Interfacing Raspberry Pi 5G HAT with other controller

Hi Meera,

I've not used that particular Pi HAT, but I have used another WaveShare Pi HAT (for 4G/LTE), and the easiest way to interface was to use the on-board USB-UART. I too didn't use Pi. I see your board also has a USB connector, although it's weird that it is a USB Type-A connector. Mine had a micro USB connector.

Waveshare has put the USB connector specifically for testing out using the UART, so if that doesn't work, then that needs to be resolved first. 

For the HAT board I used, I could see in Windows a "SimTech" device appear under Other Devices, and I could connect to it from a serial terminal (PuTTY etc). Then you can use the command manual to see what AT commands are available.

Thanks for the info shabaz . To use the on-board USB-UART, i can connect the USB UART to the microcontroller, right? Is there a specific model of USB-UART. For now i am using this model

https://my.cytron.io/p-uc00a-ftdi-usb-to-uart-converter?gad_source=1&gclid=CjwKCAjwx-CyBhAqEiwAeOcTdRxSOY-CX4LD6aRlMMRgviPsTpmzslS7RD6DMOrFXi9oXp66woBFOBoC4xAQAvD_BwE

And i am using the code below for the handshake

// Need this for the lower level access to set them up.
#include <HardwareSerial.h>

//Define two Serial devices mapped to the two internal UARTs
HardwareSerial MySerial0(0);

void setup()
{
    // For the USB, just use Serial as normal:
    Serial.begin(115200);

    // Configure MySerial0 on pins TX=D6 and RX=D7 (-1, -1 means use the default)
    MySerial0.begin(115200, SERIAL_8N1, -1, -1);
   // MySerial0.print("MySerial0");
//while(!Serial);
    Serial.println("Initializing 5G module...");
     Serial.println("Sending AT command...");
    MySerial0.write("AT\r");  
// Send AT command to check communication
    delay(1000);

     // Check response from 5G module
    while (MySerial0.available()) {
        char c = MySerial0.read();
        Serial.print(c);


}

But somehow i am not getting any response from the 5G module. Below is the current setup.

The XIAO USB is connected to the PC. The RX and TX pin of the XIAO is connected to USB to UART converter. And the USB port on the UART is connected to the 5G module.

1. Verify the data coming from ESP32 by connecting ESP32 Tx pin to Rx Pin of a TTL and use a putty/hterm to view the data from ESP32.

2. As a next step, connect the Rx/Tx pins of TTL to 5G board, send the "AT\r\n" at different baud rates. My board has a default baudrate of 115200 and check for "OK" response.

Once you verify these steps connect directly and run the code.

Don't use Arduino IDE serial monitor. It'll abstract the "\r \n " characters. You need to use hterm which can show each and every byte that's being transmitted and received.

I have tried to change the serial mapping. But it was unsuccessful.

balajivan1995 , i connected the ESP32 with the TTL and can view the data that i am sending from from the ESP32. As shown in the image below

i used the hterm and i get this result

Does this looks good?

There is a garbage character that appears before  or after "AT\r\n", enable the checkbox of hex along with Ascii to see the unnecessary character and remove it from the code. Try to find out the reason for that, now connect the ttl to 5g modem and send the message like this. Make sure the "CR-LF" is selected under "Send on enter" dropdown option. It will automatically add "\r\n". If the modem returns OK, then you can connect ESP32 directly to Modem.

Hi. I would like to update the progress. I have tried what you suggested balajivan1995 . But it was not a success either. I tried checking the design file, and I found that there is no UART pin available. The only available interface is the USB and PCIe.

Could it be the reason why I am not able to communicate through the UART? If so, what would be the best way to communicate the 5G modulewith the controller?

Appreciate your help on this matter, shabaz  and balajivan1995 . Thank you.

I don't have any experience in PCIe communication. As for the USB, we can try two things,

1. Connect USB to UART TTL to the board and connect it to ESP32's UART and hope AT Port is accessible through it.

2. Change ESP32C3 to ESP32S3 or some other controller that supports USB host communication. 

In this section, they've mentioned UART port is accessible in 3 modules, are you sure yours is not one of them? 

Yes balajivan1995 . I using the RM502Q-AE.

I will change the controller board and try to see if it can work.

Thank you.

It may be worth first confirming operation with a Pi. According to the Waveshare website, the UART is the only interface connected to the Pi. 

If the interface really is only USB and PCIe, then there's little hope of working with ESP32. 

There is a chance that USB may work, but only if ESP32 can operate as USB Host (which I have no idea if it can, but hopefully it is documented somewhere), if the interface on the Waveshare card is USB peripheral.

It may be worth first confirming operation with a Pi. According to the Waveshare website, the UART is the only interface connected to the Pi. 

If the interface really is only USB and PCIe, then there's little hope of working with ESP32. 

There is a chance that USB may work, but only if ESP32 can operate as USB Host (which I have no idea if it can, but hopefully it is documented somewhere), if the interface on the Waveshare card is USB peripheral.

Sorry for the late reply. Currently, I am confirming with Raspberry Pi.