I have a 7109 12 bit uP A/D converter and I want to convert its binary output to BCD to drive a 7911 4 digit MUX input BCD lcd driver. Does anybody have or know of any program or application or any other means of producing the eprom code???

A similar project is this old thread, but the method of producing eprom code is crude.

Thanks in advance

 

If your conversion involves an EPROM, using the binary value as the address to produce the BCD as an output is about the only way to do it. What part of the process do you find crude?

 

The production of ERPOM data by writing software for PIC is what I call crude (read PLEASE READ file). This is the reason I am asking for a more automated and probably generalized way of producing data. What if some address or output lines are transposed?? this is where things are becoming very difficult. I assume that someone somewhere has coded a similar application (or maybe an excel WS) that might be appropriate. Thanks for the interest

 

Yes I know how to make it by hand and that is I call crude to program all cells of a 32k EPROM.

Actually, 32k won't be enough bits. You'll need more like 64k bits.

This is the reason I am asking for a more automated and probably generalized way of producing data. What if some address or output lines are transposed?? this is where things are becoming very difficult. I assume that someone somewhere has coded a similar application. Thanks for the interest

You can always erase the EPROM and start over.

Or you can wire-wrap the prototype board, which will make it easy to swap data and address lines around, should the need arise.

Or you can triple-check your data and wiring before you program it.

 

Alright SgtWookie then I have to disclose my secret: I have a ready made digital thermometer using mentioned chips, that displays in the limited range of 30.00 to 38.00 degrees. Lower than 30 displays LO and higher than 38 displays HI. Also EPROM A0 pin seems to be unconnected! EPROM A1 to A11 are connected to bits 2 to 12 of the 7109 ADC. I want to reprogram the EPROM to display the full range, possibly negative values also. Hence all the difficulties I mentioned above. I will try the manual method and keep informing the progress. Thank you

 

This is just a suggestion. I am not sure it may help you any. At this this site http://www.htsoft.com/products/compilers/piccpro-get.php#downloads you can download C tools for your PIC uC. If you used this and floating point notation. You do not need to make a huge lookup table. Also since you are measuring temperature you may drop some of the least significant bit from the AD conversion. You do not need very accurate temperature. 1 decimal should do. Say if you want a temperature range equal to 0-100 degree Celsius. With 9 bit you will have a resolution equal to 0.1953125 Celsius

 

Hi.

I did this and it is on this forum in a post uploaded on 05-08-2007.

This will convert binary and display the the result on a 4 digit multiplexed LED display.

If you need to build it, all the details are there. If you need the EPROM programmed, just e-mail me your address and I will do it and put it in the post.

Daniel.

 

I thank everybody for the tips. Back to my "problem" I noticed that the pcb had a patent number printed. A google search showed that this patent relates to an instrument using inexpensive non linear thermistor to measure temperature to .01 degree accuracy, by linearizing the results. EPROM gets binary input from A/D and gives corrected (linearized) BCD data to LCD driver. Therefore the output data are NOT directly related to input data. I will try anyway to cut the min/max limits and display the full range.

If you are interested in the patent details here is a link.

 

Every composition of materials in thermistors has a characteristic response curve. You can obtain the curve from the manufacturer that applies to any device and use it to generate the corrected readings in the EPROM table.

 

I have two solutions:

1. Download Python and write a script to output a file in any convenient format for a programmer.
2. Download Visual Studio 2008 Express and so the same

Both are free and the investment of time if you do not know C or Python will be repaid going forward on other projects.

 

Very likely beyond the above limits the thermometer gives so bad results that will be useless and dangerous to believe (especially if it is used for body measurements). That the reason why the manufacturer is not displaying numbers in the non linear region.

Alberto

The linearizion of the thermistor curve is done in the ERPOM, which reads the resistor values from the A/D and translates to temperature. The EPROM is programmed by solving the resistance - temperature equation. See patent link in my previous post. The limited range is imposed by the application which was of medical nature (measured the temperature of a water bath in a in vitro diagnostic machine).