The Stamp can do pretty well controlling 2 or maybe 3 servos, but it makes the code kind of convoluted because a pulse has to be sent to each servo at least every 20ms. The PWMPAL can generate the pulses independently in a "set and forget" manner for up to 4 servos. It can also be configured to produce PWM for driving a DC motor (or up to 4 of them). You'll need a motor driver to handle the current, but you could use an IC version like the L293 which would also allow you to change direction as well as control the speed.
It's like asking what's the difference between an apple and a pear. They have a lot of things in common, but they're different.
The servopal is a cheap, simple device for taking over the task of periodically issuing servo control pulses.
The pwmpal also can take over the task of periodically issuing servo control pulses, but differentlly. It can handle up to 4 servos.
It can also control DC motors with a suitable driver. It can also independently count input pulses
When the Stamp is counting pulses, it can't do anything else. If the PWMPAL is counting pulses, the Stamp can be doing something else like transmitting data or controlling a servo motor or reading some kind of sensor.
I'm sure a PWMPAL can be used for all sorts of things. Why do you ask?
well, i have the servopal and the pwmpal, and i am using the servo pal to control the servos that run the treads on my boebot. i would like to find an application for the pwmpal. I also have an the 2125 accelerometer, a sensirion temp/hum, rf reciever and transmitter(parallax), and bread board appmod -- it would be interesting if i could get them to run in conjunction.
One of my projects is called ABBot (Advanced Boe Bot) and uses the accelerometer and the sensirion temperature/humidity sensor, together with many other components (LCD, TTS, Ping, etc.).
Okay....I got everything connected according to the schematics. I tried loading the code...and what I am getting is feedback from the CNS. The emic is saying: "No connection." Also, the LCD I have which is 4 by 20 has an arrow on it and the letter n. I'm assuming i am missing a few steps here. Anyone got any advice on how I should proceed?
First thing is to make a schematic of what you actually have (not what it's supposed to be). Trace through the actual wires to make the schematic. Then attach the schematic and a copy of your source code to your reply using the forum attachment manager (using the Post Reply button).
Without a lot more information, it's really impossible to give you anything more than very general and not very useful advice.
If you are using my ABBot project and the Emic says "No connection", it means that the first Board (CNS) is calling the second board (PNS), but this one does not answer.
Please check that every connection is exactly like in my diagrams. Especially the connection between the two boards must be done as shown at page 9 of my documentation (P0 of CNS connected to P0 of PNS and both connected to a common ground through a 10 kohm resistor, P1 of CNS connected to P1 of PNS through a 1Kohm resistor).
The ABBot shown in the YouTube videos is based exactly on the programs and the circuits posted here. So the problem is probably in some wrong connection or maybe in low power batteries.
ryan.sessman
Posts: 12
Comments
The Stamp can do pretty well controlling 2 or maybe 3 servos, but it makes the code kind of convoluted because a pulse has to be sent to each servo at least every 20ms. The PWMPAL can generate the pulses independently in a "set and forget" manner for up to 4 servos. It can also be configured to produce PWM for driving a DC motor (or up to 4 of them). You'll need a motor driver to handle the current, but you could use an IC version like the L293 which would also allow you to change direction as well as control the speed.
The servopal is a cheap, simple device for taking over the task of periodically issuing servo control pulses.
The pwmpal also can take over the task of periodically issuing servo control pulses, but differentlly. It can handle up to 4 servos.
It can also control DC motors with a suitable driver. It can also independently count input pulses
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Jessica Uelmen
Education Department
Parallax, Inc.
I'm sure a PWMPAL can be used for all sorts of things. Why do you ask?
You might use it as a reference for your project:
http://forums.parallax.com/showthread.php?p=783408
Without a lot more information, it's really impossible to give you anything more than very general and not very useful advice.
Please check that every connection is exactly like in my diagrams. Especially the connection between the two boards must be done as shown at page 9 of my documentation (P0 of CNS connected to P0 of PNS and both connected to a common ground through a 10 kohm resistor, P1 of CNS connected to P1 of PNS through a 1Kohm resistor).
The ABBot shown in the YouTube videos is based exactly on the programs and the circuits posted here. So the problem is probably in some wrong connection or maybe in low power batteries.