[McHUG] Si570 Thoughts

[Peter Morton]

Well, Rich-

Sounds like a plan.

Yesterday, I dug out my son's C and C++ text books after spending a couple 
of days trying to decipher example C programs and the help files for the 
software that Steve included in his "parts" box. I'm beginning to understand 
a lot of the C syntax.  Subtleties such as placing ++ in front of a variable 
name in lieu of after a variable name were not apparent until I dug into the 
text books.  Anyway, I'm getting there.  I've started rewriting the PICAXE 
morse program to run in C on the Atmel AVR as an exercise.

After I master the rewrite, I plan to look into a program for controlling 
the SI570.  I was looking earlier this week in the Yahoo Softrock group 
files section at the program that W0CNN wrote for the AVR and also at the C 
program on the Silicon Labs site.  When reading these programs, I become 
more aware of how unfamiliar I am with the C language.  But, I'm getting 
there.

Steve certainly knows how to tweak my interest in this stuff.

I discovered that the bus contention that I was seeing on the SDA line to 
the SI570 (using a scope) was the ACKnowledge pulse being sent back by the 
SI570 at the end of each byte it receives.  The parallel port software I'm 
using does not have the proper timing needed to prevent the ACKnowledge 
pulse from the SI570 from occurring during the extended eighth bit of a byte 
after the bit has been clocked..  I don't know yet if this is causing the 
frequency error I'm experiencing.

Unfortunately, time in running out for income tax preparation and I have to 
do mine and two of my kids.  I'll have to take a break from the AVR for a 
day or so soon.

I tried out the Hyper-Dog Hyper-Hanger that I put together (showed you at 
Stables last Friday).  It works well.  However, it doesn't launch the ball 
high enough to get over the tree where I wanted to elevate my Zepp.  In 
fact, it only can get the line as high as the antenna is now.  Very 
disappointing.  May have to go back to the sling shot and sinker.

Well.  Off to BARC.

-Pete


----- Original Message ----- 
From: "Rich Mitchell" <geobra at att.net>
To: "McHUG Reflector" <mchug at mailman.qth.net>
Sent: Saturday, March 29, 2008 7:53 AM
Subject: [McHUG] Si570 Thoughts


>I have been playing with the Si570 frequency generator because it looks 
>like an ideal peripheral for our ATMega168 BareBones Board.  Here are my 
>building blocks:
> 1. BareBones Board Rev C - The ATMega168 supports TWI (A4, A5)
> 2. Si570 on the WB6DHW board
> 3. W0CNN software using TWI approach
>
> I have been able to load the W0CNN software into the BBB.  Now its input 
> controls are pushbuttons on the STK500 development board with some read 
> out to LEDs.  These things we can change.  It looks like on boot it will 
> generate a frequency word for 10 MHz.  So just loading and attaching the 
> WB6DHW board should give us a quick test.
>
> I have put together a WB6DHW Si570 board (not tested yet).  I hope to 
> attach it to a carrier board (from RadioShack) that would give me 8 pins 
> similar to the DDS60 board.  The hope is that with different software your 
> could interchange the two in the same Radio MotherBoard.  The DDS60 has 
> the following pinouts:
> 1. Load
> 2. Clock
> 3. Data
> 4. +5 out
> 5. Ground
> 6. RF out
> 7.
> 8. V++ in
>
> For the Si570 I would wire the carrier board to have:
> 1. +5 reference from BBB (similar to load ??????)
> 2. SCL (Clock)
> 3. SDA (Data)
> 4.
> 5. Ground
> 6. RF out
> 7. RF out (does the Si570 have to have 2 RF outs?????)
> 8. V++ in
>
> If this works, I suggest we redesign the WB6DHW Si570 board to first, have 
> through hole parts wherever possible.  The Si570 is the largest part on 
> the board right now.  We could give up a bit of compactness for ease of 
> building.  Second, standardize the pins after the DDS60 where possible. 
> An easy to build frequency generator would be a great asset for McHUGgers.
>
> Rich, N3III
>
>
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