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Emulating the Programming Cable

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  • Emulating the Programming Cable

    OK, I am a noobie and did not order the 4D programming cable with my display, as I read through the lines and misunderstood that a 3.3v USB > Serial cable would be sufficient, and I have one of those which is FTDI:


    A programming cable is at least a week away, and I would like to get started today !

    So I am thinking that there cannot be anything revolutionary that the 4D programming cable can do that I cannot emulate and hence this post.

    I read somewhere that the DTR line cannot be connected directly to the reset, I am guessing that this is probably not due to voltage (my outputs are 3.3V) , but more likely to the reset pulse width ??!

    Having just hooked up the USB cable, and connected to my scope, pressing the open button in the FAT controller, I can see that the DTR line which is used for reset goes low for 1.6 seconds, which seems a little long for the reset which the programming module data sheet says should be several hundred milliseconds, then it goes high again for 600ms then tries again.

    So my thought is to use a R/C and NPN transistor to convert the 1.6ms low pulse to a 300 ms low pulse.

    Has anyone else done this to save me re-inventing the wheel and am I on the right track with my assumptions of the reset pulse timing etc ??

    Any help / suggestions appreciated, as I have the whole of Sunday set aside to get to know this great platform :-)



  • #2

    Not supported - only cable is but

    Page 7 will show how to turn DTR to a reset


    • #3

      Thanks very much, yes that was pretty much what I intended to do, it's working great using BS170, 100nf and 22K.

      Thanks again