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serial communication with chumby hacker board
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serial communication with chumby hacker board

by looksurly on Fri Sep 17, 2010 7:28 pm

I'm a bit stuck since I can't get any serial communication going with the board. I followed the serial port tutorial closely and modified the FTDI cable. Drivers are fine, I've used FTDI many times before. Voltages on cable are fine. I opened a serial terminal with exactly the properties as described in the tutorial. At this point I have yet to see any output from the board. I've triple checked the ground/tx/rx connections to make sure the right pins are there.

Is there a power reset? I have just been unplugging and plugging in the 5V dc power connector.

Any ideas?

thanks.
John
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Re: serial communication with chumby hacker board

by adafruit on Fri Sep 17, 2010 7:51 pm

press the little side button. can you also take a photo of your setup? just to make sure :)

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Re: serial communication with chumby hacker board

by looksurly on Fri Sep 17, 2010 8:33 pm

OK, I've tried that button many times. I can send you a pic tomorrow but my phone is at the office.

Notice that ground and tx (on the board) are on the outside pins (1 and 4, cf chumbyhackerboardbackbig.jpg) But in the picture chumbyftdi.jpg in the tutorial it shows yellow on pin 4 but says yellow should be rx. I must be color blind.
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Re: serial communication with chumby hacker board

by adafruit on Fri Sep 17, 2010 8:46 pm

TX connects to RX thats how data gets transmitted - transmit connects to receive on the other side and vice versa

follow the photos in the tutorial, they are correct

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Re: serial communication with chumby hacker board

by looksurly on Fri Sep 17, 2010 8:57 pm

OK, that's what I did first. nothing.
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Re: serial communication with chumby hacker board

by adafruit on Fri Sep 17, 2010 9:45 pm

gotta scope? :)

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Re: serial communication with chumby hacker board

by looksurly on Sat Sep 18, 2010 9:43 am

I can take it into the lab. tell me what you're looking for? testing the cable? well maybe I have a spare cable. send me your phone number via PM. otherwise this will take forever. or skype or chat or whatever. the forum is very low baud.
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Re: serial communication with chumby hacker board

by looksurly on Sat Sep 18, 2010 2:13 pm

gotta scope. now what?
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Re: serial communication with chumby hacker board

by looksurly on Sat Sep 18, 2010 2:49 pm

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Re: serial communication with chumby hacker board

by adafruit on Sat Sep 18, 2010 3:23 pm

unplug the FTDI
plug in power - 5V regulated!
do you see any LEDs light up?
now stick the scope on each of the four pins. one pin should be 3.3V, one should be ground, and then one should have pulses of data
clip the ground chip to one of the exposed holes, where its gold, thats ground

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Re: serial communication with chumby hacker board

by looksurly on Sat Sep 18, 2010 4:02 pm

5 V ps from Adafruit recommended for this board. unplug ftdi cable. plug in 5 v. first one then two leds come on.

with the ftdi now removed I connect the ground to the gold edge near the 4 pins and probe from ground to tx.

On the scope I see all dc signals. pin 1 0V. pin 2 3.3 V, pin 3 (rx on the board) 3.3 V, and pin 4 (tx on the board) .7 V. Pin 4 is a DC signal. No pulses. I'm using DC coupling but I should still see pulses.

Is that what you wanted to know?
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Re: serial communication with chumby hacker board

by adafruit on Sat Sep 18, 2010 6:45 pm

suspicious! :) lets do a return! please email support@adafruit and request a return label with a new chumby board. we'll investigate it further, beta hardware is like this sometimes

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Re: serial communication with chumby hacker board

by looksurly on Fri Sep 24, 2010 7:52 pm

the replacement board arrived and it works perfectly. I'll return the defective board asap.
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Please be positive and constructive with your questions and comments.