Why is so8 test clip causing read errors with 93C56 eeprom (TL866 programmer)?

Discussion in 'Embedded Systems and Microcontrollers' started by cds333, Jan 10, 2016.

  1. cds333

    Thread Starter Member

    Nov 5, 2007
    I am trying to read an Atmel 93C56B eeprom, so8 surface mount package, with this programmer. When using the so8 adapter in the zif socket it works perfectly. However when I use the test clip, it is giving me read errors on every other bit. The errors are consistent and seem to happen with every bit value except FFFF.

    The test clip works fine when writing data also.

    This is what it should look like:

    This is what it looks like when using the clip:

    And here are a few other bit values, (spliced together to save space)

    In every case (except FFFF), the even numbered bits (0,2,4,...) return the correct value, and the odd ones are wrong.

    I am guessing this has to do with the length of the leads, however I even shortened the lead length by 75% and still have this problem. I have also tried 8dip versions of this eeprom in this same programmer and they never give errors so I must assume it is the clip. I have checked the pins of the clip and they are all correct (and if they weren't it shouldn't be able to write to the eeprom)

    If this were a serial port I might try slowing down the bitrate, but this programmer seems to have no settings at all.

    The reviews for this clip dont mention this problem, and it is sold by the same company that sells the programmer.

    Btw the chip is not soldered to anything, it is attached only to the test clip

    Chinese manufacturer of the programmer: http://www.autoelectric.cn/EN/TL866_MAIN.html

    Any insights greatly appreciated!
  2. KJ6EAD

    Senior Member

    Apr 30, 2011
    My best guess is a flaky connection on one of the wire to pin connections at the back end of the clip.
  3. cds333

    Thread Starter Member

    Nov 5, 2007
    It seems to only be doing it with the one AT93C56B-SSHM-B-ND eeprom. (Two different of those same chip were tested) However Using another 93c56 from another manufacturer gives no similar error.

    I would still like to know why it is able to write but not read?

    Please do not take anything for granted, the answer maybe dead simple but I'm just not seeing it.