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Forum Index : Microcontroller and PC projects : KEYDOWN Bug
| Author | Message | ||||
| MM_Wombat Senior Member  Joined: 12/12/2011 Location: AustraliaPosts: 139 |
Hi, I made this program...V4.3 ? "press a few keys, then press (i) for input"
Do mykeydown=KeyDown If mykeydown <> 0 Then GoSub branchout Pause 100 Loop branchout: If mykeydown = 105 Then Input "Why does it put in the keydown presses?";test$ ? "you inputted ";test$ EndIf Return When executing I typed the alphabet "abcdefgh", then when I typed (i) it wanted my input, but the alphabet was already there with the (i). I typed good and the string it returned was "abcdefghigood" Is this a bug.... Regards Dennis Keep plugging away, it is fun learning But can be expensive (if you keep blowing things up). Maximite, ColourMaximite, MM+ |
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BobD Guru  Joined: 07/12/2011 Location: AustraliaPosts: 935 |
Nick raised this as a possible bug when he wrote his latest game. The answer was that Keydown does not clear or take a character from the keyboard buffer. I think Geoff said this behaviour will be changed in V4.4 when released. If so then what is the difference between Keydown and Inkey$ ? |
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| MM_Wombat Senior Member Joined: 12/12/2011 Location: AustraliaPosts: 139 |
Hi, I was using inkey$, but i thought this would be easier for my maxifont program and free up 254 bytes of memory from the resultant text$=inkey$ I should read the forums more often... thanks . will have to change it back.. Regards Dennis Keep plugging away, it is fun learning But can be expensive (if you keep blowing things up). Maximite, ColourMaximite, MM+ |
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MicroBlocks Guru Joined: 12/05/2012 Location: ThailandPosts: 2209 |
You could empty the keyboard buffer with inkey$ once you got your keydown value. You do not need to store the inkey$ value because you already have the keydown value so you still save the bytes. Microblocks. Build with logic. |
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Nick Guru Joined: 09/06/2011 Location: AustraliaPosts: 512 |
INKEY$ has the added disadvantage of including key delay and the key repeat strobe which is not what you want when using the keyboard in a fast action game. For example... In my game, if I wanted to move the man character to the right, I would press the right arrow key. INKEY$ would send that key's code and my man would move to the right 1 position. But, INKEY then delays for a short time sending 0's even though the right arrow key is still being held down and I want the man character to continue moving. The man instead stops since it's reading 0's. When the key delay is finished, it send the key's code again and the man continues walking. But, now the key repeat kicks in! This sends a few 0's then the code then a few 0's again then the code... and this repeats for the duration of the key being pressed. The overall effect is that the man doesn't move smoothly and responsively. I can make my software ignore the 0' but that tended to create a lag and that reduced resposiveness also. Hence the KEYDOWN command which is essentially like INKEY$ but doesn't throw out the 0's. Nick |
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| BobD Guru Joined: 07/12/2011 Location: AustraliaPosts: 935 |
Thanks Nick |
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| MM_Wombat Senior Member Joined: 12/12/2011 Location: AustraliaPosts: 139 |
Hi, @ tzadvantage you mean like, just before my input command : inkey$ : input " what I need for input";test$ regards dennis Keep plugging away, it is fun learning But can be expensive (if you keep blowing things up). Maximite, ColourMaximite, MM+ |
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| MicroBlocks Guru Joined: 12/05/2012 Location: ThailandPosts: 2209 |
@Dennis You would need to use a while loop and repeat the inkey$ until the keyboard buffer is empty. Another good spot is right after using the keydown function. If you use the inkey$ once you know there was a keypress the inkey$ is fast and empties the keyboard buffer right away. Once the keydown function is fixed in the next version you can remove those inkey$. mykeydown = keydown if keydown <> 0 then inkey$ gosub branchout end if Microblocks. Build with logic. |
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| MM_Wombat Senior Member Joined: 12/12/2011 Location: AustraliaPosts: 139 |
@ TZAdvantage Thanks I thought afterwards it would be better there, where you suggested.. Dennis Keep plugging away, it is fun learning But can be expensive (if you keep blowing things up). Maximite, ColourMaximite, MM+ |
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| JonS Newbie  Joined: 28/02/2013 Location: United KingdomPosts: 4 |
I need someone to validate this additional Inkey/Keydown bug as it could just be my keyboard. Before 4.3 (possibly 4.2 also) Inkey$ would report additional values when the SHIFT key was held down in conjunction with the Cursor keys. So Right Cursor would give 131 and SHIFT+Right Cursor 163. Since KEYDOWN, both Inkey$ and KEYDOWN no longer report the SHIFT+Cursor - it stays at the Cursor only vlaue. But, as stated this could just be my keyboard (although unlikely as everything else functions Ok) - can someone confirm either way - and if at all possible suggest an alternative way to read both as I need the ability to do this for a Sprite Editor program i'm working on. Many thanks for any help.. Jon Silvera (teamFUZE) |
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| shoebuckle Senior Member Joined: 21/01/2012 Location: AustraliaPosts: 189 |
Jon, Right Cursor and Shift Right Cursor return the same value on my keyboard too. It is the same with all the cursor keys inc Home, End, Page Up and Page Down, whether dedicated cursor keys or keys on the numeric keypad with Num Lock off. Cheers, Hugh |
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| shoebuckle Senior Member Joined: 21/01/2012 Location: AustraliaPosts: 189 |
I have just gone back through a number of MMBasic versions with the same result back as far as v3.0 using Do
? "Press a key" Do a$=Inkey$ Loop until a$<>"" ? Asc(a$) Loop Looks to me like a bug if the shifted value is supposed to be different. Cheers, Hugh |
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| BobD Guru Joined: 07/12/2011 Location: AustraliaPosts: 935 |
The shift function only works with the F1 to F12 keys. However the Control key should / may affect the other keys like left and right arrow. Refer to the V4.3 manual page 53, the first paragraph below the table. |
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| MM_Wombat Senior Member Joined: 12/12/2011 Location: AustraliaPosts: 139 |
Hi, SHift-Right cursor changes nothing , but ctrl-right cursor changes the value of keydown for me. ctrl-any key changes most things Keyboard ps/2 BTC Model E5XKB5199 Dennis Keep plugging away, it is fun learning But can be expensive (if you keep blowing things up). Maximite, ColourMaximite, MM+ |
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Geoffg Guru Joined: 06/06/2011 Location: AustraliaPosts: 3194 |
Yes, the shift modifier has never worked on the arrow keys. The output from a PS2 keyboard is very hard to decode and getting the shift modifier to work correctly is still on my todo list. Geoff Geoff Graham - http://geoffg.net |
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| MOBI Guru Joined: 02/12/2012 Location: AustraliaPosts: 819 |
Tell me about it! I built a dual pic decoder (PS2 to I2C) that pretty closely replicates the PC keyboard with all keys as ascii value. It has a number of lookup tables e.g. Shift, control, Alt etc but not combinations of say ctrl-alt. It took up quite a bit of firmware space on a 16F88. The first chip did the decoding and output as 8 bit parallel and the second chip did the i2c. It could hook up to the MM either in parallel or i2c if someone wanted something close to a "real" PS2. David M. |
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| MM_Wombat Senior Member Joined: 12/12/2011 Location: AustraliaPosts: 139 |
Hi all, @TZAdvantage your code snippet suggestion won't work as inkey$ is not a standalone command. mykeydown = keydown if mykeydown <> 0 then inkey$ gosub branchout end if so I changed it to... do mykeydown = keydown if mykeydown <> 0 then null=asc(inkey$) 'send keyboard buffer to bit bucket as number(4 bytes), not string (256 bytes) gosub branchout pause 100 ' whoa slow down, goes too fast end if loop branchout: 'check which key pressed return Dennis Keep plugging away, it is fun learning But can be expensive (if you keep blowing things up). Maximite, ColourMaximite, MM+ |
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