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sattress
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Joined: 13/11/2017
Location: Australia
Posts: 7

Posted: 11:07pm 28 Dec 2017

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First time post in the BackShed

I make sculptures out of junk, making them kinetic and interactive. The Micromites, Nanomites and Picomites have been a revelation and a revolution. Given the demand on pins for A/D lines and PWM outputs in these pieces, I was hoping in the latest refurbishment of a mechanical lyre bird to have each PWM output also available as an A/D input. The micromite manual suggests that using the LOCAL command in a SUB will work. And it does. A hall effect sensor, via a resistance bridge and a diode provides position sense, and when a SUB with a LOCAL SETPIN command is invoked, a PWM output appears on the same pin. But only once. From that point, going back to the sensor part of program, there is a zero input, which continues to alternate with the PWM output, apparently still okay (on an oscilloscope), A restart gives another successful episode of sensing, followed by PWM output, but again only once.

I have no training in any of the skill sets that many BackShed members have. I have tried adding a second LOCAL command as the SUB is about to end (not allowed), I tried GOTO commands but LOCAL is not allowed (?). Any suggestions for what I suspect is a trivial matter, but has got me stumped.

Best

Paul

JohnS
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Joined: 18/11/2011
Location: United Kingdom
Posts: 4044

Posted: 11:29pm 28 Dec 2017

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Posting some code may help.

John

TassyJim

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Joined: 07/08/2011
Location: Australia
Posts: 6283

Posted: 01:37am 29 Dec 2017

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I think you are asking more than was ever anticipated.

Rather than using LOCAL,
You could try a PWM STOP before setting the pin as an input and then setting the PWM again at the end of the SUB

Jim

VK7JH
MMedit

sattress
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Joined: 13/11/2017
Location: Australia
Posts: 7

Posted: 02:35am 29 Dec 2017

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JohnS said Posting some code may help.

John

John
Thank you for help. I hope the following code does not produce too much laughter. This is running on a test rig using a 28pin micromite and only has a single input to pin4
Paul

CPU 48
OPTION EXPLICIT
OPTION AUTORUN ON
DIM AS INTEGER COUNTA
SETPIN 4, AIN

SENSOR:
COUNTA = 0
Do
PAUSE 1
COUNTA = COUNTA + 1
PRINT PIN(4)
PAUSE 1000
IF COUNTA > 5 THEN
COUNTA = 0
MOTOR
END IF
LOOP

SUB MOTOR:
LOCAL SETPIN 4, DOUT
PWM 1, 25, 50
PAUSE 3000
PWM 1, 25, 0
END SUB

sattress
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Joined: 13/11/2017
Location: Australia
Posts: 7

Posted: 02:47am 29 Dec 2017

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TassyJim said I think you are asking more than was ever anticipated.

Rather than using LOCAL,
You could try a PWM STOP before setting the pin as an input and then setting the PWM again at the end of the SUB

Jim

Jim,
'you are asking more than was ever anticipated' is a bit ominous.

With the sculptures I use up the PWM ports quickly, followed soon after by the spare A/D only ports. I have got around this problem by using multiple processors, sometimes many of them. It works, but inter processor communications are very challenging for me and perhaps I can do better by giving ports dual tasks. I shall keep 'ominous' in mind.

I shall give the PWM STOP command a go. Good idea. Very grateful
Paul

sattress
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Joined: 13/11/2017
Location: Australia
Posts: 7

Posted: 05:57am 29 Dec 2017

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sattress said

Jim,
The PWM STOP command improves performance. Without it, when trying to swap between a PWM output and an A/D input, the PWM output occurred when it should but the A/D input seemed to be clamped at 0volts.

With the PWM stop command, the PWM output continues to occur when it should, and now the A/D input is floating free and responding to the sensor properly on the oscilloscope. Unfortunately, while there is no clamp, the A/D looks like it is behaving as a Digital Input rather than an Analogue input as far as the Micromite is concerned. It is producing 1 or 0 at the right time when moving a magnetic slug over the Hall effect sensor. Linking this input to a different PWM output suggests it is digital as there is no fine modulation.

Your 'ominous' has moved from something vague, distant thunder perhaps, to lightning less than a mile away. Any other thoughts? Very grateful for the learning to this point.

Best
Paul

disco4now

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Joined: 18/12/2014
Location: Australia
Posts: 1003

Posted: 06:16am 29 Dec 2017

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Paul,
make sure the
SETPIN 4, AIN
is executed again after the PWM STOP.

I think PWM will set the pin as a output by default, but getting it back to analogue will need SETPIN 4, AIN to be executed each time. It seems to be outside the main loop so would only run once.

regards
Gerry

Latest F4 Latest H7 FotS

sattress
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Joined: 13/11/2017
Location: Australia
Posts: 7

Posted: 06:34am 29 Dec 2017

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disco4now said Paul,
make sure the
SETPIN 4, AIN
is executed again after the PWM STOP.

I think PWM will set the pin as a output by default, but getting it back to analogue will need SETPIN 4, AIN to be executed each time. It seems to be outside the main loop so would only run once.

regards
Gerry

Gerry, Jim and John,
Success. Works like a charm. PWM STOP and a SETPIN 4, AIN are both required.
Many thanks
Paul

Code that works is :
CPU 48
OPTION EXPLICIT
OPTION AUTORUN ON
DIM AS INTEGER COUNTA
SETPIN 4, AIN

SENSOR:
COUNTA = 0
Do
PAUSE 1
COUNTA = COUNTA + 1
PRINT PIN(4)
PAUSE 1000
IF COUNTA > 5 THEN
COUNTA = 0
MOTOR
SETPIN 4, AIN
END IF
LOOP

SUB MOTOR:
SETPIN 4, DOUT
PWM 1, 25, 50
PAUSE 3000
PWM 1, STOP
END SUB

JohnS
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Joined: 18/11/2011
Location: United Kingdom
Posts: 4044

Posted: 07:40am 29 Dec 2017

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Excellent!

(And no-one laughed. They're not likely to do that.)

John

sattress
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Joined: 13/11/2017
Location: Australia
Posts: 7

Posted: 08:18am 29 Dec 2017

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JohnS said Excellent!

(And no-one laughed. They're not likely to do that.)

John

John and others,
A unique experience for me today, and one that I shall treasure. All your help will transform 'Lyre'. I would attach a picture but not sure if it is allowed, or possible. Currently Lyre responds to shadows, or high frequency sounds (air brakes on trucks work well) by head nodding and if pushed, by moving tail over its head. Its PIC was stretched by this but a 28pin micromite, with the tricks I have learnt from the BackShed today will do all of that and much more. The Mite will not have to breath deeply, probably wont get above idling.

Very grateful to everyone.

Paul

Azure

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Joined: 09/11/2017
Location: Australia
Posts: 446

Posted: 08:58am 29 Dec 2017

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Paul

You might want to make things simpler in your code when you need to split a pin between AIN and using it as a PWM output by passing the pin number to the subroutine and changing it to PWM and back to AIN within the subroutine.

You could also pass some of the other parameters like pwm channel#, freq, duty cycle and pause length to make the main code simpler.

Also just a tip to make you code more readable at every nesting level add 2 spaces.

CPU 48
OPTION EXPLICIT
OPTION AUTORUN ON
DIM AS INTEGER COUNTA
SETPIN 4, AIN

SENSOR:
COUNTA = 0
DO
PAUSE 1
COUNTA = COUNTA + 1
PRINT PIN(4)
PAUSE 1000
IF COUNTA > 5 THEN
COUNTA = 0
TEMPPWM(4)
END IF
LOOP

SUB TEMPPWM(NBR%)
SETPIN NBR%, DOUT
PWM 1, 25, 50
PAUSE 3000
PWM 1, STOP
SETPIN NBR%, AIN
END SUB

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