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Plasmamac

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Joined: 31/01/2019
Location: Germany
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Posted: 11:27pm 30 Jul 2023

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iam curiosity about the delay between the pins bits if i use the port command .
no digital analyzer atm so i ask here .

the user manual say :Set a number of I/O pins (i.e. with one command)

but how simultaneously is it ?
Edited 2023-07-31 09:30 by Plasmamac

Plasma

Mixtel90

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Posted: 06:50am 31 Jul 2023

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I think PORT bits are now effectively written and read as a single word, so it is actually simultaneously. If there is any delay at all it's probably not measurable.

I say this because this isn't a simple IO port based on a flip-flop register on the data bus. Things don't work like that any more. :) It may be that the individual pin registers are controlled one after the other then the whole register is copied to the pads. The end result is the same.

Mick

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Preliminary MMBasic docs & my PCB designs

Volhout
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Joined: 05/03/2018
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Posted: 07:02am 31 Jul 2023

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Plasma,

Less than 4ns (0.000000004 seconds) delay measured between individual pins changing.
For MMBasic you can assume they change simultaneous.
That is why Mick suggested to use the PORT command to drive stepper motors. They change all at the same time.

Volhout
Edited 2023-07-31 17:03 by Volhout

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panky

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Posted: 07:21am 31 Jul 2023

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Using this code on a Picomite running the latest software -

Setpin gp7,dout
Setpin gp13,dout
do
port (gp7,1,gp13,1) = 1
port (gp7,1,gp13,1) = 0
loop

On the oscilloscope, there is no measurable difference (less than 1nS on a 100MHz scope) on the positive transition with up to 30nS of ripple on the high state.
The negative transition has up to 20uS jitter.
The switching frequency in this example is around 14MHz.
D.

... almost all of the Maximites, the MicromMites, the MM Extremes, the ArmMites, the PicoMite and loving it!

Plasmamac

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Posted: 08:55am 31 Jul 2023

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Thx for the test.

Plasma

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