Just a simple question: How long does it take a "picaxe" flavor of pic chip to start running basic programs from power on? Thinking about a little circuit that steals it's operating power from the load it is driving, which is switched on/off at low rates.
thanks, bill
I couldn't say -- but it'll be more (perhaps a lot more) time than a purpose-built system that's coded in assembly.
Is there enough power available to put the chip into some sort of low- power mode except when you need it? That would make it come up and spin a lot quicker.
-- Tim Wescott Control system and signal processing consulting www.wescottdesign.com
give me a few days and I will find your answer. I suspect it is in the order of 2 milliseconds.
-- We have failed to address the fundamental truth that endless growth is impossible in a finite world.
Plan 'B' is to run the pic from a coin cell battery & sense when the main power is available before doing any output port activity.
low number of milliseconds would be no problem at all for this 'toy' circuit. It just has to be fast compared to a human response time. Thanks for your kind offer!
-0800, Bill Mart>
pin
Brownout detector (low power level) only detect and suspend operations. It does not put the chip into low power mode. If power is off for long enough, you will lose all data rams and register contents. Unless your application is completely stateless, this is not easy to do.
PIC running at 32KHz should last months on a coin cell or years on AAs, if you can afford the space. However, you must have complete control of the micro and disable all unnecessary functions. Namely, difficult to do with picaxe.
Taking a bit longer to get to than I expected.
-- We have failed to address the fundamental truth that endless growth is impossible in a finite world.
No problem, it turns out I may not need the PIC for version 0 of this circuit. Found a near-perfect part from Supertex, HV7100, for speed control of dc brush type motors. It drives a high side P channel mosfet, which is just right for my purposes. still curious how long a picaxe part needs to get going, but no urgent need to know. Still interested for a possible more advanced control version of my circuit, but that's only if there is actual interest in the simple version.
Thanks again for offering to help out a bit! Bill
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