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stevech
Joined: 23 Feb 2006
Posts: 657
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Posted: 27 February 2006, 5:28 AM Post subject: ZX24 DTR vs laptop |
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My new Dell D810 laptop's serial port doesn't drive DTR in such a manner that the ZBasic compiler is able to download. <sigh>. The IDE does correctly display serial data coming from the module.
I suppose the one cable I have with me (at a customer's site) could be bad.
I doubt there's anything I can do about this. Maybe a USB to serial adapter? Is the timing with these OK? |
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mikep
Joined: 24 Sep 2005
Posts: 765
Location: Austin, TX
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Posted: 27 February 2006, 6:47 AM Post subject: |
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| Are you sure it is the laptop and not something else? Did you try a different scenario that works such as a second machine? In my experience it has always been my fault if I get a download error caused by the DTR line. |
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stevech
Joined: 23 Feb 2006
Posts: 657
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Posted: 27 February 2006, 16:27 PM Post subject: |
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| Yes, that board works OK connected to my desktop PC. The only things different are the cable and the laptop's serial port. laptops are notorious for having serial ports that are finnicky and have low RS232 voltages. |
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mikep
Joined: 24 Sep 2005
Posts: 765
Location: Austin, TX
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Posted: 27 February 2006, 16:43 PM Post subject: |
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That is a real problem. I have to use my laptop mini-docking station as it doesn't even have a serial port on the back. If you have a Dell docking station that would probably work.
Many people have had success with various USB to RS232 cables. I don't use one so I don't have any concrete suggestions. |
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dkinzer
Site Admin
Joined: 03 Sep 2005
Posts: 2499
Location: Portland, OR
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Posted: 27 February 2006, 17:10 PM Post subject: |
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| Quote: | | Maybe a USB to serial adapter? Is the timing with these OK? |
I have tried a few and some work while others don't. I have had consistently good results with adapters based on the FTDI FT232 chip. These are generally more expensive - typically $20 to $30. The cheap ones that I've tried cannot toggle the DTR line fast enough to get the ZX into download mode.
One source for an FTDI adapter is Parallax. Their price is $34. |
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dkinzer
Site Admin
Joined: 03 Sep 2005
Posts: 2499
Location: Portland, OR
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Posted: 27 February 2006, 18:34 PM Post subject: |
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| Quote: | | I suppose the one cable I have with me (at a customer's site) could be bad. |
The zload program has a test mode (the -a option) that can help diagnose the DTR connection. If you invoke zload thusly:
It will go into test mode and tell you what to look for. You'll need a voltmeter or other device capable of indicating a voltage level. |
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DH*
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stevech
Joined: 23 Feb 2006
Posts: 657
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Posted: 11 March 2006, 23:47 PM Post subject: |
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I found out why this laptop would not do a ZBasic download...
The RS232 cable (store-bought) that I had was not connecting pin 4 DTR. I measured 0 volts at the ZX24 end of the cable. I suspect that it was another of China's best - as it was "skinnier" than most cables. Don't know if they cheaped-out and didn't wire pin 4 or if it was merely defective.
I grabbed a different cable (fatter) and it worked fine.
Beware skinny RS232 cables. |
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