EEVblog Electronics Community Forum
Electronics => Projects, Designs, and Technical Stuff => Topic started by: NivagSwerdna on May 27, 2020, 08:56:22 am
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I'm using a FT231X for the first time and having a bit of trouble ;)
From the PC side connecting into the FT231X all is good and I can run FT-PROG etc. If I connect realterm I can send in characters and get one of the LEDs to flash (I think the labels are the wrong way around but that is not a big deal), however on the other side if I generate characters at the PIC side I do not get an LED flash and neither do characters appear at the terminal.
I did not need hardware handshake so I left pins 19, 6, 18, 4, 5 & 2 disconnected.
I'm starting to wonder if pin 19 or 6 should not have been left floating?
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The unused pins may be left floating.
But this reset connection with C20 in series looks a bit strange to me. How is it connected to the uC?
Are you sure the uC is working correctly, have you hooked up a scope or LA?
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I've dealt with this type of problem before.
Lesson learned: Read the errata (https://www.ftdichip.com/Support/Documents/TechnicalNotes/TN_140_FT231X%20Errata%20Technical%20Note.pdf). :palm:
Try configuring one CBUS pin as a #Keep_Awake through FT-PROG and short that pin to ground.
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The unused pins may be left floating.
Good news
But this reset connection with C20 in series looks a bit strange to me. How is it connected to the uC?
I think that is OK
Are you sure the uC is working correctly, have you hooked up a scope or LA?
I did yesterday. Looks OK.
There are things that I cannot see.. specifically under the QFN.... so I was doubting myself.
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I've dealt with this type of problem before.
Lesson learned: Read the errata (https://www.ftdichip.com/Support/Documents/TechnicalNotes/TN_140_FT231X%20Errata%20Technical%20Note.pdf). :palm:
Try configuring one CBUS pin as a #Keep_Awake through FT-PROG and short that pin to ground.
That's interesting. I will explore that.
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This is what is going into Pin 1 of the FT231XQ
It's a long time since I probed serial lines but... is HI the default state? Maybe the FT231XQ is pulling it up at idle?
My test program should just be sending '*' at 1Hz... now '*' is 2A i.e. 0010 1010
and I see...
0010100 with the last zero being a stop bit... as in 8-None-1
But I don't see a start bit from the dsPIC33EV256GM006.... weirdWas reading it the wrong way of course... lsb is transmitted first. :palm:
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Yes, the idle state on a UART line is logic high.
You're seeing the correct signal. Start bit is logic 0, then you have your character (least significant bit transmitted first) and the stop bit, which is logic 1.
See example:
(https://image.slidesharecdn.com/uart-140320144212-phpapp01/95/uart-16-638.jpg?cb=1395326545)
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Not sure if it was heat damage or just my inability to hand solder QFNs but I replaced the QFN and on the 4th attempt it worked. Weird!