Problem w serial comms ATmega128 <-> PC

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Problem with serial communications between ATmega128 and PC

I have used WinAVR and Peter Fleury's interrupt controlled uart library
successfully in the past with the STK500 board and the AT90S8515 and
ATmega16 devices. Moving on to a bigger project I purchased the STK501 board
with an ATmega128. Connecting it to the STK500 I can program the device with
the default xmas_tree_leds_flashing program so I assume it is working OK.
However, trying out a simple test_uart program I get nothing out of the
serial port. I have fiddled with fuses, clocks, pins etc. and still nothing.
There is probably something here that I have not understood, some setting or
connection that I should do and am not doing.

My setup:

- STK500+STK501 with the ATmega128 device
- default settings on all jumpers both boards
- RS232 spare pins to PD0 and PD1 on STK500
  (assume this still works with STK501/ATmega128 combo)
  - listen to PC com port with Bray's terminal application at 9600 baud
  - internal clock for device (no external osc) have tried all settings
    available on AVRStudio (latest version 4.12 - build 460) from 1 to 8 MHz.
    
My suspicion is that the 501 board uses another port for serial comms other
than portD or requires some other jumper? / connection? than the default
one.

Someone must have the same parts as I do and hopefully has this working.
Please give me some pointers on what I should look into.

Thank you

Re: Problem w serial comms ATmega128 <-> PC
On Sun, 4 Dec 2005 16:52:01 +0000 (UTC), snipped-for-privacy@otenet.gr (A. Drosos)

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The internal RC oscillator, especially if you don't apply the
calibration byte, isn't likely to be sufficiently close to the nominal
frequency to support reliable serial coms. Have you checked the TX pin?
Is there anything happening there at all?

--
Rich Webb   Norfolk, VA

Re: Problem w serial comms ATmega128 <-> PC
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Check the ATmega103 compatibility fuse. It is set by default.

Regards,
Alejandro.

Re: Problem w serial comms ATmega128 <-> PC
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I have used UART on internal oscillator for test purposes many times and I
never had troubles with internal oscillator frequency different from
nominal.

Best regards,
Jacek



Re: Problem w serial comms ATmega128 <-> PC
On Fri, 9 Dec 2005 00:37:23 +0100, "Jacek Meyerhold"

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Then you have never tested your devices over any sort of temperature
range. The inter oscillator changes quite a lot with temperature. For
any sort of device which should work years without problems you need
to test that it works over at least the temperature range -10 C to 70
C for reasonably hot regions. For desert countries, one probably need
to go to at least 85 C, and for cold countries probably down to -40 C.

Regards
  Anton Erasmus



Re: Problem w serial comms ATmega128 <-> PC

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The Mega128 requires a tristatebuffer at the normal serial 1 since the
  SPI programming pin is shared with the serial 1. There is also a
serial 2.

Rene
--
Ing.Buero R.Tschaggelar - http://www.ibrtses.com
& commercial newsgroups - http://www.talkto.net

Re: Problem w serial comms ATmega128 PC
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MHz.


Hi,

I think the problem is, that you use the wrong connection between the UAR
outputs and the STK500. Are you using the UART 0 ? If so you must connec
PE0 with SpareRx and PE1 with SpareTX - not PD0,1.

Good luck
   Michael





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