My friend Jeff - KO7M came by today with known working tools (BusPirate) and parts (Si570). We had been troubleshooting my VFO problem via e-mail and over the phone, but we were not getting anywhere.
|Jeff at the Microscope|
1. My BusPirate fails to generate I2C SCL (clock) signals, even though many other functions seamed to work. Without an SCL signal data can not be received by a Device Under Test (DUT), even though the BP can receive Data using the same SCL wire from the DUT.
2. The failure of my VFO was the Si570 itself, it would not accept I2C data or commands, even though it produced RF on the output. It is DEAD.
Before today, I had created an Si570 BreakOut Board (see previous post), with just the Si570 and Header pins. My intent was to verify that the BP was working as expected, but because there are also wires, clips and connectors that could have failed results were inconclusive.
|Si570 Breakout Board|
|Si570 Breadout Board|
Today - Jeff to the Rescue !
With Jeff's known working BP we quickly determined my VFO Module (i.e. Si570) was bad. Other I2C devices; the two Si570 Breakout Boards and a Real Time Clock Module (RTC) all work as expected.
Because yesterday I had used my last Si570 on the second Si570 Breakout Board, I could not repair the VFO Module. but we could build an Si570 Breadout Board Adapter that connects between the Breakout Board to the Minima CPU Module. I had previously designed and did a layout for the Adapter with DipTrace, for just such an occasion. We spent the rest of the afternoon building and testing the Adapter Board.
The Adapter Board tested correctly with Jeff's BP as we hoped. It also tested and worked with the Minima CPU Module.
|Adapter Board Connected to the Minima CPU|
and a Coax Cable, the Si570 Breakout Board in the Foreground
|Stacked and Ready for Testing|
|34.2MHz (14.2+20) As Shown|
with 10X Expanded Sweep Scale
|Minima CPU Module and |
Temporary VFO Module
I can now continue my experiment Minima Transceiver Project.
I need to order a few more Si570's, and a new BusPirate (or troubleshoot and fix it).