Product Description: USB to GSM Module SIM800C Development Board​​

​​1. Product Parameters ( )​​

Input Voltage: 4.5V-36V DC (Wide Voltage Compatibility)

Working Current: ≥1A (Peak 2A, Stable Power Supply Required)

Communication Band: GSM/GPRS Quad-Band (850/900/1800/1900MHz)

Data Transmission Rate: GPRS Class 10 (Downlink 85.6kbps, Uplink 42.8kbps)

Interface: TTL Serial Port (3.3V/5V Logic Level Compatible), USB Virtual Serial Port

Bluetooth: IEEE 802.15.1 (2.4GHz Band, High-Version Support)

Operating Temperature: -40℃ to +85℃ (Reliable)

Features: SMS/Voice Calls, GPRS Data Transmission, TTS Voice Synthesis (High-Version) .
​​2. Main Pin Functions ( )​​

​​VCC​​: DC Input Positive Pole (4.5V-36V). Connect to power supply positive with parallel 100μF electrolytic + 10μF ceramic capacitor for filtering. Wire diameter ≥22AWG, ripple

​​GND​​: Power Ground. Use star-point grounding and co-locate with load to reduce noise.

​​TXD​​: TTL Output to MCU's RXD. Impedance matching resistance ≤100Ω, trace length ≤5cm.

​​RXD​​: TTL Input from MCU's TXD. Requires 22Ω series current-limiting resistor.

​​VMCU​​: Logic Level Matching (3.3V/5V). Outputs 5V TTL when connected to 5V.

​​RST​​: Reset Pin (Active Low). Hold low >100ms for hardware reset. Default high if floating.

​​BLUE​​: Bluetooth Enable (High-Version Exclusive). Pull high to enable Bluetooth .

​​3. FAQ​​

​​Q1: Module fails to register network (AT+CREG? not returning 0,1)?​​

A1: ① SIM card improperly inserted or directional error (reinsert with metal contacts facing down) . ② Only supports 2G networks (replace with mobile carrier SIM).