I completed a bread board of the circuit that tracks the temperature of the MOSFETs. This circuit plugs into the Starter Kit I/O Expansion board. This setup allows various pieces to be developed before integration.
I have modified the original schematic to add buffer amplifier for a low impedance input to the A/D converter. My thanks to the idea contribution of Bill….WB6BNQ. Thanks Bill!
I wrote some simple code to run the part. See image below:
This is my logic analyzer that lets me see the signals much like a scope (only better for program troubleshooting). The top signal is the chip select which is present for about 17uS. The SCK1 signal is missing (a problem) but I find it at SCK2 instead of SCK1. Note the two bursts of 8 clocks. This clock moves data in and out of the MC3202 A/D chip. The signal at SDO1 is the data sent to the A/D which is a decimal 5 (test data). Strangely enough I see the same signal on a unrelated pin, RC2. So I have initiated a trouble ticket with Microchip to find out if it is me or something not right with the I/O Expander board.
Sometimes, it is toughest to get the code started where you can make progress. I want to get this resolved quickly.
We are moving forward and allowing builders to put up a $200 down payment to speed up the development. Those who respond are rewarded with a place ranked in line for the first deliveries.
Spread the word about this group build amplifier project. We need at least one hundred committed builders to make it possible to have good pricing on materials.
This is an accounting of project expenses and R&D funds available to date. You can help by either a purchase of R&D expense as an interested party to help with development or you can make a $200 down payment which translates to a $200 discount off of the sales price and a early place in line.
This week I plan to go back into the artwork and add the buffer amplifier amplifier added to the temperature measurement and then get the bare minimum of prototype boards ordered for proof of design and performance. I will also need to get a milled heat transfer block fabricated that mounts to the MOSFET’s and the heat sink. See my earlier mechanical drawings.
The design is fluid at this moment and we have all our options open. If you have not joined the project, it is not too late. Send me an email with your call and delivery information: firstname.lastname@example.org
73 K5OOR – Virgil