The Switch Simard Is a compact and integrated development board designed specifically to be used on products and save a lot of time handling GSM & GNSS power circuits and etc.
These pins are similar to the pins of the FPC connector. You can use them if you do not use the FPC connector.
P2‑2
VCC
VCC
–
P2‑3
RST
RST
–
P2‑4
CLK
CLK
–
P2‑5
DATA
DATA
–
P2‑6
Simcard-GND
SIMG
–
Pin map: left SEL header (GND/VCC/SEL/GND); right SIM I/F (VSIM, VCC, RST, CLK, DATA, SIM GND); FPC connector shown.
For switching between two SIM cards, you can connect the Select pin (pin header P3) to ground or VCC manually with a jumper, or you can control this pin using a microcontroller to set it high or low.
This is a dual SIM single-standby analog switch board (based on onsemi FSA2567/FSA2568) that allows you to connect two Mini-SIM (2FF) cards to a single cellular module and switch between them instantly.
How many SIM cards can be connected? +
Two full-size Mini-SIM (2FF) cards. Only one is active at a time (single standby).
How to switch between the two SIM cards? +
Control the SEL pin (P3-2):
• Low (0 V) → SIM 1 active
• High (VCC) → SIM 2 active
You can switch manually with a jumper or via any GPIO from your microcontroller.
What voltage should I supply to the board? +
Connect the same SIM voltage your module uses to VCC (P3-3): 1.65 V – 4.3 V (typically 1.8 V or 2.9 V). The board has built-in 5 A surge protection.
How to connect it to my GSM module? +
Two options:
• Use the 6-pin FPC connector (P1) with a 6-pin FPC cable
• Solder wires directly to the 6-pin header (P2): VSIM, VCC, RST, CLK, DATA, SIMG
Is the board breadboard compatible? +
Yes – 2.54 mm headers (P2 & P3) fit perfectly in any standard breadboard.
Does it support Nano-SIM (4FF)? +
No – only Mini-SIM (2FF) cards are supported natively. Use a 2FF-to-4FF adapter if needed.
What are the board dimensions? +
Compact size: 40 × 30 mm with mounting holes.
Is any level shifter or extra component needed? +
No – the board is a pure analog switch with no MCU or level translation. Just connect power, SEL, and SIM signals directly.
Can I switch SIM cards while the module is powered? +
Yes – hot-switching is supported. The module will detect the new SIM automatically after a few seconds