you start up the ME
So, you have to set Baud Rate in SIM Module, after successully initialized. i.e. (After hardware issue solved), The terminal will be blank. You have to type AT at Terminal. If you receive OK, then start setting others, like AT+CFUN, Baud Rate, etc. Restart the SIM, will show, RDY and other initialized settings on Terminal.
If you need AT commands (SIM300), let me know. Will send. Hope all AT Commands more or less same for basic functions.
pmk

- - - Updated - - -

ADDED:

Note: When checked the scenario(Status of SIM808 Module) through Arduino not able to found the issue 2(Means received the SIM808 Module status as RDY) without GND(Arduion) pin connected to SIM808 Module(GND).

Without connecting any two device's GNDs, they can't talk each other.

- - - Updated - - -

Added:

I suspect that due to this the issue occurred.FYI., Image has attached.

If you suspect this, try to use one diode between TX (PL2303) and RX (SIM Module's) Pins. (Diode Dir -> TX to RX)

 

[vishnuk]

Hi,

The PL2303 can also work in 3.3V TTL level. Cut the 5V connection and connect it to 3.3V level using jumper in PL2303.
Once again verify the baud-rates.. I think the SIM800 doesn't need power from PL2303 (Need to verify that)

 

[paulfjujo]

hello,


check inside USB converter, quality of soldering .. poor quality on devices made in RPC ..
i loose many hours **broken link removed** ( see picture) before to discover the failure.

check also, continuity link on 0V , the black wire ...