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PUT THE GP-22050 TO WORK

While I was putting this column together, the lead engineer for the real-world mechanical project I told you about brought over the breadboard for me to use while writing the application code for the final box. His idea of a breadboard was the subject of Photo 3b. My job was to consolidate the functions of the three separate microcontroller subsystems into a single microcontroller subsystem that could monitor and control the various motors and switches. However, before I began work on the final consolidation, I was tasked with ensuring that all of the signal levels from the LCD control module were correctly timed and administered. It was a great opportunity for the GP-22050 sitting on my messy desk!

Using the GP-22050 eliminated the one-by-one, probe-and-run drill I normally do when mating hardware to firmware. This particular project’s main microcontroller had six major motor control, fan and valve outputs, a pair of TRIAC driver outputs, and seven switch closure inputs that I needed to validate. Adding everything up, I had 15 monitor points, which meant I could put them all up on the GP-22050’s I/O interface at the same time with one GP-22050 I/O pin to spare.

I like to keep things as simple as possible, so I configured the first 15 GP-22050 I/O pins for input duty and left the triggering and control lines in a benign state (see Figure 2). The GP-22050’s Real-Time Monitor mode checked the state of each input pin every 100 ms, which was plenty fast for my application. I didn’t use any triggering because I simply stepped through the breadboard code and noted the signal levels as I went.

(Click here to enlarge)

Figure 2—This pseudo schematic assumes that all of the necessary driver circuitry is placed ahead of the breadboard’s physical devices. It’s also assumed that only the logic levels needed to activate the driver circuitry are being monitored by the GP-22050. Note that the control/trigger pins D16–D21 are idle.