multiple port interrupts

[scamanderriver]

Hi Guys
I am using all my port B pins as interrupts on a 40x2
SETINT OR %00000000,%11111111,B
I am wondering if it is possible to set interrupt across multiple ports.
ie. using combinations of PortA pins and B pins and C at the same time.
I hope someone can enlighten me
cheers

 

[nick12ab]

Apparently "only one input pattern is allowed at any time" so probably not. However you could try using 16 bits instead of 8 which might allow you to use port C and port B (specifying B as the port) because the C pin numbers come right after the B pin numbers.

 

[westaust55]

Using a 16-bit value for the input state and mask will not help.
As the PICAXE manual states:

- input is a variable/constant (0-255) which specifies input condition.
- mask is variable/constant (0-255) which specifies the mask

If you enter a value with more than 8 bits only the lowest 8 bits will be used.

 

[inglewoodpete]

Hi Guys
I am using all my port B pins as interrupts on a 40x2
SETINT OR %00000000,%11111111,B
I am wondering if it is possible to set interrupt across multiple ports.
ie. using combinations of PortA pins and B pins and C at the same time.
I hope someone can enlighten me
cheers

Interrupts can only occur on the nominated port.

However, with efficient selection of pins, you can create diode-or functions by wiring diodes from pins of other ports to one pin of your nominated port. That "one pin" will need a pullup or pulldown resistor to keep the "normal" (off) state. Within the interrupt routine you will need to poll each of the appropriate ports to get a quick snapshot of the input conditions that triggered the interrupt.

 

[scamanderriver]

Thanks guys, I appreciate your help

However, with efficient selection of pins, you can create diode-or functions by wiring diodes from pins of other ports to one pin of your nominated port. That "one pin" will need a pullup or pulldown resistor to keep the "normal" (off) state. Within the interrupt routine you will need to poll each of the appropriate ports to get a quick snapshot of the input conditions that triggered the interrupt.

This is very clever work around thanks, I'll have a play with it, cheers

 

[Hans Michlmayr]

If you need up to 16 input interrupts you could interface a PCA 9555 via i2c , the 9555 has its own interrupt output for input changes. This output can then be connected to one of the 3 normal PICAXE interrupts. The interrupt service routine then has to evaluate the state change(s) in the PCA9555 before deciding how to respond . (sounds more complicated than it is).

 

[westaust55]

@ Hans,
Welcome to the PICAXE forum.

A good suggestion there if the user wishes to utilise an additional chip (sometimes PCB real estate is deemed to be an issue).

Another similar chip is the MCP23017 providing 2 x 8-bit ports with two interrupt outputs that can be combined.