[OpenTRV-dev] Bootloader stuggles!

[Damon Hart-Davis]

And in any case, if I run the thing with a crystal slow enough to work at 1.8V I'm still going to get a strange baud for programming as things stand.

(I have reduced my simple 1Hz core loop from ~13mA to ~0.31mA, at 8MHz and 5V so far today, so I'm on a roll.)

Rgds

Damon


On 16 Apr 2013, at 20:22, Stuart Poulton wrote:

> Is there some merit in still using a xtal, rather than relying on the internal osc?
> 
> On 16 Apr 2013 16:25, "Damon Hart-Davis" <EMAIL ADDRESS HIDDEN> wrote:
> But I'm assuming that this bootloader I'm using will end up running at 7200 * clockMHz, eg 115200 baud at 16MHz, unless I somehow get it rebuilt.
> 
> Anyhow, I'm having fun with power management (at 8MHz) at the moment, so I can come back to this issue later.
> 
> Rgds
> 
> Damon
> 
> 
> On 16 Apr 2013, at 16:17, Mike Stirling wrote:
> 
> > The main issue I have found with serial and the internal RC is that, accuracy aside, it isn't an ideal frequency for generating standard baud rates. Those FTDI cables will work at obscure baud rates as well, and this may work better. For example, I have the serial port on my sensor boards working reliably at 500 kbps with the internal RC set to 4 MHz.
> >
> > Mike
> >
> > ----------------original message-----------------
> > From: "Kevin Wood" EMAIL ADDRESS HIDDEN
> > To: "Closed list for developer discussions" EMAIL ADDRESS HIDDEN
> > Date: Tue, 16 Apr 2013 11:36:36 +0100
> > -------------------------------------------------
> >
> >
> >> I've had fun and games with serial ports on the internal RC oscillators
> >> before on some AVRs due to the (in)accuracy of the clock. It's not too bad
> >> if there are spaces between bursts of characters so the UART can re-sync
> >> but, if you're blasting data at it continuously, bear in mind that it can
> >> go out of sync eventually. Maybe now the baud rate is lower that's what's
> >> happening?
> >>
> >> Might be better from a point of view of removing barriers to people
> >> playing with the code if they don't have to first mess about with a
> >> non-standard boot loader? Just depends what the cost is in power
> >> consumption.
> >>
> >> Certainly, it ought to be straightforward to make any OpenTRV source code
> >> agnostic to the clock speed to keep that option open.
> >>
> >> Kevin
> >>
> >>> For a laugh have a look at:
> >>>
> >>> http://arduino.cc/forum/index.php/topic,160647.0.html
> >>>
> >>> I suspect that I have to build a specific bootloader .hex file set for
> >>> 1MHz and 9600 (or 4800, just to be super PICAXE compatible!) baud serial.
> >>>
> >>> Not sure how to do that yet.
> >>>
> >>> May give up for the moment and do the 8MHz version (RC internal osc, but
> >>> no divider) to at least flex some other muscles!
> >>>
> >>> Rgds
> >>>
> >>> Damon
> >>>
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> >>
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> >
> > --
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> >
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