At the back of the Ben NanoNote, there are GND, TXD, and RXD pins, which you can use for a serial console to the device.
To get output from those pins you need a TTL <-> RS232 converter (such as the FTDI TTL-232R-3V3 USB-to-TTL cable) which This version of FTDI's USB to TTL serial adapter cables has it's I/O pins configured to operate at 3.3V levels. This means also that the Ben NanoNote serial console works at typical 3.3V level. So DO NOT use a 5.0V levels converter.
Serial console connected to an FTDI TTL-232R-3V3 USB-to-TTL cable.
Serial console detached, the tiny wires easily fit under the battery so you can use the NanoNote as usual.
See also here.
If you want to know that how to soldering these test points, you can also see here.
- Connect GND on the NanoNote to GND on your TTL-to-RS232 converter.
- Connect TXD on the NanoNote to RXD on your TTL-to-RS232 converter.
- Connect RXD on the NanoNote to TXD on your TTL-to-RS232 converter.
- The default Baud rate is 57600, 8n1, no hardware or software flow control.
- You can use any terminal program on the PC side, such as minicom. You can use minicom with the following sample config file:
$ cat /etc/minicom/minirc.qi
pu port /dev/ttyUSB0
pu baudrate 57600
pu rtscts No
$ minicom -o qi
 The RXD wire
The RX serial data channel can be set in the CPU to GPIO mode or to alternative function (serial RX). By
default, it's set to GPIO, as a keyboard line uses this (pin 26 of GPIO port D)
To enable the alternative function (RX), and disable the keyboard use, we have to write '1'
to the proper position (so, the 32-bit value 2^26=0x04000000) of the PDFUNS register
(0x10010344). I took this from the
jz4725 PM, which in this aspect works like the jz4740 in the nanonote.
We can set the value using the poke command
running it as:
poke -32 0x10010344 0x04000000
To test that it works, you can run:
$ stty -F /dev/ttyS0 57600 raw
$ while true; do echo bon dia; done > /dev/ttyS0 &
$ cat ttyS0
And cross the TX and RX wires.
cat should be printing lines saying "bon dia".
 Hardware mod to have a pluggable serial port
TP5 -- TXD
TP4 -- RXD
General view of the soldering work, in addition of the serial described above I also solder TP4 and TP5 to enable a second pin set of serial port 1 in the future, also a way to source at 3.3V possible low consumption serial modules
Same picture but commenting pinout and soldering points
Detail of the soldering on serial port 1
Detail of the soldering on second pin set of serial port 1
Detail of the 8 pins port glued to the speaker with epoxy
Hole to fit the 8 pins port, done with a dremel, in the same side as uSD card slot, removing the hole to hang the NanoNote, useless for me, also some internal plastic has to be remove with dremmel to make it fit under the speaker
also an edge of the battery room has to be "lowered" with the dremel to not squeeze the cables when putting things in place again, the edge beside the speaker
Detail of the 8pins port glued to the speaker, I select 8 instead 6 to have 2 free pins for posible future hardware hacking like use an external micro or "easing" the hardware usb-boot mode procedure
Detail of the 8pins port with all things in place again, it not adjust perfectly and the lids in this corner doesn't bind together again, but final result fits my needs
Now I can plug jumping wires to the port instead of having cables going out from Ben all time
Battery fits fine and the battery cover can be closed without problems
Hey after messing with internals it stills abling to boot!! :)
Serial console working OK using minicom, goal achieved! :)
Material used:11W thin tip iron, resined core tin, flutox gel(use it in very few minimal quantities and only in the cable never in the pads), thermoretractile cover, dremel like tool, thin cable (I extracted them from an old crappy usb cable), my old faithful multimeter(more than 20 years old and works like a charm), a slightly wet sponge to clean the tip of the iron, dual component epoxy glue and tons of patience to have pad,cable and iron aligned and ready to apply heat
short video without audio showing the serial console working with minicom using the ttl2USB cable
 Less invasive (and less robust) approach
under the battery, you need to put some solder on the contacts you want to lead out, so they become small bumps. I did not solder RxD, and I did connect the usb boot selection "jumper". Solder anything you need.
Cut a piece of (thin) paper to the right width, fold it and make small holes in it at the right spots. You find the spots by putting the folded paper in place and pressing on the bumps, so they leave some relief in the paper.
Put aluminum foil "wires" inside the paper (between the fold) to lead from the holes to the outside.
Insert it in the NanoNote.
Place the battery; this pushes the paper down so it makes good contact.