A commenter asked for the schematic of the analog interface I made using an MPC3008. I seldom include schematics with my posts for several reasons. I don’t expect anyone to duplicate exactly what I have done, so if I post anything, it is just partial drawings of the most important concepts. But the biggest reason is that I almost never create true schematics and I am too busy to do it just for the blog. Something that I do frequently do is a simple drawing that helps me lay out the components onto the perf board. Then I use that as my guide when I build the device. These are seldom complete enough to be useful to others. In this case, however, the entire circuit is shown.
Image may be NSFW.
Clik here to view.
This is what I created for the analog interface. The 7-pin header connects to my main circuit board where I have two SPI ports – one with CE0 connected and the other with CE1. The 3-pin header allows me to select the reference voltage for the MCP3008. The blocks along the bottom are screw terminals. See the post Analog Interface for a picture of how this looked when built.
I will probably be pulling this old board out again to experiment with a thermocouple that I just received. I need it for the flame detection on my Home Brewing Automation setup.
Image may be NSFW.
Clik here to view.

This is what I created for the analog interface. The 7-pin header connects to my main circuit board where I have two SPI ports – one with CE0 connected and the other with CE1. The 3-pin header allows me to select the reference voltage for the MCP3008. The blocks along the bottom are screw terminals. See the post Analog Interface for a picture of how this looked when built.
I will probably be pulling this old board out again to experiment with a thermocouple that I just received. I need it for the flame detection on my Home Brewing Automation setup.