[aprssig] [OT] Some interesting Display Developments with K107
brianbr at mac.com
Mon Sep 11 16:13:55 CDT 2006
Its been a while and I have been busy on the bench the last few days.
Since there are dozens of people on both these lists who have
purchased my K207 serial LCD controller I am posting these two notes;
(1) I found a nice display at All Electronics <http://
www.allelectronics.com>. Their part number is LCD-105. It is a non-
backlit 2 line by 40 character display made by Goldentech. The data
sheet is a little unclear, but it turns out it is HD44780 compatible
and therefore compatible with the Anderson chips in the K107. The
connection is a ribbon and one end is anchored to the display. To
connect to the K107 you install a 2x7 pin header and the bottom side
(solder side) of the K107. The Anderson #117 chip is cognizant of the
2x40 geometry so that is no problem.
(2) I started mucking withe PICAXE chips and the rule of thumb is
generally that you are stuck with 2400 baud serial. But I found that
you can put the display onto the programming out port (P0) and use
the "SerTxd" command which normally outputs at 4800 baud. However use
of the command "Setfreq M8" to up the internal clock to 8 MHz then
that baudrate jumps to 9600 baud and you are set! ... well ...
almost! The "SerTxd" driver is made to talk with a PC. Sooooooo ...
you need to set the input type jumper to RS232/INVerted. I did this
with a PICAXE 08M, but should work with any PICAXE supporting "SetFreq."
You must consider with regard to the PICAXE and the Anderson PIC #117
each operating on the internal oscillators which are subject to
thermal drift. IF, they both drift, and in OPPOSITE directions they
COULD begin to show framing errors while trying to talk to each
other. It was this reason the Peter Anderson created the #108/#118
chips using a 4 Mhz resonator which is far less prone to drift and is
almost guaranteed not to drift beyond the PICAXE. So its on a chip by
chip basis, but definitely worth checking out.
There is discussion, pix, and some sample code for both these issues
on the K107 section of my Tech Blog ... see the link below.
cheers ... 73 de brian riley, n1bq , underhill center, vermont
<http://web.mac.com/brianbr/> Tech Blog
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