While there is nothing groundbreaking about a discussion of serial communications, we felt that it was important to address this topic early on in the Fold, Spindle, or Mutilate series. Being able to interface with various hardware via the serial port is a key tool in any experimenter’s or developer’s tool kit.
Many input and output devices, such as the serial terminal and the Point Of Sale LED display featured in this episode, as well as most sensors and other hardware peripherals communicate using a serial link. Reading and writing data to and from a microcontroller is also typically accomplished via a serial connection.
[ More Episodes – FSoM Archive ]
The perl script used to drive the POS display in the opening sequence follows:
perl -MTime::HiRes -e '@a=qw(Fold Spindle or Mutilate); \
while(1){foreach(@a){ print $_."\r\n"; \
Time::HiRes::sleep(0.5); print "\cL"; }}' > /dev/<your serial device>
The bash script used to display uptime on the POS display:
while true; do uptime | awk '{print "uptime: " $11 " " $12 " " $13}'; \
sleep 1; printf "\f"; done > /dev/<your serial device>
Spawning Getty (login) from Screen
screen /dev/<your serial device> <baud rate>
and then from within screen:
CTRL-A SHIFT-: exec ::: /<path to getty>/getty std.9600 (substitute the appropriate reference to a definition within gettytab for std.9600 as needed)
Wikipedia links for more information:
