View Full Version : Clock for use as controler

11-10-2011, 09:15 PM
Iíve been learning the propeller off and on for a while now.
I want to make a clock with an output to turn a relay on or off. I want to be able to set an on and off time, and display it, and the time on an LCD.
Iím wondering if anyone has any modules that may work, if not, I guess Iíll start working from scratch.

11-11-2011, 02:04 PM
Check out the OBJECT EXCHANGE for clock and display objects. Otherwise you'll have to put in some work, people want to see a little effort before helping out. :smile:

Mike Green
11-11-2011, 02:13 PM
A lot depends on how you want to set the on and off time, how you want to display the time, and what kind of LCD you want to use. A lot of the examples for the Basic Stamp can also be used with the Propeller with minor changes (like the use of 3.3V rather than 5V and changes in resistor values because of the voltage difference). Look at the Nuts and Volts columns for example ... click on the Resources tab on the main Parallax webpage and you'll see the link to the Nuts and Volts index. Column #6 discusses how to control relays from a Stamp, but it applies to the Propeller as well. For low power switching, I've used a reed relay tied directly to a Propeller I/O pin. There are a few on the market with 3V coils and coil currents on the order of 20mA. You just need a protective diode (like a 1N914) across the coil as shown in Column #6.

There are all sorts of LCD modules. Parallax sells some. Scott Edwards Electronics and Matrix Orbital make and sell lots of them. Some of them include interfaces for 4 x 4 keypads.

11-12-2011, 01:03 PM
Thank you Bits, for your reply. I think you may have misconstrued my request. I was asking if anyone knew of any modules that may work with my project. You assumed, incorrectly, I did no work on this project, when the exact opposite is true. I was not asking you to design a project for me. I’ve been a digital designer since 1978 and have worked on many projects. I’m not afraid of work. In my experience I found that it is not wise to reinvent the wheel several time, rather to build on experience, and go forward. Thank you, again, for putting forth the effort, and rendering your reply.

11-12-2011, 01:03 PM
Thank you, Mike, for your informative, and assiduous reply, it was most helpful, and I will do as you suggested. You provided the kind of information I was seeking.

11-12-2011, 01:43 PM
... misconstrued my request. ... You assumed, incorrectly,...

Hi Greg

Welcome to the forums. If I may critique your request:

There is not enough information to make assumptions about you skill level, past work, or fears. You did not provide enough information to get a different answer. Both Bits and Mike gave answers appropriate to your request, Mike has 18,000 more posts experience answering the question "What should I use?". This question could bear more detail.

relay - 5v 1A or 120V AC mains? How often will it switch?
time - try to track it yourself in software of use component like DS1302? What is your required response window, minutes or microseconds?
LCD - four digits only (HH:MM) or a 20x4 characters?
User input - one or two buttoms, or via connection to a PC via serial, etc? What will the user provide to the system as input, and how often?
And any other details that are critical....

Any hints to specifics for any of these points would allow folks to point you to different hardware and software modules, and attract responses from folks that have used them.
If you can't say what you want, you might have a harder time getting it. ;)

Even on the prop, requirements and planning are the most critical part of a project, each minute spent planning saves hours of debugging and rework.

Duane Degn
11-13-2011, 12:06 AM
I've use relays like these (http://www.sparkfun.com/products/10924)with the Prop many times.

They need a transistor to drive the coil from a Prop.

I use a 3N4124 to drive the coil. One end of the coil connects with 5V the other end is connected to the transistor. A flyback diode goes across the coil. I use a 470 ohm resistor on the base of the transistor (between the Prop and the transistor).

I'm guessing there are lots of transistors that could do this.

I linked to a relay at Sparkfun. I've used the Sparkfun relay but I believe the same relays are available (and less expensive) at Digi-Key.

I've also used the Prop with these solid state relays (http://www.mpja.com/40A-480VAC-SOLID-STATE-RELAY-UL/productinfo/17157+RL/). The Prop can control the SSR without a transistor.


11-14-2011, 01:36 AM
Sorry, it was not appropriate to reply “you'll have to put in some work, people want to see a little effort before helping out. THAT is not helpful. Mikes answer was not only helpful, but solved the problem for me. Thank you for your help.