Bs1 pwm
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Posts: 46,084
Stampers,
How have you found the PWM output on the BS1?
How accurate is it?
We have an app weher we need to generate 0-5v in 255 steps do PWM seems to
fit the bill perfectly. We will monitor that volatge with an input that has a
100k input impedance. That should not apply to much of a load I would hope!
Stocky
[noparse][[/noparse]Non-text portions of this message have been removed]
How have you found the PWM output on the BS1?
How accurate is it?
We have an app weher we need to generate 0-5v in 255 steps do PWM seems to
fit the bill perfectly. We will monitor that volatge with an input that has a
100k input impedance. That should not apply to much of a load I would hope!
Stocky
[noparse][[/noparse]Non-text portions of this message have been removed]
Comments
Further to the message below, we have tried it but it seems to vary, as in
the steps dont seem to be the same, eg for exampel if a step is supposed to be
0.0196v the steps don't follow the pattern of: 0.0196, 0.0392, 0.0588, etc
Is this just an error/factor of the PWM command?
Original Message
From: Tim Stockman, STOCKMAN ELECTRONICS
To: basicstamps@yahoogroups.com
Sent: Wednesday, October 17, 2001 9:15 PM
Subject: BS1 PWM
Stampers,
How have you found the PWM output on the BS1?
How accurate is it?
We have an app where we need to generate 0-5v in 255 steps do PWM seems to
fit the bill perfectly. We will monitor that volatge with an input that has a
100k input impedance. That should not apply to much of a load I would hope!
Stocky
[noparse][[/noparse]Non-text portions of this message have been removed]
I don't know which stamp you are using, but most likely you are seeing
exactly what the BS2's PWM command produces. It is supposed to work
differently from conventional PWM. A rapid sequence of short pulses, some as
short as 4uS are generated that will equal the desired PWM proportion every
millisecond. It can get you to the output level quickly, but won't ever give
you nice, ordered pulses, as you are expecting.
Chris
>
Original Message
> From: Tim Stockman, STOCKMAN ELECTRONICS [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=VCbCIsW6PtY1c8dh0_xXSQrCsSfiJJdBsInISPby8mVucsydCTZH-8ag3ePl5I0BvJT_OSZpny9i_Ksktw]stocky@c...[/url
> Sent: Thursday, October 18, 2001 7:08 AM
> To: basicstamps@yahoogroups.com
> Subject: [noparse][[/noparse]basicstamps] Fw: BS1 PWM
>
>
>
>
>
> This message didn't seem to make it to the list last time.....
>
> Further to the message below, we have tried it but it
> seems to vary, as in the steps dont seem to be the same, eg
> for exampel if a step is supposed to be 0.0196v the steps
> don't follow the pattern of: 0.0196, 0.0392, 0.0588, etc
> Is this just an error/factor of the PWM command?
>
>
Original Message
> From: Tim Stockman, STOCKMAN ELECTRONICS
> To: basicstamps@yahoogroups.com
> Sent: Wednesday, October 17, 2001 9:15 PM
> Subject: BS1 PWM
>
>
> Stampers,
>
> How have you found the PWM output on the BS1?
> How accurate is it?
>
> We have an app where we need to generate 0-5v in 255
> steps do PWM seems to fit the bill perfectly. We will monitor
> that volatge with an input that has a 100k input impedance.
> That should not apply to much of a load I would hope!
>
> Stocky
>
>
>
>
>
> [noparse][[/noparse]Non-text portions of this message have been removed]
>
>
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Are you using an RC/op-amp filtering circuit with the PWM? (BS1
ap-note 15) That is very necessary in order to get even steps. I
don't know what you mean when you say, "We will monitor that volatge
with an input that has a 100k input impedance. That should not apply
to much of a load I would hope!" Yes, too much load if there is not
an op-amp buffer.
See also,
http://www.emesystems.com/BS2PWM.htm
-- regards,
Tracy Allen
electronically monitored ecosystems
mailto:tracy@e...
http://www.emesystems.com
>This message didn't seem to make it to the list last time.....
>
> Further to the message below, we have tried it but it seems to
>vary, as in the steps dont seem to be the same, eg for exampel if a
>step is supposed to be 0.0196v the steps don't follow the pattern
>of: 0.0196, 0.0392, 0.0588, etc
> Is this just an error/factor of the PWM command?
>
>
Original Message
>From: Tim Stockman, STOCKMAN ELECTRONICS
>To: basicstamps@yahoogroups.com
>Sent: Wednesday, October 17, 2001 9:15 PM
>Subject: BS1 PWM
>
>
>Stampers,
>
> How have you found the PWM output on the BS1?
> How accurate is it?
>
> We have an app where we need to generate 0-5v in 255 steps do
>PWM seems to fit the bill perfectly. We will monitor that volatge
>with an input that has a 100k input impedance. That should not apply
>to much of a load I would hope!
>
>Stocky