Maybe I'm missing something, but Arduino programs are usually
distributed as source code. If this is the case, the I2C address of the
display should be not a problem. If the problem is due to the display
library used, you can use another library that can be initialized with
the right address.
I'm curious about the real problem.
Regards,
Ignacio, EB4APL
El 26/06/2017 a las 2:29, Tom Miller escribió:
This is an update to discussions off list with Ben and Chris regarding
using the two line, 16 character display with the Packrats software on
the Arduino to control the TruePosition GPS board.
First, the ebay seller still has a few boards left and seems to take
offers of $40 for them.
Second, the display used with the Packrats software must use the I2C
address of 0x3F to work. The display needs to use the PCF8574AT I2C
I/O expander chip and not the PCF8574T. The later chip addresses
between 0x20 to 0x27 and will not work with this software.
Third, I picked up some of the "A" chips on ebay and they were marked
as A chips but addressed wrong. If you are going to change out this
expander chip, get them from someone like Mouser.
Next step is to find a suitable housing for this assembly.
Thanks all,
Tom
----- Original Message ----- From: "Ben Hall" <[email protected]>
To: "Discussion of precise time and frequency measurement"
<[email protected]>
Sent: Tuesday, June 06, 2017 7:46 PM
Subject: [time-nuts] TruePosition on the Arduino
Good evening all,
There is a saying: "a man with one watch knows the time, a man with
two is never sure." Clearly, this man wasn't a timenut and didn't
have GPS. ;)
I've been working on the Arduino code for the TruePosition boards
that quite a few of us have bought from the e-place.
It's my first real foray into both Arduino and the C language. (About
a million years ago I was reasonably competent with FORTRAN...the
1977 version...) It's mostly working - I can receive and display
pretty much everything that comes out of the unit minus a few
parameters. I can display it all on three pages on a 4 line by 20
character I2C display. Currently, the pages are selected by grounding
out one of two pins, or having nothing grounded. Eventually, I'm
going to change this so that it changes display pages when a button
is pressed. I don't have lat/long display yet, nor can I handle
doing a survey, but those are coming.
My code probably would make a real programmer vomit, but hey, it
works. :)
Back to the man with multiple watches. I was having a very
frustrating issue with my TruePosition and Arduino code being one
second behind my other sources of time. I went round and round,
trying to figure out why the TruePosition thru the Arduino was a
second slow. In the end, it turns out that it wasn't slow...it was
correct...but that my other sources of time have errors.
I finally proved this to myself by firing up an old Trimble Lassen LP
GPS board unit equipped with a 1PPS tick light and serial
output...and it was clear that it matched the TruePosition after
correcting for the fact that my TruePosition / Arduino code only
updates the display when 1PPS is asserted high...but that the Lassen
LP displays the serial message before it becomes valid at the next
1PPS tick.
I was slightly embarrassed...I should have known that the other
sources of time all had sources of error beyond my control. I should
have trusted the TruePosition as being the purest, least complicated,
and the path I knew the most about between GPS and my eyeballs.
So for a while...the statement was true. With my multiple sources of
time...I really didn't know the time. But it was also untrue, as
when I got agreement between two very "pure" sources of time, I knew
everything else was wrong. ;)
I'm getting to the point that once I've got the button logic working,
I'll send out my source to anyone who wants to take a look at it or
use it. I will stipulate one condition - you can't make too much fun
of how poorly programmed it is. ;)
thanks much and 73,
ben, kd5byb
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