SIM900 GSM Module working fine in terminal and not with PIC MCU

Hi,
I am using a SIM900 GSM module in USA. I have tested the modem with serial cable to computer and it is receiving messages and calls. here is the link for product. https://www.sainsmart.com/products/sim900-gprs-gsm-board-quad-band-module-kit-for-arduino.
i connected my circuit and the program is running with out any errors. but the message is not being received at TXD and RXD pins i believe. I am using it for a PIC16F877 micro controller. Please help me regarding this issue. Is the SIM900 modem comapatable with PIC MC. I connected TXD, RXD pins to Pin 25 and 26 of PIC16F877 micro controller.

There can be many issues associated with it.
You can observe the data capture on the TX and RX lines to see what the MCU is sending and what the module is sending to figure out the problem.
Make sure you add enough delay to allow GSM to boot up before you send any AT command.
The IO levels of UART should be 2.8V , match your MCU voltage levels to it or use level translators on TX and RX lines.

I got the output. Thanks for your help. I changed the voltage levels and also added delay according to your suggestions.

Glad to head that :slight_smile: