Features / Specs
- Dev Board Model: SIM900A MINI V3.8.3
- GSM Module: SIMCom SIM900A (Refurbished Module – Tested & Guaranteed to be working)
- Guaranteed Firmware Version: 1137B09SIM900B32_ST / 1137B15SIM900M64_ST
- Supply Voltage: 5VDC (Rated ≥ 1A) (1000uF Tantalum Capacitor on supply rail)
- Frequency Bands: Dual-Band (900/1800MHz)
- Transmitting Power: Class 4 (2W) – EGSM900 / Class 1 (1W) – DCS1800
- GPRS Connectivity: GPRS multi-slot class 10 (Default) / GPRS multi-slot class 8 (Optional)
- GPRS Data Transfer Speed (Max): Downlink (85.6kbps) / Uplink (42.8kbps)
- Compatible AT Command Sets: Not Specified
- Comms Interface: UART (1200bps to 115200bps) (3.3V and 5V Compatible)
- Firmware Upgrade: Supported via Debug UART interface
- SIM Card Slot: Standard SIM (Micro and Nano SIM cards will require an adapter)
- Antenna Connector: SMA Female
- Operating Current (Typical in Sleep Mode): 1.5mA
- Operating Temperature (Approx): -30℃ to +85℃
- Indication LEDs: 2x Red LEDs connected to the “NETLIGHT” and “RI” pins
- Features MAX232 with protection circuitry for RS-232 communication
- Header Pin Pitch: 2.54mm
- Dimensions: ~(55.8mm x 48.6mm x 13.6mm)
Note on Refurbished Modules:As you may have noticed, the SIMCom modules used on these breakout boards are classified as refurbished. What this ultimately means is that the modules have been de-soldered from another device that may or may not have been in operation, and re-soldered onto the brand new breakout boards with the rest of the components being brand new as well. The modules are still fully operational and original SIMCom modules, but may have some marks and scratches on their labels (This happens during de-soldering). Any similar SIMCom module sold at this price point will almost always be using a refurbished module. Some manufacturers have even gone to the lengths of reprinting the module label so that they seem new, but if you look closely you should be able to see the original label underneath. We would like to be completely transparent regarding all the items we sell which is why we think it is important that we explain the above in such detail.
That being said, every SIMCom board we sell has undergone some basic quality control before we make them available to our customers. This includes a visual inspection, firmware re-flash to the above mentioned version, and a simple network registration check.
Pin Description
- 3VR-> UART RX Pin (Connect to Microcontroller TX) – Connected directly to SIM900A
- 3VT-> UART TX Pin (Connect to Microcontroller RX) – Connected directly to SIM900A
- 5VR-> UART RX Pin (Connect to Microcontroller TX) – Connected through level shifter to SIM900A
- 5VT-> UART TX Pin (Connect to Microcontroller RX) – Connected through level shifter to SIM900A
- GND-> Ground
- VCC_mcu-> TTL Logic Level Supply (Level for UART communication)
- GND-> Ground
- VCC5-> SIM900A Supply Voltage (5VDC – Rated ≥ 1A)
- RST-> Connected to “NRESET” pin
- RESTART-> Connected to base of NPN transistor which is connected to “PWRKEY” pin
- ring-> Connected to “RI” pin
- status-> Connected to “NETLIGHT” pin
- DB9-2-> Connects to SIM900A “TXD” pin through MAX232 chip
- DB9-3-> Connects to SIM900A “RXD” pin through MAX232 chip
- GND-> Ground
