How to connect/use Keypad and LCD Monitor to the PE Kit?
RogerInHawaii
Posts: 87
I've purchased the Parallax Education Kit and have it assembled and running and am going through the various labs.
I also purchased the 4 X 4 Keypad (and associated MEMKey and cable) and the 3.5" LCD Monitor.
But they come with no documentation.
Where can I get documentation on how to connect these two devices to my PE board and to then program them?
I also purchased the 4 X 4 Keypad (and associated MEMKey and cable) and the 3.5" LCD Monitor.
But they come with no documentation.
Where can I get documentation on how to connect these two devices to my PE board and to then program them?
Comments
The LCD monitor just expects standard video. You'll need a 3 or 4 resistor "ladder" attached to a group of 4 I/O pins (starting at a multiple of 4) plus some kind of TV video driver. The Propeller Tool comes with TV.spin and you can use this with either a text driver (TV_Text.spin) or a graphics driver (Graphics.spin). There are demo programs for both that come with the Propeller Tool. Download and use the schematic for the Propeller Demo Board to see how the video output is connected. It uses I/O pins 12-15 for this, but any group of 4 will work. The 4th resistor is used to supply TV audio. I don't think any of the standard I/O drivers have any provisions for audio.
You refer to the "documentation" that is mentioned on the MEMKey product page but that's basically just a 16 page product spec. I suppose if I were an experienced hardware guy I could make sense of it and figure out how it all hooks up myself, but I'm not. The PE Kit is pretty good in being quite explicit as to how everything hooks up, and I was expecting that level of description for the MEMKey and Keypad. But it's not there.
The cable fits perfectly into the back of the keypad, but there are more pins on the back of the MEMKey than there are connectors on the end of the cable. I'm guessing that the cable is intended to connect to pins K0 through K7 on the Memkey, leaving pin K8 not attached to anything. But then, how do I connect the MEMKey to the PE board? There's a separate set of pins on the MEMKey, namely VDD, GND, TM, FM, and KEY. I'd guess that VDD and GND connect to VDD and GND on the PE board, but what do I do with TM, FM, and KEY? And these pins clearly can't just plug in to the PE board, since the other pins/cable would get in the way. Is there another cable or connector I need in order to connect the MEMKey to the PE board?
Please understand that the manufacturer of the product (MEMKey in this case) has made their product compatible with many microcontrollers. Because of this there are no specific instructions on how to connect it to the PE kit. The information needed is there though. The datasheet on our website:
http://www.parallax.com/Portals/0/Downloads/docs/prod/datast/memkey.pdf
…describes the connections for each of these pins on the interface. VDD goes to your power supply. As Mike suggested this should be 3.3V on the Propeller for compatibility. TM and FM are the serial communications lines. As far as which pins these go to on the PE kit, you would really define that by your code. You can use any available I/O lines as long as the serial code you write on the Propeller is set up to use those lines as well. GND should be common. The KEYPRESS line is optional on the Propeller since serial communication could be buffered. On the BASIC Stamp you would use ti to know when to be ready to receive serial data.
On page 4 is the key map. It describes the connections to the header. Since your keypad does not have 5 rows, K8 would not be used. However, you do want to be sure your rows and columns line up properly. Nothing bad will happen if it is backward, however you won’t get the key values you expect. As a note…you could also connect the keypad pins up directly to the Propeller using resistors and scan it without the MEMKey. What the MEMKey does is the overhead of scanning the keypad, debouncing the keys and assigning a key value to it, as well as reducing pin count through the serial interface. I hope this helps. Take care.
▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
Chris Savage
Parallax Engineering
Thank you for the information/
I do understand that the manufacturer of the MEMKey wouldn't include directions on how to connect it to the Parallax products, since their product is designed for a multitude of applications. But I had hoped that Parallax would either include in the shipped product, or at least have a downloadable instruction sheet on how to actually connect it and use it with your products. I've been going through the Propeller Education Kit and have been quite impressed with the clarity and comprehensiveness of the documentation. It is rare that you see such a professionally produced education/instruction manual. So, I had hoped that the other products that you sell, intended for interfacing with your microcontrollers, would have similar documentation.
- Roger
I apologize that we don’t have detailed information on such a subject. We don’t often add to manufacturer documentation as it is required to provide enough information to facilitate use with our products. Hopefully the information I provided will assist you. If there is additional information please feel free to follow up in this thread and ask and I will do what I can. Take care.
▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
Chris Savage
Parallax Engineering
I haven't had time to finished the writeup for this code, but here's a simple
combination lock (demo) that uses Beau's 4x4 code for the keypad and TV out.
{So you'll be able to play with both devices.}
1.. Build yourself a little three resistor DAC (like Mike indicated) for the video out.
(There's more information on video in the Cookbook link below, look for "reversible video card".)
2... Plug an LED into P8 (with a resistor) (This is for effect. arm & disarm)
3... Plug your 4x4 keyboard into P0..P7 (see the top of the Spin code for a diagram.)
The "combination lock" code is well documented, so you should be able to see how it works.
If you are getting stuck report back.
OBC
▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
New to the Propeller?
Check out: Protoboard Introduction , Propeller Cookbook 1.4 & Software Index
Updates to the Cookbook are now posted to: Propeller.warrantyvoid.us
Got an SD card connected? - PropDOS
I scanned this thread very quickly... so if this is redundant or erroneous, please excuse.
Actually, documentation is one of those things that Parallax really does well. You wouldn't know it from reading all the flames in the forum, but it is really, really great.
Almost always, anything offered in the Store is well enough documented to be used with the Prop. The only issue: where is the documentation? If it isn't on the product page.. it is somewhere, be assured of that.
Usually, the way this works for me (a rudimentary hacker) is to find something I want... Then, like you, I read the links on the product page... then I go to the OBEX to see what all of that means in terms of actual implementation.
If I am still in a fog, I go to this forum and do a search... from multiple directions. If I fail there... then I just ask the question, without any sense of modesty[noparse]:)[/noparse]
Beau wrote and documented an object for this ... (At least I think this is the same unit)
http://obex.parallax.com/objects/279/
Post Edited (rjo_) : 2/20/2009 8:40:59 PM GMT