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Forum Index : Microcontroller and PC projects : Byte Wide Operations Using INP & OUT.
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donmck Guru  Joined: 09/06/2011 Location: AustraliaPosts: 1313 |
I may be wrong, but it appears all I/O is done with single pins only. What if we had two 10 bit wide ports, and used the old TRS-80 byte commands as follows: INP(X) Inputs one byte from port number x. OUTx,y Outputs byte y to port x. Sure it's a 10 bit wide I/O port, but I don't think there is a problem, is there? Cheers Don... https://www.dontronics.com |
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thetinkerer Regular Member  Joined: 16/06/2011 Location: AustraliaPosts: 68 |
I am with you on that one Don. |
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| donmck Guru Joined: 09/06/2011 Location: AustraliaPosts: 1313 |
If we can get another couple of supporters, I'll add it to the wish list. Trouble is, I am not using the unit yet, and getting into the language, so I may be missing things at times. Like the CLS. Someone said to me, hey, it hasn't got a CLS, so I added it to the wish list. I was wrong. It was staring me in the face, if I had read the manual a little more. So two more positive comments on this one, and I'll add it to the Wish list. I don't know how many items I can add to the poll. This may test it. It may test Geoff too. 
Cheers Don... https://www.dontronics.com |
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BobDevries Senior Member  Joined: 08/06/2011 Location: AustraliaPosts: 266 |
Hey Don, You have my support on that. It's actually something I had thought of earlier, but then forgot about. Regards, Bob Devries Dalby, QLD, Australia |
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James_From_Canb Senior Member Joined: 19/06/2011 Location: AustraliaPosts: 265 |
Don, So you want to take an 8 bit value in a variable and send one bit to each of 8 ports? That's already done in the LCD.BAS code. Admittedly it uses a call to a subroutine to do it, but once you have the subroutine you can ignore the complexity and just call it. This is a bit like the RISC Vs CISC discussions of years past. If we can keep the core small we can add the routines we need, leaving memory for other stuff. In hindsight this also covers my thought about having a SHIFT command. There's no real need for it, because we could use a subroutine to shift right by multiplying the value by 2, and shift left by dividing. My mind is aglow with whirling, transient nodes of thought careening through a cosmic vapor of invention. Hedley Lamarr, Blazing Saddles (1974) |
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stuarts Senior Member Joined: 15/06/2011 Location: AustraliaPosts: 199 |
Don, while there is a CLS, I think it would be nice if its functionality could be extended to the "serial" connection via USB. I realise that this would be dependant on the terminal emulator that one used being compatible with whatever escape sequence was sent by the CLS command. I think that it could also be assumed that everyone has access to a vt100/ANSI terminal emulator. Stuart Time is nature's way of keeping everything from happening all at once. |
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| BobDevries Senior Member Joined: 08/06/2011 Location: AustraliaPosts: 266 |
Stuarts: Regarding CLS to a terminal, the usual one would be CTRL-L CHR$(12), but that does nothing on the Maximite (as yet). James_from_Canb: I see your point about adding byte output. Adding commands to MMBasic which could fairly easily be done in BASIC subroutines, makes us lazy (IMHO). Doing some research on the subject usually provides clues on how to do it. Regards, Bob Devries Dalby, QLD, Australia |
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| donmck Guru Joined: 09/06/2011 Location: AustraliaPosts: 1313 |
Thanks James and Bob, on the Byte wide commands. I can see the double edged sword. I'll leave it there, because it got there, and at least it should create a healthy discussion on the merits of each approach. We don't do fisticuffs here yet, do we? 
Cheers Don... https://www.dontronics.com |
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| donmck Guru Joined: 09/06/2011 Location: AustraliaPosts: 1313 |
Sorry Stuart, I must have missed your point about CLS at our Special Meeting last night. 
Does this mean that CLS won't always work on all Terminal Emulators, unless we throw the vt100/ANSI terminal code at it? If you can rephrase the CLS, as a wish list question, I will add it to the list. Cheers Don... https://www.dontronics.com |
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| BobDevries Senior Member Joined: 08/06/2011 Location: AustraliaPosts: 266 |
I have just examined the LCD.BAS file, and found that the output routine (lines 13000-13150) depends on the fact that any value other than 0 will drive a pin high (in digital mode) even a negative value! If eight consecutive pins were toggled this way, I wonder what the time delay would be between pins and between first and last pins, and how important would this timing be? I also just noticed that both the LOAD and KILL commands do NOT accept a directory name as part of the filename, again requiring a CHDIR before (and after) each use on a file in a directory other than the current working directory. so, LOAD"dirname\prog.bas" doesn't work, you need to use CHDIR"dirname":LOAD"prog.bas":CHDIR".." Regards, Bob Devries Dalby, QLD, Australia |
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| James_From_Canb Senior Member Joined: 19/06/2011 Location: AustraliaPosts: 265 |
I think I recall the Maximite processing 30,000 instructions per second - so maybe 1/3000 of a second to write values to all 8 pins? The time taken doesn't matter for the LCD program because the values are loaded onto the 4 data pins then the pins 12 and 11 are toggles to accept the data. My mind is aglow with whirling, transient nodes of thought careening through a cosmic vapor of invention. Hedley Lamarr, Blazing Saddles (1974) |
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| James_From_Canb Senior Member Joined: 19/06/2011 Location: AustraliaPosts: 265 |
MMBasic has a Timer command, so I can give you a real answer rather than estimating. [note: I didn't actually wire up an LCD screen, but I ran the code.] It takes 24 milliseconds to initialise the LCD screen, and 55 milliseconds to transmit the two lines of text to the LCD screen, including loading the values onto the pins. Loading the 4 bits onto the pins and toggling pin 12 takes 1 millisecond. My mind is aglow with whirling, transient nodes of thought careening through a cosmic vapor of invention. Hedley Lamarr, Blazing Saddles (1974) |
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muddy0409 Senior Member Joined: 15/06/2011 Location: AustraliaPosts: 125 |
I have a possible application for this unit, however it requires reading a parallel 4 bit nibble to work, 18 times in reasonably quick succession. This may be possible if I map the 4 input lines to sucessive port pins, but I haven't stydied this yet. Don't poo poo conspiracy theories. Remember that everything ever discovered started somewhere as a theory. |
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