Pinout
SIM800L GSM module pinout
Pins
- NET — antenna: solder the helical antenna here, or use the u.FL socket beside it
- VCC (3.4–4.4V, ~4.0V ideal — NOT 5V, and the 2A transmit bursts need a fat capacitor or a LiPo)
- RST (active low)
- RXD (module input) / TXD (module output) — 2.8V logic, use a divider from a 5V MCU
- GND
- RING (pulses low on an incoming call or SMS), DTR (pull low to wake from sleep)
- MIC+ / MIC− and SPK+ / SPK− — the analog voice path for a microphone and an 8Ω speaker
Specifications
| Network | 2G only: GSM/GPRS quad-band 850/900/1800/1900 MHz |
|---|---|
| Supply voltage | 3.4–4.4 V (≈ 4.0 V ideal, not 5 V) |
| Peak current | Up to 2 A transmit bursts |
| Logic level | 2.8 V (divider needed from a 5 V MCU) |
| Interface | UART, AT commands (auto-baud) |
| Data | GPRS multi-slot class 12 |
| Functions | Voice, SMS, GPRS data |
| SIM | Micro-SIM |
| Antenna | Helical spring or u.FL |
| Network check | Make sure your carrier still runs 2G |
Notes
- Brownouts from a weak supply are the number-one "it keeps rebooting" cause.
- The NET LED blinks every second while searching, every 3 s once registered on the network.
