A few questions about schematic

berkeman

Sure, whatever. Real world verusus the lab.

maverick99

Alright, cool. Thx for all the help. I will be sure to post results and pics once I finish it here within a month. That is, if I don't have anymore questions during that time

maverick99

Well I'm back again. Since I have to order parts online, I have to wait a few days to work on the reciever/transmitter circuits. I figure I might as well make the stepper motor circuit while I have this free time. Could anyone supply me with a circuit in which I could do this?

The stepper motor is supposed to sweep 180 deg, back and forth. The first my professor gave me was the L298 Dual Full-Bridge Driver.
http://tinyurl.com/e42un

The other is the L297 Stepper Motor Controller.
http://tinyurl.com/bzokx

Edit: Here is the data sheet for the stepper motor
http://www.jameco.com/wcsstore/Jamec...dDS/213321.pdf

berkeman

You're going to need at least a CPLD or a microcontroller to drive the stepper motor circuit & process the sonar returns. What is your strategy for that part of the circuit?

maverick99

I plan on separating the two circuits. The stepper motor circuit will turn back and forth 180 degrees. Thats all it will do. I will have the transducers hooked up with long wires and mount them to something fairly sturdy to put on the motor to turn.

maverick99

Could anyone supply me with a schematic for the stepper motor with the chips that I was given?

berkeman

The link you supplied for the L297 has an Application Note link underneath it. It looks to be a pretty complete tutorial. Just click through your link and look for the Application Note link:

maverick99

In that pdf files, what is the MCU?

berkeman

Any general purpose microcontroller could be used. That's why I asked earlier in the thread what CPLD or uC you planned on using. You will need at least some logic to provide those control signals to the stepper driver. It would be a good idea to also have limit switches at the ends of your 180 degree travel, to help your uC do some sort of initialization routine after power up or other reset.

You can start off playing with the motor by just using switches to provide the input signals....

maverick99

When testing the motor, do i need any current limiting components?

maverick99

On the schematic that was given, what is the purpose of the 8 diodes? Would rectifier diodes work for the schematic?

berkeman

Look at the currents in figures 15 and 17 for your answer. Any diodes should work as long as they have adequate current and power ratings.

maverick99

Alright cool, sounds good. I tested out the motor and got it working right with just a dip switch. I will need to program a chip to count the way i need it to, too. My question is, do i even need the l297 and l298 in the circuit? Couldn't I just simulate the dip switch counting with the programmable chip and have that going to the motor? If not, then what are the l297 and 298 doing in the circuit?

berkeman

You could probably drive the correct waveforms from your uC into the power transistors that drive the motors -- might even get you extra credit in the project. You need to make the correct waveforms for the stepping and holding currents, but yeah, the uC could do that if you program it right.

Ouabache

If you did want to make a real world design as berkeman suggested, using a voltage regulator to step down a 9v supply to 5v is not hard. On the bench, you could determine how much current is drawn by your design and then decide if a 9v battery could work for the high supply..

Ouabache

How will you mount the transducers so they will be turned by the stepper motor? Will transducers be on the same board as the rest of your circuit? I am trying to get a 3-dimensional idea of your final setup. Are you going to go with a circuit like the minibot one you posted at the end of #11 of this thread?

Ouabache

How about the range of your Ultrasonic Design. The spec for the project is 25feet. Only one of the circuits referenced on this thread are rated for that distance.

SRF04 Ultra Sonic Ranger
max range is 3m (x 3.28 ft/meter) = 9.84 ft
Ultra Sonic Rangemeter
max range 3.6m (x 3.28 ft/meter) = 11.8ft
Sonar Ranging System for Minibot
max range 5-6ft
Ultra-Sonic Ranging Design
max range 10.7m (x 3.28) = 35 ft

If you did go with one of the other designs, is there a way to improve gain of the circuit?
Perhaps use more sensitive transducers?? (see below)
Scientific Technologies, Inc.
Sensors with range 25ft
NEMA6 Acu-trac
Sensors 8m (25ft)