Making a phone call from GSM module using SK-S7G2

Hi everyone,


So recently I've been working in a project with sk-s7g2 and gsm a7 module but I'm having problems doing that. I am using two UART frameworks one for transmit and the other one for receive SCI3 respectively SCI8. But the thing is I am not receiving any data in board from GSM module when I send AT commands, when I connect tx from transmit framework and rx from receive framework in board works perfectly. I don't know whats the problem, should I connect the gsm module with pmodb connector since the gsm supports 3.3v and 4.2v logical level.
Can you help me with this because I am having a lot of troubles?


Thank you in advance!

  • Hi Rigon96-
    Can you show us what signal connections you are using currently?

    Warren
  • In reply to WarrenM:

    Hi Warren,
    I have connected pin105(TX) from Uart TX framework with RX pin from GSM and pin706(RX) from Uart RX framework with TX pin from GSM module.

    Rigon
  • In reply to Rigon96:

    Hi Rigon96-
    Is there a Reset signal for the module? Maybe you can point me to the spec for the module you are using...

    Warren
  • In reply to WarrenM:

    Hi Warren,
    Yes there is a Reset pin in module but I didn't connect reset pin, the module that I am using is GSM GPRS GPS A7.
    Can that be the reason that I am not receiving data?

    Rigon
  • In reply to Rigon96:

    Hi Rigon-
    I would suggest you try connecting reset and also verify power and ground are applied robustly.

    Reset the module prior to initially sending commands- make sure you wait the amount of time the module spec calls for and make sure the Reset signal satisfies any additional requirements of the module.

    Let us know what you find...
  • In reply to WarrenM:

    Hi Warren,
    No it didn't work unfortunately.
    I connected reset pin from module to an output pin that I set as n-channel open drain(I also tried as CMOS) but it didn't work. I am really thinking maybe it can be the power supply that I am using (5.7V 500mA) even tho the module powers up and also the status led on GSM. The module requires 5-9 V but I can not find what's the minimum current for the GSM to work properly. Is 500 mA enough?

    Rigon
  • In reply to WarrenM:

    Hello Warren,
    Finally I am receiving data from the module. I changed the power supply because eventually the current(0.5 A) wasn't enough. For GSM module to work properly and to be able to transmit you need at least 2A. Also what I changed the SCI channels that I was using, it didn't work on SCI3 and SCI8 ( I don't know why) but when I switched to SCI0 and SCI4 I started to receive data.
    The thing now is, I am sending AT commands to module but I only got response to the first command so if I send AT I get OK which is good then when I send any other command I don't get any response.

    The code that I am using to read characters is this:

    void UART_FW_RX (void)

    {

    uint8_t rx_uart_data[64];

    while(1)
    {

    for(num=0; num<64; num++)
    {
    g_sf_comms1.p_api->read(g_sf_comms1.p_ctrl,&rx_uart_data[num], 1, TX_WAIT_FOREVER);



    #ifdef SEMI_HOSTING
    if (CoreDebug->DHCSR & CoreDebug_DHCSR_C_DEBUGEN_Msk)
    {

    printf("%c", rx_uart_data[num]);

    }
    if(rx_uart_data[num]=='\r')
    {
    num=0;

    }

    }
    #endif

    }