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using alternative serial port connection — Parallax Forums

using alternative serial port connection

dgablerdgabler Posts: 7
edited 2007-12-12 04:48 in Propeller 1
I built the alternative serial port connection but I can not seem to program my propeller through the propeller tool. I specifically I have this:
Alt Ser Port Con as shown in the datasheet connected to a usb com port.
ground from that (p5) is connected to ground on the propeller chip board.
I am leeching 3.3v off of a lm2937et that is also powering my prop chip. so the 2937 is powering my prop chip and the ASPC.

I tell Propeller tool to identify hardware it scans com8 but does not see the chip. Do I need to do anything special? I have checked my breadboard a few times to make sure my alt connection was correct.

Comments

  • RaymanRayman Posts: 14,793
    edited 2007-12-11 11:38
    make sure you have the RES\ connection hooked up... This is the signal to the Prop to identify itself...
  • Ron SutcliffeRon Sutcliffe Posts: 420
    edited 2007-12-11 11:46
    Hi dgabler
    I am very new to Prop, but I think Page 18 of the manual is worth another look.
    If I am wrong then I will have learnt something

    ron

    Introducing the Propeller Chip
    Page 18 · Propeller Manual v1.0
    Boot Up Procedure


    a. Detects communication from a host, such as a PC, on pins P30 and P31. If
    communication from a host is detected, the Boot Loader converses with the
    host to identify the Propeller chip and possibly download a program into
    Main RAM and optionally into an external 32 KB EEPROM.
  • Ron SutcliffeRon Sutcliffe Posts: 420
    edited 2007-12-11 12:29
    Hi dgabler
    Back in my box...Alternative as shown on data sheet....not alternative as in pins!
  • dgablerdgabler Posts: 7
    edited 2007-12-11 20:10
    Yes I have the RES connected to pin 4 and all components as shown. All pins are connected up as they should be... My biggest question is: do you need to do anything different to tell the IDE that I am not using a prop plug?

    It possibly seems that one can not use an usb-com port adapter with this alternative wiring
  • QuattroRS4QuattroRS4 Posts: 916
    edited 2007-12-11 20:16
    dgabler,
    You do not need to do anything different to tell the IDE that its an alternative connection ...

    The alternative works without issue with any USB to serial devices I have used ..
    when you say alternative is that with the transistor circuit or using a circuit with an ST3232 IC or equivalent·?

    Regards,
    John

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    'Necessity is the mother of invention'

    Post Edited (QuattroRS4) : 12/12/2007 1:26:22 AM GMT
  • RaymanRayman Posts: 14,793
    edited 2007-12-11 20:23
    One thing that has helped connection problems is to turn off the "FIFO buffers" on your serial port. But, I don't know if that will help if it won't even identify...
  • QuattroRS4QuattroRS4 Posts: 916
    edited 2007-12-11 20:44
    If it is the multiple transistor version ..
    There was some talk a while back that C1 would be either a 10nF or 0.1uf capacitor

    Read this thread ..
    http://forums.parallax.com/showthread.php?p=585009

    also Elektor did a variant of this some time back ..
    www.elektor-electronics.co.uk/magazines/2007/july-august/serial-interface-for-the-propeller.197581.lynkx

    Hope it helps ..

    Regards,
    John Twomey

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    'Necessity is the mother of invention'

    Post Edited (QuattroRS4) : 12/12/2007 1:26:00 AM GMT
    tran.JPG
    581 x 364 - 23K
  • dgablerdgabler Posts: 7
    edited 2007-12-11 21:11
    I am using the transistor circuit described in section 2.3.3 of the datasheet, http://parallax.com/Portals/0/Downloads/docs/prod/prop/PropellerDatasheet-v1.0.pdf

    I will change things to be similar to http://forums.parallax.com/forums/default.aspx?f=25&m=123910

    I am using a .1uF cap.

    Thank you for the assistance.
  • dgablerdgabler Posts: 7
    edited 2007-12-12 04:09
    Interesting when I tell it to identify hardware the prop chip reboots it would seem. So RES is getting through. What speed /stop/parity etc should the com port be set at? I have tried most settings including hardware flow control.....
  • Mike GreenMike Green Posts: 23,101
    edited 2007-12-12 04:30
    The Propeller is "commanded" to reboot whenever the DTR line is toggled. That's the way the boot loader gets control and it's the way the Propeller identifies itself. On any download sequence, the boot loader exchanges pseudo-random bit sequences, enough so the Propeller Tool "knows" that there really is a Propeller there. The end of the sequence sent by the Propeller is the chip version number. The Propeller Tool then tells the boot loader to stop (... Identify), download a program to RAM, download a program to RAM and copy to EEPROM, and an option to either run the downloaded program or stop after verifying the download.

    The Propeller Tool sets the speed to 115.2 Kbps with no flow control and the Propeller responds with the same as it receives. The data is encoded, one bit of data per byte (for control info) or 3 bits of data per byte (to download the program). The reason for this is that the Propeller's boot loader is running with the internal RCFAST clock which isn't accurate enough to do serial timing, so a ratiometric technique is used.
  • dgablerdgabler Posts: 7
    edited 2007-12-12 04:48
    wow Great info. So Data Parity and stop are not 8N1 but 4N1?
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