MOD-GSM Communication

[jakebar]

Hi,

I have UEXT board MOD-GSM , i'm trying to get to a point where i can send commands, I have tried to communicate with this board over serial with Arduino and with MOD-USB-RS232 with both when i press the power key i see some garbage ascii on realterm, now im not sure what causing this issue , im using power supply of 9V DC 500ma maybe it doesnt have enough power or has too much? I also red somewhere that it is by default set up to use hardware flow control (RTS, CTS) , currently im only using RX TX for communication do i need all pins for it to work, any help would be appreciated

[LubOlimex]

Hello jakebar,

If you receive some characters that look like garbage that usually means you have used bad baud rate. Did you use 115200?

If charging the board or you have the battery connected you will need to provide 500mA @ 12V as mentioned in the manual: https://www.olimex.com/Products/Modules/RF/MOD-GSM/resources/MOD-GSM.pdf.

Best regards,
Lub/OLIMEX

[jakebar]

Hi Lub,

I have tried to connect using 115200 and 9600 , both give garbage ASCII, i should mention that only when i press the pwrkey when its turned off i get a load of garbage ASCII (about 3 lines). when its turned on, and i call the SIM card from another phone it does not output any characters. i have the board without battery just 9V 500mA connected with all switches in the right place for setup without battery.

[LubOlimex]

Hey jakebar,

An additional thing:

1) Both boards are MODs - this means they are configured as devices (not host boards) - this matters when trying to communicate via the UART/RS232 on the UEXT. The thing is that if both UEXTs are configured the same RX will meet RX and TX will meet TX which would lead to collision. Please configure the jumpers on MOD-USB-RS232 as a host (for more info please check page 9 of the manual: https://www.olimex.com/Products/Modules/Interface/MOD-USB-RS232/resources/MOD-USB-RS232.pdf).

Best regards,
Lub/OLIMEX