Hi all,
I need a bit of advice on the best and most efficient way to read 10 I/O pins. Main will be constantly scanning the pins and anytime one of the 10 pins goes logic high it will be required to be read. I have thought of having 10 IF statements in main but i dont think this is the best way. Is there another way other than using IF and also a way of prioritising pin reading?
Look forward to your help.
Thanks,
Rocketman46
What type of system are you using?
Is there an operating system?
Is it some kind of embedded system?
Unless your system has dedicated hardware for generating interrupts when a pin goes high, there's no other way you can do this. You may or may not want to add a delay between the checking btw, that depends on the power consumption and accuracy you're aiming for.
Devoted my life to programming...
Hi Jim,
Thanks for your reply.
I am using a 16bit micro running embedded c. I just tried to keep the question simple and c related.
Cheers,
Rocketman46
Are all 10 pins in the same 16-bit I/O register?
If you dance barefoot on the broken glass of undefined behaviour, you've got to expect the occasional cut.
If at first you don't succeed, try writing your phone number on the exam paper.
Hi Salem,
No they are not all on the same I/O port. If it is beneficial i could possibly modify to one port. Do you have a better solution?
Thanks,
Rocketman46
I suppose we could spend some time making wild guesses about which uC you're using, which pins you're trying to read and how they're organised for access from the CPU.
Or you could fully disclose what you know already.
If you dance barefoot on the broken glass of undefined behaviour, you've got to expect the occasional cut.
If at first you don't succeed, try writing your phone number on the exam paper.
There's nothing inherently wrong with using ten "if" statements, if that will get the job done. If this satisfies your requirements without detriment, then go for it. This is where low-level logic shines.Originally Posted by RocketMan46
As Salem alluded to, if all of the bits are on a single register, you can save the previous register value and only act if the register value changes.
If you need to get fancy, it's surprisingly easy to implement a primitive "OS" on an embedded device, using just one interrupt (creating perfectly timed slices to break up the work). I won't give it away, since it's not my work, but if you want I'll share author who explains it.
