[OpenTRV-dev] Bootloader stuggles!

[Kevin Wood]

Ahh. Yes, that is a valid point. I think current draw does give you more
"mips per watt" at lower clock rates, but as long as it's only executing
instructions for a minute proportion of the battery life, it may not make
much difference.

Supply voltage is an issue, though.

I'll have a look at the bootloader code if I get a chance, and see if
there's anything obvious. If we can adopt a "non standard" BAUD rate it
ought to be possible.

Kevin

> I generally do "race to sleep", but you can't run above 4MHz at the bottom
> end of the voltage range...
>
> Rgds
>
> Damon
>
>
> On 16 Apr 2013, at 20:40, Stuart Poulton wrote:
>
>> Slower isn't always better. Sometimes better to run through the code
>> quicker.
>>
>> On 16 Apr 2013 20:30, "Damon Hart-Davis" <EMAIL ADDRESS HIDDEN> wrote:
>> Carry on, please!
>>
>> I'm very much still feeling my way here.
>>
>> Rgds
>>
>> Damon
>>
>> On 16 Apr 2013, at 20:28, Stuart Poulton wrote:
>>
>> > Just floating ideas.
>> >
>> > On 16 Apr 2013 20:27, "Damon Hart-Davis" <EMAIL ADDRESS HIDDEN> wrote:
>> > Hi
>> >
>> > Fewer parts, less space, and lower power potentially.
>> >
>> > 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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