Peter Anderson HomeBrew kit & Board of education woes.
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Posts: 46,084
HI all: I have one of the Peter Anderson Home brew kits, as well as a
parallax BS2 board of education. Mr Anderson is apparently out of town
currently, so I am asking my questions here. The homebrew kit uses the 24
pin Pbasic interpretor chip, max239 serial driver, and the 2K EEprom from
parallax.
I built a printed circuit board for the Home brew kit, and have not had
problems with the design before now. But last night I tried driving a servo
for the first time. DOH
Using the board of education, I can drive Servos, with no problem. However
on the Home brew kit, my servos will not work. The servos either barely
turn, or sit and chatter. On the Homebrew kit, changing pulsout values for
the servos makes no differance at all.
I am using the exact same code between the board of education, and the
homebrew kit.
I have modified my servos for continuous rotation, and a pulsout value of
750 is centered, or no rotation.
I also have just realized that on the board of education, when I drive a
peizo speaker, I may hook 1 lead of the speaker to either ground, or to +5v
and I will get a sound output. But on the Homebrew kit. I can ONLY hook the
speaker to +5V. Connecting the peizo speaker to ground, I only get a click
sound one time. ( I lost hair over this also)
I do not think the homebrew circuit or its chips are bad. I can output
speaker sounds( connected to +5V) I can flash an LED, I can input switch
signals, and read my IR inputs. I also can drive an LCD display, so I know
the stamp chips are working on the homebrew kit. I of course can program the
homebrew kit thru the serial cable, so presume everything is good in that
respect.
I cannot understand why I cannot drive servos, yet everything else seems to
be working on the homebrew kit. Could I have some stray signals, or wierd
capacitance build up, causing the pulsout commands to go astray? I have my
16 I/O pins within 1/8" of the interpretor chip, so cant believe I am
picking up any stray signals on the outputs.
I did check the homebrew pin outputs when driving the servo with a logic
probe. I do see some sort of a pulsed output. The high/low/pulse light's all
illuminate on my logic probe. The parallax boebot manaul shows a 10K
resisitor across the output pin to ground, for driving servos. I tried that
also, but no luck.
I have checked for +5 volts on all chips, also double and triple checked my
circuit and the ground paths. I dont see where I have a voltage problem at all.
I also used a LM2940 voltage regulator, and have a 3300 Uf capacitor across
my power lands on the circuit board.
The homebrew kit had a nice circuit design with capacitors and such, I cant
believe there is a problem there either?
It is interesting to note, that pulsout is flooey, and also the speaker
output is differant then on the board of education. Maybe the homebrew
Pbasic interpretor chip has weak outputs? I have tried servo, and speaker
output on various differant pins, and did not see any change. I have read
that sometimes a pin will go bad on the stamps.
I really like the homebrew kit, and had planned to use many of them in the
future. That is why I went to the trouble of making a PCB.
Any advice would be appreciated.
Sincerely
Kerry
Admin@M...
WWW server hosting [url=Http://mntnweb.com]Http://mntnweb.com[/url]
Kerry Barlow
p.o. box 21
kirkwood ny
13795
parallax BS2 board of education. Mr Anderson is apparently out of town
currently, so I am asking my questions here. The homebrew kit uses the 24
pin Pbasic interpretor chip, max239 serial driver, and the 2K EEprom from
parallax.
I built a printed circuit board for the Home brew kit, and have not had
problems with the design before now. But last night I tried driving a servo
for the first time. DOH
Using the board of education, I can drive Servos, with no problem. However
on the Home brew kit, my servos will not work. The servos either barely
turn, or sit and chatter. On the Homebrew kit, changing pulsout values for
the servos makes no differance at all.
I am using the exact same code between the board of education, and the
homebrew kit.
I have modified my servos for continuous rotation, and a pulsout value of
750 is centered, or no rotation.
I also have just realized that on the board of education, when I drive a
peizo speaker, I may hook 1 lead of the speaker to either ground, or to +5v
and I will get a sound output. But on the Homebrew kit. I can ONLY hook the
speaker to +5V. Connecting the peizo speaker to ground, I only get a click
sound one time. ( I lost hair over this also)
I do not think the homebrew circuit or its chips are bad. I can output
speaker sounds( connected to +5V) I can flash an LED, I can input switch
signals, and read my IR inputs. I also can drive an LCD display, so I know
the stamp chips are working on the homebrew kit. I of course can program the
homebrew kit thru the serial cable, so presume everything is good in that
respect.
I cannot understand why I cannot drive servos, yet everything else seems to
be working on the homebrew kit. Could I have some stray signals, or wierd
capacitance build up, causing the pulsout commands to go astray? I have my
16 I/O pins within 1/8" of the interpretor chip, so cant believe I am
picking up any stray signals on the outputs.
I did check the homebrew pin outputs when driving the servo with a logic
probe. I do see some sort of a pulsed output. The high/low/pulse light's all
illuminate on my logic probe. The parallax boebot manaul shows a 10K
resisitor across the output pin to ground, for driving servos. I tried that
also, but no luck.
I have checked for +5 volts on all chips, also double and triple checked my
circuit and the ground paths. I dont see where I have a voltage problem at all.
I also used a LM2940 voltage regulator, and have a 3300 Uf capacitor across
my power lands on the circuit board.
The homebrew kit had a nice circuit design with capacitors and such, I cant
believe there is a problem there either?
It is interesting to note, that pulsout is flooey, and also the speaker
output is differant then on the board of education. Maybe the homebrew
Pbasic interpretor chip has weak outputs? I have tried servo, and speaker
output on various differant pins, and did not see any change. I have read
that sometimes a pin will go bad on the stamps.
I really like the homebrew kit, and had planned to use many of them in the
future. That is why I went to the trouble of making a PCB.
Any advice would be appreciated.
Sincerely
Kerry
Admin@M...
WWW server hosting [url=Http://mntnweb.com]Http://mntnweb.com[/url]
Kerry Barlow
p.o. box 21
kirkwood ny
13795
Comments
any and all ideas. I have tottaly exhausted my ability to solve this problem :-(
I apologize for the long letter.
I have one of the Peter Anderson Home brew kits, as well as a parallax BS2
board of education. Mr Anderson is apparently out of town currently, so I am
asking my questions here. The homebrew kit uses the 24 pin Pbasic
interpretor chip, max239 serial driver, and the 2K EEprom from parallax.
I built a printed circuit board for the Home brew kit, and have not had
problems with the design before now. But last night I tried driving a servo
for the first time.
Using the board of education, I can drive Servos, with no problem. However
on the Home brew kit, my servos will not work. The servos either barely
turn, or sit and chatter. On the Homebrew kit, changing pulsout values for
the servos makes no differance at all.
I am using the exact same code between the board of education, and the
homebrew kit.
I have modified my servos for continuous rotation, and a pulsout value of
750 is centered, or no rotation.
I also have just realized that on the board of education, when I drive a
peizo speaker, I may hook 1 lead of the speaker to either ground, or to +5v
and I will get a sound output. But on the Homebrew kit. I can ONLY hook the
speaker to +5V. Connecting the peizo speaker to ground, I only get a click
sound one time.
I do not think the homebrew circuit or its chips are bad. I can output
speaker sounds( connected to +5V) I can flash an LED, I can input switch
signals, and read my IR inputs. I also can drive an LCD display, so I know
the stamp chips are working on the homebrew kit. I of course can program the
homebrew kit thru the serial cable, so presume everything is good in that
respect.
Could I have some stray signals, or wierd capacitance build up, causing the
pulsout commands to go astray? I have my 16 I/O pins within 1/8" of the
interpretor chip, so can't believe I am picking up any stray signals on the
outputs.
I did check the homebrew pin outputs when driving the servo with a logic
probe. I do see some sort of a pulsed output. The high/low/pulse light's all
illuminate on my logic probe. The parallax boebot manaul shows a 10K
resisitor across the output pin to ground, for driving servos. I tried that
also, but no luck.
I have checked for +5 volts on all chips, also double and triple checked my
circuit and the ground paths. I dont see where I have a voltage problem at all.
I also used a LM2940 voltage regulator, and have a 3300 Uf capacitor across
my power lands on the circuit board.
The homebrew kit had a nice circuit design with capacitors and such, I cant
believe there is a problem there either?
It is interesting to note, that pulsout is flooey, and also the speaker
output is differant then on the board of education. Maybe the homebrew
Pbasic interpretor chip has weak outputs? I have tried servo, and speaker
output on various differant pins, and did not see any change. I have read
that sometimes a pin will go bad on the stamps.
I really like the homebrew kit, and had planned to use many of them in the
future. That is why I went to the trouble of making a PCB.
Any advice would be appreciated.
Sincerely
Kerry
Admin@M...
WWW server hosting [url=Http://mntnweb.com]Http://mntnweb.com[/url]
Kerry Barlow
p.o. box 21
kirkwood ny
13795
supplied
from a different place? I looked at the Parallax Board schematic (leaves some
interpretation) but it looks like the servo is powered before the 5 volt
regulator.
It could be that the Anderson board needs the servo's powered from a different
source (could not find it on his site) , they draw more current than you would
think.
my 2 cents worth
Kerry Barlow wrote:
> Hi again: Nobody has any ideas on my Homebrew servo problems?? I am open to
> any and all ideas. I have tottaly exhausted my ability to solve this problem
:-(
> I apologize for the long letter.
> I have one of the Peter Anderson Home brew kits, as well as a parallax BS2
> board of education. Mr Anderson is apparently out of town currently, so I am
> asking my questions here. The homebrew kit uses the 24 pin Pbasic
> interpretor chip, max239 serial driver, and the 2K EEprom from parallax.
> I built a printed circuit board for the Home brew kit, and have not had
> problems with the design before now. But last night I tried driving a servo
> for the first time.
> Using the board of education, I can drive Servos, with no problem. However
> on the Home brew kit, my servos will not work. The servos either barely
> turn, or sit and chatter. On the Homebrew kit, changing pulsout values for
> the servos makes no differance at all.
Even without a scope, using a little creative troubleshooting should help.
You could do a long, slow pulse-pause loop through an LED or piezo that will
tell you if it is functioning at all.
I am not familiar w/ the homebrew kit, or the BOE, but it sounds like you
would want to check for this kind of basic function first.
CL
>
Original Message
> From: Kerry Barlow [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=bz8gjwPJ5Y_myRWlC_9ouVrYraJTJoCP9eFiAf_zi_kh-hhHT2cDX4q7iDNWddzSlSp_ax3ls6Mt]admin@m...[/url
> Sent: Friday, March 23, 2001 1:10 PM
> To: basicstamps@yahoogroups.com
> Subject: [noparse][[/noparse]basicstamps] Peter Anderson HomeBrew kit & Board of
> education
> woes.
>
>
> Hi again: Nobody has any ideas on my Homebrew servo
> problems?? I am open to
> any and all ideas. I have tottaly exhausted my ability to
> solve this problem :-(
> I apologize for the long letter.
> I have one of the Peter Anderson Home brew kits, as well as a
> parallax BS2
> board of education. Mr Anderson is apparently out of town
> currently, so I am
> asking my questions here. The homebrew kit uses the 24 pin Pbasic
> interpretor chip, max239 serial driver, and the 2K EEprom
> from parallax.
> I built a printed circuit board for the Home brew kit, and
> have not had
> problems with the design before now. But last night I tried
> driving a servo
> for the first time.
> Using the board of education, I can drive Servos, with no
> problem. However
> on the Home brew kit, my servos will not work. The servos
> either barely
> turn, or sit and chatter. On the Homebrew kit, changing
> pulsout values for
> the servos makes no differance at all.
> I am using the exact same code between the board of education, and the
> homebrew kit.
> I have modified my servos for continuous rotation, and a
> pulsout value of
> 750 is centered, or no rotation.
> I also have just realized that on the board of education,
> when I drive a
> peizo speaker, I may hook 1 lead of the speaker to either
> ground, or to +5v
> and I will get a sound output. But on the Homebrew kit. I can
> ONLY hook the
> speaker to +5V. Connecting the peizo speaker to ground, I
> only get a click
> sound one time.
> I do not think the homebrew circuit or its chips are bad. I
> can output
> speaker sounds( connected to +5V) I can flash an LED, I can
> input switch
> signals, and read my IR inputs. I also can drive an LCD
> display, so I know
> the stamp chips are working on the homebrew kit. I of course
> can program the
> homebrew kit thru the serial cable, so presume everything is
> good in that
> respect.
> Could I have some stray signals, or wierd capacitance build
> up, causing the
> pulsout commands to go astray? I have my 16 I/O pins within
> 1/8" of the
> interpretor chip, so can't believe I am picking up any stray
> signals on the
> outputs.
> I did check the homebrew pin outputs when driving the servo
> with a logic
> probe. I do see some sort of a pulsed output. The
> high/low/pulse light's all
> illuminate on my logic probe. The parallax boebot manaul shows a 10K
> resisitor across the output pin to ground, for driving
> servos. I tried that
> also, but no luck.
> I have checked for +5 volts on all chips, also double and
> triple checked my
> circuit and the ground paths. I dont see where I have a
> voltage problem at all.
> I also used a LM2940 voltage regulator, and have a 3300 Uf
> capacitor across
> my power lands on the circuit board.
> The homebrew kit had a nice circuit design with capacitors
> and such, I cant
> believe there is a problem there either?
> It is interesting to note, that pulsout is flooey, and also
> the speaker
> output is differant then on the board of education. Maybe the homebrew
> Pbasic interpretor chip has weak outputs? I have tried servo,
> and speaker
> output on various differant pins, and did not see any change.
> I have read
> that sometimes a pin will go bad on the stamps.
> I really like the homebrew kit, and had planned to use many
> of them in the
> future. That is why I went to the trouble of making a PCB.
> Any advice would be appreciated.
>
>
>
>
>
>
> Sincerely
> Kerry
> Admin@M...
> WWW server hosting [url=Http://mntnweb.com]Http://mntnweb.com[/url]
> Kerry Barlow
> p.o. box 21
> kirkwood ny
> 13795
>
>
>
>
>
>
> Your use of Yahoo! Groups is subject to
> http://docs.yahoo.com/info/terms/
>
>
>
I don't know anything about the Pbasic interpretor chip, but I'm wondering
if your problem might be caused by a clock difference. If you're using the
same code between the two systems, and nothing else changed, but the
code doesn't work in the interpretor side, maybe the pulses are so fast
that the servo can't work.
Good luck
Russ
Original Message
From: Kerry Barlow <admin@m...>
To: <basicstamps@yahoogroups.com>
Sent: Friday, March 23, 2001 1:10 PM
Subject: [noparse][[/noparse]basicstamps] Peter Anderson HomeBrew kit & Board of education woes.
| Hi again: Nobody has any ideas on my Homebrew servo problems?? I am open to
| any and all ideas. I have tottaly exhausted my ability to solve this problem
:-(
| I apologize for the long letter.
| I have one of the Peter Anderson Home brew kits, as well as a parallax BS2
| board of education. Mr Anderson is apparently out of town currently, so I am
Reading your message, I think that you don't own an oscilloscope that could help
to solve your problem.
You can get one free oscilloscope emulation at
http://polly.phys.msu.su/~zeld/oscill.html.
To use it, you need a PC with Win95 or later and a sound card.
It is perhaps not as easy or performing that a real scope, but it is free and
uses only 150KB on the PC.
Your problem may be solved by connecting a 1K to 10K resistor between your
output pin and +5V.
This output is probably "open collector".
Regards
ECO
Original Message
From: "Kerry Barlow" <admin@m...>
To: <basicstamps@yahoogroups.com>
Sent: vendredi 23 mars 2001 19:10
Subject: [noparse][[/noparse]basicstamps] Peter Anderson HomeBrew kit & Board of education woes.
> Hi again: Nobody has any ideas on my Homebrew servo problems?? I am open to
> any and all ideas. I have tottaly exhausted my ability to solve this problem
:-(
> I apologize for the long letter.
sent to me, and have had no luck so far. I added the resistor to stamp pin
outputs with no effect. I checked my servo power, and it has a tottaly
seperate +5V lead for the servos, my ground planes are tied together. I
tried seperate outside power source for the servos with no success. I tried
a slow pulsout, and I see where my LED output will glow and has varying
brightness settings. This makes sense to me, and appears like pulsout is
working.
Thank you for the suggestion of a free oscilliscope, I in fact do have an
Oscope, but dont know how to configure it to even know what I am reading [noparse]:([/noparse]
I dont have an owners manual with the scope. I can setup the scope to read
things, but when it comes to actually checking critical timings I dont
really know what to set the sweep times for
my pulsout is 750 centered, times 2 for the stamp, 1500, but 1500 WHAT on
the scope?
THEN what is a good output display and what is a bad one <S>
I have now noticed the following software code ALMOST works.
On the Homebrew kit I can enter the code as follows
run
pulsout 4,800
goto run
and the servo will run in a continuous direction, at a modest speed, however
I cannot enter any other values, and I cannot get the servo to stop
rotation, or to reverse itself.
On the BS2 breadboard I can use the following code, taken from their boebot
manual.
run
for x=1 to 20
pulsout 4,800
pause 20
next
goto run
with this code I can enter any value I wish for the servo pulsout and I can
stop it or reverse it or do whatever I wish. I simply use a variable for the
speed, and change it in my code depending on if I want the robot to go
forward or back.
Could the homebrew kits resonator be bad somehow making the stamp run at
the wrong speed?
Please everyone understand the Homebrew kit is very nice, I just have some
wierd problem thats all <S>
>> Hi again: Nobody has any ideas on my Homebrew servo problems?? I am open to
>> any and all ideas. I have tottaly exhausted my ability to solve this
problem :-(
>> I apologize for the long letter.
>> I have one of the Peter Anderson Home brew kits, as well as a parallax BS2
>> board of education. Mr Anderson is apparently out of town currently, so I am
>> asking my questions here. The homebrew kit uses the 24 pin Pbasic
>> interpretor chip, max239 serial driver, and the 2K EEprom from parallax.
>> I built a printed circuit board for the Home brew kit, and have not had
>> problems with the design before now. But last night I tried driving a servo
>> for the first time.
>> Using the board of education, I can drive Servos, with no problem. However
>> on the Home brew kit, my servos will not work. The servos either barely
>> turn, or sit and chatter. On the Homebrew kit, changing pulsout values for
>> the servos makes no differance at all.
>
>
>
>
>Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
>
>
>
Sincerely
Kerry
Admin@M...
WWW server hosting [url=Http://mntnweb.com]Http://mntnweb.com[/url]
Kerry Barlow
p.o. box 21
kirkwood ny
13795
interesting note, I wonder if it could be related to my problems, even
though I have an original interpretor chip. They state the following
"Parallax, Inc. has tested the new PBASIC Interpreter chip and has found
only one difference; in circuits where the power supply voltage rises or
falls slowly (ie: in circuits with a high capacitance across power and
ground) the Interpreter chip may begin to run at a harmonic frequency lower
than 20 mHz. To resolve this, a 10 kW W resister is required across the
oscillator pins of the PBASIC Interpreter chip to stabilize the clock source"
What is meant by a high capacitance across power and ground? I thought we
were supposed to use something like a 3300 UF capacitor across the power,
This is stated in the board of education manual?? I dont believe my power
rises and falls slowly, theres no reason it should I dont have anything else
on the circuit yet, just the servo.
I am thinking I do have a differant clock frequency on the OEM homebrew kit
then on the BS2P24-IC and that would certainly mess up my pulsout to servo
timings.
If I were to try the resistor, what value would I use? my 20 mhz resonator
uses external capacitors. Thanks again.
Sincerely
Kerry
Admin@M...
WWW server hosting [url=Http://mntnweb.com]Http://mntnweb.com[/url]
Kerry Barlow
p.o. box 21
kirkwood ny
13795
ones, one unit is so many microseconds. On the faster ones, one unit is much
less. Check the Stamp manual for details.
On Futaba 148 servos, they say neutral (center) is 1520 microseconds. this
means you need a positive pulse 0.001520 seconds in length, with a pause of
0.02 seconds in between.
Assuming your scope has 10 divisions horizontally, and you want to view at
least two pulses, you would put the scope on 5 or 10 miliseconds per
division. The vertical setting should be set to 2 volts per division.
Original Message
> Hello all: Thank you to everyone for your help. I have tried all
suggestions
> sent to me, and have had no luck so far. I added the resistor to stamp pin
> outputs with no effect. I checked my servo power, and it has a tottaly
> seperate +5V lead for the servos, my ground planes are tied together. I
> tried seperate outside power source for the servos with no success. I
tried
> a slow pulsout, and I see where my LED output will glow and has varying
> brightness settings. This makes sense to me, and appears like pulsout is
> working.
> Thank you for the suggestion of a free oscilliscope, I in fact do have an
> Oscope, but dont know how to configure it to even know what I am reading
[noparse]:([/noparse]
> I dont have an owners manual with the scope. I can setup the scope to read
> things, but when it comes to actually checking critical timings I dont
> really know what to set the sweep times for
> my pulsout is 750 centered, times 2 for the stamp, 1500, but 1500 WHAT on
> the scope?
> THEN what is a good output display and what is a bad one <S>
> I have now noticed the following software code ALMOST works.
> On the Homebrew kit I can enter the code as follows
> run
> pulsout 4,800
> goto run
> and the servo will run in a continuous direction, at a modest speed,
however
> I cannot enter any other values, and I cannot get the servo to stop
> rotation, or to reverse itself.
>
> On the BS2 breadboard I can use the following code, taken from their
boebot
> manual.
> run
> for x=1 to 20
> pulsout 4,800
> pause 20
> next
> goto run
> with this code I can enter any value I wish for the servo pulsout and I
can
> stop it or reverse it or do whatever I wish. I simply use a variable for
the
> speed, and change it in my code depending on if I want the robot to go
> forward or back.
boards:-) ·I am thinking that should be 10k Ohms which would be the value you
are looking for and considering that there will be little to no current going
thru it a 1/8 or 1/4 watt resistor should be more than adequate.
Regards,
Randy Abernathy
Woodworking Machine Specialist
4626 Old Stilesboro Road NW
Acworth, GA 30101-4066
Phone/Fax: 770-974-5295
E-mail: cnc002@aol.com[/font]