PSoC4000s & The SmartIO – Part 5

This is my last post on the SmartIO.  This time, I am going to describe how to use the SmartIO to trigger an interrupt.  For this project I will start from the “SmartIOCountUp” project.  That project is a 3-bit counter.  I thought that I would choose one of the states (000) and trigger an interrupt when that state is hit, then toggle the P25 user led.  I will keep data4, and gpio 3,6,7 exactly the same.  I will use gpio 2 to trigger the interrupt, which can be accomplished by setting it up as an output.  Here is the SmartIO configuration:

The next step is to use LUT2 to look for the “000” state and to create a rising edge.  The other states will be 0.

After making the modification to the SmartIO the next step is to fix the schematic.  To do this I add a pin for P22, its configuration is on the next screen.  In addition I move the P25 (aka the BlueLED on the master board) to pin by itself.

To configure the P22 pin.  There is a trick that is required to make the pin be both an output, so that it can be connected to the SmartIO LUT as well as an Input, so that it can be connected to the Port 2 interrupt.

After setting up the pin to be both an Input and an Output you need to configure the pin to have an interrupt on the rising edge.

Then I assign the pins.

The last step is to make the firmware.

• Lines 4-9 create an interrupt service routine
• Line 18 registers the interrupt service routine to be called with the Port2 interrupt is triggered
• The rest is the same as before

When I run this, I see the Blue LED toggle each time it gets to state 000 (which is all three LEDs on as they are active low).

You can find this PSoC Creator workspace on github in the directory called “SmartIO”.  This project is called “SmartIOInterrupt”.