10 years, 5 months ago.

To Mihail Stoyanov

Hi Sir,

I am a student from Ngee Ann Polytechnic, Singapore. I am now currently doing my final year project. I have tried out the main.cpp that you wrote for Seeed_GPRS_Shield.

But I could not connect to network.

I printed the results out in the putty terminal and it printed as follow:

Could not connect to network. Retrying!

May I ask you a few things?

1. Is my connection right or wrong?

Mbed GPRS Shield

-VU to VIN

-GND to GND

-p9 to D0

-p10 to D1

2. May I kindly ask you that : Could I have a picture or a diagram of how you connect Mbed to Seeed GPRS Shield V2.0?

3. I put jumper caps to right since we use hardware serial port. Is it correct?(I inserted the images)

4. I do not insert the battery at the battery holder.

5.I used Starhub MaxMobile Prepaid Card. (https://www.starhub.com/business/support/internet-ip-solutions/faqs/prepaid-mobile-broadband.html)

I used main.cpp program the one that you wrote.

1. include "mbed.h"

1. include "GPRSInterface.h"

/ On many platforms USBTX/USBRX overlap with serial on D1/D0 pins and enabling the below will interrupt the communication.

• You can use an LCD display to print the values or store them on an SD card etc.

• /

Serial pc(USBTX, USBRX);

/**

• D1 - TX pin (RX on the WiFi side)

• D0 - RX pin (TX on the WiFi side)

• 115200 - Baud rate

• "apn" - APN name

• "username" - APN username

• "password" - APN passowrd

• /

GPRSInterface eth(D1, D0, 115200, "shppd", "NULL", "NULL");

int main()

{

wait(3);

Initialize the interface.

If no param is passed to init() then DHCP will be used on connect()

int s = eth.init();

if (s != NULL) {

printf(">>> Could not initialise. Halting!\n");

exit(0);

}

printf(">>> Get IP address...\n");

while (1) {

s = eth.connect(); Connect to network

if (s == false || s < 0) {

printf(">>> Could not connect to network. Retrying!\n");

wait(3);

} else {

break;

}

}

printf(">>> Got IP address: %s\n", eth.getIPAddress());

Prepare the http request to mbed.org

char http_cmd[] = "GET /media/uploads/mbed_official/hello.txt HTTP/1.0\n\n";

TCPSocketConnection sock;

sock.connect("mbed.org", 80);

sock.send_all(http_cmd, sizeof(http_cmd)-1);

printf(">>> Sent request to mbed.org\n");

Read the response

char buffer[300];

int ret;

while (true) {

ret = sock.receive(buffer, sizeof(buffer)-1);

if (ret <= 0)

break;

buffer[ret] = '\0';

printf(">>> Received %d chars from mbed.org:\n%s\n", ret, buffer);

}

sock.close();

Disconnect from network

eth.disconnect();

return 0;

}

May I kindly ask your help Sir?

I have sent you 4 pictures of the way i connect Mbed(NXP LPC1768) to Seeed Studio GPRS Shield v2.0 , the SIM Card that I use and the way I connect the jumper caps.

I am really looking forward to your reply Sir.

Thank you so much.

I really need your help.

Regards

Dorothy