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Pinout of the J2 serial port
Pin 13.3V (pin 1 has a white stripe next to it)
Pin 2RXD (from serial terminal program to NSLU2)
Pin 3TXD (from NSLU2 to serial terminal program)
Pin 4GND

Attach:NSLU2-board-front-serial.jpg Δ

Pin 1 is the left-hand pin and marked on the NSLU2 PCB.

NB: In the photo above, a set of header pins has been attached to J2. As sold, J2 consists only of a series of solder filled holes in the PCB. If you wish to put a header on then you must remove the solder first.

By default, both RedBoot and the Linux kernel use 115200,8,N,1 settings.

See HowTo.AddASerialPort for details on adding a serial converter to allow usage of the serial port.


There is a second serial port on the NSLU2 but only receive and CTS are connected. It is not possible to connect to the transmit line. The connection points are on the back of the NSLU2 PCB.

NOTE: If a longer open-ended cable is connected to RxD? your NSLU maybe won't boot! Check, that RxD? gets a proper signal at least at boot-time (every time, for example, a gps-receiver isn't connected to the soldered-on RxD2?-cable, it hangs somewhere during redboot-init. This was at least observed with two different NSLU2 boxes).

Location of the second receive only serial port
RXDRight side of R128. The resistor itself may not be present, but the pad is available to solder onto.
CTSLeft side of R142

A useful connection (eg, for data logging) using just RXD above and a suitable ground. I soldered wires to R128 and the shield of the existing ethernet port, and am now satisfactorily receiving data from my electricity-usage monitoring device. [http://groups.yahoo.com/group/nslu2-linux/message/488]

view · edit · print · history · Last edited by Pete.
Based on work by johnnywhoo_DeleteThis_AT_gmx_net, tman, kivper, Pete Verdon, IN, and ka6sox.
Originally by ka6sox.
Page last modified on May 24, 2008, at 10:24 AM