Author Topic: Slower baudrates communication (autobaud)  (Read 396 times)

Rinin

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Slower baudrates communication (autobaud)
« on: August 03, 2017, 10:04:41 pm »
I'm trying to connect to Olimex LPC-H2294 (rev A) with 12MHz oscillator

With terminal programm I could see answer to "?" (Synchronized) only on 300baud.
It is strange, but I realy want to flash device even if it'll take an hour.
Is it any way to connect on lower speed than 2400?

And another question about "oscillator" value, what it is used for in my case (autobaud), is it used at all, or mostly for another CPUs?

Andy Ayre

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Re: Slower baudrates communication (autobaud)
« Reply #1 on: August 04, 2017, 12:29:46 am »
With a 12MHz crystal you should be able to connect at 38,400 if not 57,600. Something is wrong. If you are using a USB to RS232 cable then try swapping it for a different one. We recommend genuine FTDI cables. Also try a different PC - could be a Windows driver issue.

Some parts require the crystal frequency to know how long erase and programming will take internally. Some parts don't need this. For the LPC2000 you should enter an accurate value.
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Rinin

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Re: Slower baudrates communication (autobaud)
« Reply #2 on: August 04, 2017, 01:10:16 am »
It's FTDI based converter and it works fine with the same board and default firmware.
Even on 7812bps (9600*12/14.7456) because default 14.7456MHz oscillator was replaced with 12MHz

I understand that it's not flash magic issue, but default firmware works ok and 12MHz oscillator seems also starting.
Thats why I want to flash it with 12Mhz RedBoot and forget about onchip bootloader.

Andy Ayre

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Re: Slower baudrates communication (autobaud)
« Reply #3 on: August 04, 2017, 03:15:52 am »
I have no idea why it can't autobaud at higher speeds. Perhaps put a scope on the Tx and Rx pins, send the '?' and see if anything looks strange. Or you could try using the high speed comms mode in Flash Magic.
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Rinin

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Re: Slower baudrates communication (autobaud)
« Reply #4 on: August 04, 2017, 12:55:11 pm »
Thank you, Andy for fast and professional responces, it is pleasure to meet such high level of support.

Issue was in opto-isolator of my USB-UART, it worked almost fine, but slightly affected first byte only.