UART communication with HAT

Hi All,

We are using the 3G/4G&LTE HAT with EC25-E module on a custom SOC board. Our SoC is Xilinx zynq 7030, which is a dual-core ARM Cortex-A9 based system. We have connected our UART and the other GPIOs to the 40-pin header and trying to send AT commands through that UART. But there is no response from the HAT, for the AT command sent.

We have sent the Hat Power Off, W_Disable and DTR signals to Low, before sending the AT command. The UART baud rate is set to 115200, and the UART Jumpers on the HAT are shorted as per the instructions given in documentation.

We have given supply to both 3.3V and 5V pins on the 40-pin header with respective voltages. Does it cause any issue?

Does anybody have any clue why it is not working? Please point out any of the missing things.


What is the voltage level of the UART pin on your SoC?
It should be 3.3V, since the UART of the mini PCIe module is 3.3V