I want to interface gsm module sim 300 with p89v51rd2 . If i interface gsm with hyper terminal it working but i have problem with interfacing with microcontroller.
If i interface gsm with microcontroller so it is require max 232 ic? . It is already 1 max232 ic will be given on gsm module.
If your gsm module has a max232 IC, then you must use a max232 IC at your microcontroller side also. If there was no max232 IC then you could have connected it directly to the microcontroller.