Question: how gsm module works with microcontroller?
Answer: GSM modem works with 12V DC and the microcontroller works with 5V. ... GSM modem is interfaced with 8051 microcontroller through MAX232 with the help of RS232 cable for serial communication. MAX232 device is used to convert TTL logic level to RS232 level during serial communication of microcontroller to the GSM modem.