[TI-ASM] The in's and out's of key input

crzyrbl · Post by **crzyrbl** » Thu 07 Jun, 2007 1:33 am

Can someone explain in depth how to use the 2 following instructions:

in
out

thnx in advance

Post by **Dwedit** » Thu 07 Jun, 2007 2:46 am

You read a list of Ports and what they do from a website such as WikiTI.

crzyrbl · Post by **crzyrbl** » Thu 07 Jun, 2007 5:23 am

I should probably be more specific. I'm having trouble with getting keyboard input. I'm still relatively new to assembly.
(eventually I also want to know how to detect multiple keypresses as well)
*title changed

Post by **Dwedit** » Thu 07 Jun, 2007 6:00 am

http://wikiti.denglend.net/index.php?ti ... s:Ports:01

Halifax · Post by **Halifax** » Thu 07 Jun, 2007 8:29 pm

Have you tried reading Asm in 28 days? I recommend that because it explains the exact thing you want to do with multiple keypresses and everything else.

King Harold · Post by **King Harold** » Thu 07 Jun, 2007 8:49 pm

What Asm in 28 days doesn't tell though is that sometimes multiple keypresses 'mess up' and leave result differing from what you'd expect. Single keypresses should always work fine though, and you won't have much trouble if you only check the arrows for multi presses.
If you write a little program displays all groups then you should be able to figure out which keys you can 'safely' press together.
(you might want to use the key scanning routines that I have been going on about, use the one with INI - it's cool

)

edit: you can have real trouble when there are more than 3 being pressed, I don't know whether many games even need that because you only have 2 thumbs but take it into consideration when you're thinking about funky combo's and 'special moves' etc.

crzyrbl · Post by **crzyrbl** » Fri 08 Jun, 2007 5:15 am

Ah, I see, I have to use the BIT instruction then...hmm, I think I got it now

. Are there problems with detecting 3 buttons? For example two directionals and 2nd or something around there?

King Harold · Post by **King Harold** » Fri 08 Jun, 2007 9:00 am

Im not sure about that one, you'd have to try in on HW since the emulators might not be 100% accurate.
You don't HAVE to use bit operations, but that's probably safer. If possible, use a shift operation and catch the carry, it's faster. If you only have to test some middle bit and throw the rest away then you could use logic AND.

Jim e · Post by **Jim e** » Fri 08 Jun, 2007 10:38 am

The effect that King Harold is talking about is caused by the grid setup of the keyboard. If 3 or more buttons are being pressed its possible to get bad reads from the key port. Basic rule of thumb is this: If a particular bit is reset in more than one group, then those groups will return the same value, which will be all those groups AND together.

Code: Select all

     | | 
-0000+0+0
 00000000
-0000+0*0

The idea is the plus signs are actually being pressed, where as the asterisk is a false press. Typically this problem doesn't occur, its not easy to hold the combination that this can occur in. For gaming, coders usually stick to only certain groups.

To answer your question Arrows, 2nd, mode, alpha & F1 will all be okay to use together in any key combination.

Halifax · Post by **Halifax** » Fri 08 Jun, 2007 7:54 pm

Well I forget right now but isn't F1-F5 in one group I don't know. But I have always had this question. With those could you detect up to 5 keypresses or anything?? Since they are all or'd together. This would be useful for something like Guitar Hero

crzyrbl · Post by **crzyrbl** » Fri 08 Jun, 2007 10:37 pm

I'm having trouble getting my emulator to recognize the combination up+left+2nd, yet all the other combos work (2 arrows and 2nd that is). Is this just an emulator problem or is it deeper than that?

Andy_J · Post by **Andy_J** » Sat 09 Jun, 2007 1:05 am

It might actually stem from your computer's keyboard, due to the same matrix problems as outlined above for the calculator's keypad -- computer keyboards are made the same way.

crzyrbl · Post by **crzyrbl** » Sat 09 Jun, 2007 1:13 am

that's exactly right. I used the mouse to press 2nd and all three registered correctly. You get the gold star!