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BS2p and the DS2450 — Parallax Forums

BS2p and the DS2450

DiscoveryDiscovery Posts: 606
in BASIC Stamp
Hi,
Can the BS2p properly setup the DS2450 ADC for 4 channel operation, no alarms, 12 or 16 bit precision using PBasic?
When using the OWIN command only the high Byte has a voltage reading from 0.0 to about 2 volts. An input voltage larger than about 2 volts generates a 0.0 result.
Writing data to the memory for controlling the DS2450 is similar to writing to oblivion.
Sincerely,
Discovery

Comments

  • tomcrawfordtomcrawford Posts: 1,129
    If I Google "Parallax DS2450", the very first non-paid hit is a pointer to "Dallas DS2450 sample code" in the BASIC Stamp forum.
  • DiscoveryDiscovery Posts: 606
    I did the Google and pulled up the "Dallas DS2450 sample code.
    This code was written into the BS2p and executed.
    A 2.500 volt dc input was applied to "D" from a voltage divider potentiomoter.
    The DEBUG wrote 5000 mv. 
    DEBUGGing the inp(0) and the inp(1) showed
    inp(0) = 0000inp(1) = 0250
    The volt equation simply multiplies the inp(1) most significant Byte by two.
    Twelve bits are not used...do you know why? Is there any way to get this DS2450 to output anything but the most significant Byte?
    Sincerely,
    Discovery
  • tomcrawfordtomcrawford Posts: 1,129
    You are probably going to have to study the data sheet.  
    Also, in the Dallas DS2450 Sample Code note, I saw a reference to a Nuts and Volts article.  You might look that up.  But the data sheet is just about always the "go-to" place to learn about an IC.
  • DiscoveryDiscovery Posts: 606
    I have worked that datasheet for months with no success. Someone wrote that the chip is defective from birth and cannot ever output anything other than one Byte.
    I am hoping that someone is clever enought and knows enough about the internals to find a way around the datasheet and get it to function properly.
    I remember some years ago meeting a design engineer who retired from Texas Instruments but was a key player in the development of RISC. There was an application that needed to use algorithms and additional speed that could be attained from commercial RISC but one had to know how to get at the internal registers and gates. This he was able to do and boot strapped a new industry.
    Is there anyone out there who can perform this task?
    Discovery
  • tomcrawfordtomcrawford Posts: 1,129
    Despite the part is obsolete or special order only in disti, I do not believe Maxim released a braindead IC.
    Do you have a couple of pieces mounted on DIP adapters you would be willing to send me?

    tc
  • DiscoveryDiscovery Posts: 606
    I have about 23 of these devices and none of them are mounted except surface mounted on production sensors. They all perform exactly the same. 
    Over the last few days I read several comments from others who found the same problem. The correct code is sent to the DS2450 for full 16-bit operation but only the upper byte contains the reading. If I send code that is not called for...just shooting in the dark, I can get output on both bytes but the output has nothing to do with the measurement.
    At this point, I can do no better than 8-bits on my sensors.
    Discovery
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