[OpenTRV-dev] Bootloader stuggles!

Wed Apr 17 13:19:53 BST 2013

As it happens I now have a working bootloader for 1MHz (upload 4800bps) c/o tim7 at the Arduino forum!

http://arduino.cc/forum/index.php/topic,160647.msg1204176.html

And I'm down to ~20uA or less with my tinkering so far with a wave to the core 1Hz control loop from the PICAXE stuff.

http://www.earth.org.uk/OpenTRV/Arduino/bootloader/ATmega328P-1MHz/BlinkPower.ino

Rgds

Damon

On 16 Apr 2013, at 22:15, Kevin Wood wrote:

> 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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