In most phones, pin 4 (ID) is used to detect if a USB OTG cable is attached. In the Nokia 105 RM-908, pin 4 serves a different purpose: . 3. Exact Nokia 105 RM-908 USB Pinout After analyzing the motherboard schematics (available from service manuals) and practical reverse-engineering by repair communities, here is the verified pinout for the Nokia 105 RM-908 micro-USB port.
The Nokia 105 (model number RM-908 ) is legendary for its durability, month-long battery life, and ultra-simple functionality. As a classic feature phone, it lacks the complex data-transfer protocols of modern smartphones. However, when the charging port breaks, the phone refuses to power on, or you need to extract critical contacts, understanding the Nokia 105 RM-908 USB pinout becomes essential.
Power the phone from its own battery. Use a terminal program (115200 baud, 8N1). At power-on, you’ll see diagnostic output. Using proprietary AT commands, you can dump phonebook via AT+CPBR=? . Q: Can I charge my Nokia 105 RM-908 with any micro-USB cable? A: No. Most modern cables leave pin 4 floating. You need a cable with pin 4 tied to ground, or use the original Nokia charger (which internally shorts ID to GND). Q: Why does my PC recognize a “Nokia USB Device” sometimes? A: If you short D+ and D- together or apply 5V to them, the phone can enter “test mode” – but no user data is accessible. It’s a diagnostic state only. Q: Is the pinout the same for Nokia 105 DS (RM-908 dual-SIM)? A: Yes, identical. The dual-SIM variant uses the same PCB layout and USB pinout. Q: I soldered a new port, still no charge. What next? A: Check the 10kΩ resistor between pin 4 (ID) and ground. It may be damaged. Also verify the charging IC (usually a small 6-pin IC near the USB port) is getting VBUS. 9. Conclusion The Nokia 105 RM-908 USB pinout is simple but non-standard. Its reliance on pin 4 (ID) for charging detection and the absence of functional data lines on D+/D- make it unique among micro-USB devices. By understanding that pin 4 must be grounded, and that pins 2/3 are only for factory flashing, you can repair, modify, and even recover data from this rugged feature phone.
| Phone test point | USB-TTL Adapter | |-----------------|-----------------| | TP-51 (RX) | TX (3.3V) | | TP-52 (TX) | RX (3.3V) | | GND (any ground) | GND |
| Pin | Name | Function | |-----|------|-----------| | 1 | VBUS | +5V (Charging power) | | 2 | D- | Data line negative (USB 2.0) | | 3 | D+ | Data line positive (USB 2.0) | | 4 | ID | Identification / On-The-Go (OTG) | | 5 | GND | Ground (0V) |
| USB-A Pin | Micro-USB Pin | Wire color (typical) | |-----------|---------------|----------------------| | VBUS (+5V) | Pin 1 (VBUS) | Red | | GND | Pin 5 (GND) | Black or bare | | No wire | Pin 2 (D-) | Leave unconnected | | No wire | Pin 3 (D+) | Leave unconnected | | GND (shorted) | Pin 4 (ID) | Connect to GND inside the micro-USB plug. | Solder a jumper wire from Pin 4 (ID) to Pin 5 (GND) inside the micro-USB connector housing. This pulls ID low, signaling the phone to accept charging. Without this connection, the Nokia 105 RM-908 will not charge from many power sources. B. Factory Flash / Data Cable Wiring To enter flashing mode (using Nokia’s proprietary tools like Phoenix Service Software or ATF Box), both D- and D+ need specific connections, usually via a USB-to-serial converter or a "USB to UART" adapter.
The key to unlocking repair and diagnostic functions lies in understanding the of that micro-USB port. 2. The Standard Micro-USB Pinout (For Reference) To understand the RM-908, we must start with the standard micro-USB specification. A typical micro-USB connector has 5 pins: