The SIM800C mainly controlled by AT commands, so just find a USB convert to TTL serial port module,and 5V,GND,TXD,RXD pins connect to VCC_IN, GND,RXD, TXD pins of SIM800C

When the module is started, the indicator LED flashes once every 1 seconds, and after a period of time, the indicator LED flashes once every 3 seconds, it means the SIM800C start works normally.

Features:

1. Input voltage range 5V-18V DC;
2. Self-propelled SIM card slot design, support 2G / 3G / 4G card
3. Module will connected to the network automatically after you power on it
4. Compatible with a variety of single-chip serial ports
5. Reserved headset and microphone interface
6. Support TTS DTMF function
7. Bluetooth 3.0 protocol, enhanced Bluetooth antenna, support for serial port SPP and audio services
8. Reserved lithium battery-powered BAT interface, you can use 3.7V lithium battery or 18650 lithium battery
9. Reserved IPEX interface, SMA interface, spring antenna interface, can be used on different occasions
10. With work indicator: the LED will flash 1 time per second when no network, no SIM card or SIM card inserted, and will flash 1 time per 3 seconds under normal conditions
11. Board size: 40.9*51.3mm

Specifications:

• GND: Power ground
• VCC_IN: Power supply pin, input DC5V-20V
• RI: Ring indicator
• DTR: Data terminal preparation
• TXD: TTL serial port transmission
• RXD: TTL serial port receive
• U2_R: module serial port 2 receive
• U2_T: module serial port 2 send transmission
• V_M: connect to the core voltage (5V/3.3V,it depend on your MCU) of MCU for level match(generally, NC also be OK for this pin)
• ADC: ADC detection
• SPP: Audio output positive
• SPN: Audio output negative
• MC-: Audio input negative
• MC +: Audio input positive
• PWR: Power enable or disable(enable when low level)
• BAT: lithium battery input pin, 3.3v-4.4v