The A7670 Evaluation Board is a compact and practical evaluation platform designed for the Simcom A7670 4G LTE module. It provides all the essential interfaces and connectivity options you need to quickly bring your IoT, M2M, or 4G-based projects to life. With built-in Bluetooth & Wi-Fi antennas, GNSS and GSM connectors, audio interfaces, and user-friendly pin headers, the board simplifies development and reduces hardware setup time. Whether you’re testing, prototyping, or integrating into a larger system, the A7670 Eval Board makes development faster, easier, and more reliable.
The detailed assignment of the peripheral interfaces on the evaluation board is as follows:
NO.
Name
1
USB Type-C
2
Simcard Socket
3
Microphone and Speaker output
4
Bluetooth and Wi-Fi antenna
5
Level shifter chips
6
Watchdog timed disable
7
GSM UFL Antenna
8
User button
9
LEDs
10
Watchdog unit
11
3A Buck
12
GNSS UFL Socket
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Tip
When the Open-CPU feature is not in use, always keep the WDT Disable jumper in place. This prevents unwanted resets triggered by the watchdog timer circuitry.
The board uses the Simcom A7670E (or A7670C/A7670G depending on variant) — a compact LTE Cat 1 module with 10 Mbps DL / 5 Mbps UL, fully certified for Europe, Asia, and global use.
Does the board support Open-CPU / AT firmware development? +
Yes — the A7670 series supports Simcom Open-CPU SDK (C programming on module). The board includes a watchdog disable jumper specifically for Open-CPU development to prevent unwanted resets.
Can I connect normal SIM cards? +
Yes — standard nano-SIM (4FF) socket with SIM detection and full power control.
Is Bluetooth and Wi-Fi available? +
Yes — the A7670E supports Bluetooth 5.0 and Wi-Fi 802.11b/g/n. On-board PCB antenna + optional U.FL connector pads for external antennas.
Is GNSS (GPS/GLONASS/BeiDou/Galileo) supported? +
Yes — integrated multi-constellation GNSS with active/passive antenna support via dedicated U.FL connector and 1PPS output on header.
What voltage levels are on the headers? +
All I/O pins are 3.3 V tolerant thanks to onboard bidirectional level shifters. Safe to connect directly to Arduino, ESP32, Raspberry Pi, STM32, etc.
How do I power the board? +
Via USB-C (5 V) → onboard high-efficiency 3 A buck converter generates clean 4.2 V for the module. You can also feed 3.8–4.4 V directly to VBAT pins if needed.
How do I access the debug / AT command port? +
Two ways:
• USB-C automatically enumerates as multiple COM ports (AT, NMEA, Debug, Modem)
• Dedicated RXD_LOG / TXD_LOG pins on header (115200 baud) for low-level logs
Can I use the audio jack for voice calls? +
Yes — 3.5 mm TRRS jack with mic input and speaker output. Perfect for testing VoLTE or classic circuit-switched voice.
Is this board suitable for production? +
It is an evaluation / development board, but full schematics, layout (KiCad), and BOM are provided so you can easily copy the design into your own carrier board.
Do I need the WDT Disable jumper? +
Yes — when not using Open-CPU, keep the WDT Disable jumper installed. Remove it only during Open-CPU development to allow the external watchdog to reset the module if your code hangs.
