Serial console
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.
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[edit] Pinout
See also here. If you want to know that how to soldering these test points, you can also see here.
[edit] Connection
- 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.
[edit] Software
- 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
[edit] 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) HW wiki.
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".
[edit] Hardware mod to have a pluggable serial port
TP5 -- TXD TP4 -- RXD
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