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Talk to encoder chip, run program and store data — Parallax Forums

Talk to encoder chip, run program and store data

qxoticqxotic Posts: 47
edited 2009-06-25 20:35 in BASIC Stamp
Looking for guidance on best approach. I have a circuit built using an EDE1144 encoder chip to receive input from a keypad. The board also will accept a signal to turn on a relay controlling an electronic door strike. I can control it with a program written in BASIC on a windows 98 PC. I am now looking to built a stand alone board to take the place of the PC.

Here is what the PC does and the board needs to be capable of.
Receives parallel signal from encoder chip one digit at a time then compares the code to a database. Then if code is good sends signal to relay for door latch. If it is bad sends signal to a different relay operating an error Beep. It logs the time and date and number. Number of codes in database will always be less than 30.

I want to be able to update the program or more likely, the passcode database using a laptop via usb connection.

I know it will need:
data storage
real time clock
be able to process input from encoder chip
usb connection


My question: what is the best combination of STAMP and accessories to build this project?

I am just now getting back to the project, things at work have been very busy until now. Now I have some time to focus on it, get the hardware and get it working. Once I evaluate the advise and choose the hardware I will post in the appropriate forum for help as I go.

Thank you.
Daniel

Comments

  • $WMc%$WMc% Posts: 1,884
    edited 2009-06-25 01:47
    Daniel

    Any of the BS2 stamp can handle this simple task. With one exception, You didn't spec a baud rate. 38Kbaud is pretty much the limit. The BS2s run great @ 19.2Kbaud or slower.

    Password(s) can be stored and changed and compared with little problem.
    A SN74HC165N or something similar can be used to free up some I/O pins. This is a Parallel to serial shift reg.

    You'll need a RTC like the DS1370 or Eq.

    Parallax has a data logger that stores data on a USB thumb drive. This will·handle all of Your time of use and password(s) used etc. issues. simply pullout the thumb drive stick it in a computer and up load the file.


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  • qxoticqxotic Posts: 47
    edited 2009-06-25 20:35
    Thank you for the reply.· I am not sure what you mean for the baud rate?· Using the computer I did not have to specify since I was using the parallel pins of the encoder chip.· It was easier to program that way for me, but if I had to the encoder chip does transmit serial also at either 2400 or 9600.

    Currently, the computer (which the Stamp will be replacing) uses 8 pins to operate everything.· The time chip I was looking at originally is the DS1302 which would require 3 pins and ground.·

    I am not sure the best way to make the Stamp program available through USB or how many pins that will take?· If I get a stamp with enough memory, it may have enough to hold my program and history, or I may need to add a memory chip.· The data file will be pretty small.· The password code list will be pretty short also so for now I plan to just list that in the programming and edit it there. (I will be the only one dealing with the program).

    I found some great help in the Nuts and Volts for the programming code.· Reading from the encoder chip for me will be the same as their example.· Other than that I'll have to figure out the programming to write to data storage and get the time and date from the time chip.

    Thank you,

    Daniel
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