I forgot to mention, that if somebody wants to play with freescale Kinetic cpu, there's an affordable development board (~10€): FRDM-KL25Z. You can source it form digikey, but you can also get it from ebay, shipping included, for ~20€[1].
[1]: http://www.ebay.com/sch/i.html?_sacat=0&_nkw=FRDM-KL25Z&_sop=15 On Mon, Sep 16, 2013 at 3:35 PM, Felix <[email protected]> wrote: > Yeaaah, schematics!! One silly question... do you plan to upload the kicad > library folders? or where can we get them? > > > On Mon, Sep 16, 2013 at 11:58 AM, Werner Almesberger < > [email protected]> wrote: > >> Felix wrote: >> > Should be possible something like following? >> >> I was thinking of having such a FET battery switch but since the MCU >> already seems to include a similar feature (*), I'd use that. >> >> The boost converter only gets enabled when using display or memory >> card. The transceiver must be powered whenever we need a precise >> clock, because it has the system's only crystal. >> >> Since the transceiver has an efficient built-in off switch and can >> run at voltages down to 1.8 V, I'll simply connect it to the same >> USB-or-battery supply as the MCU. >> >> I also placed a fat silo cap (220 uF) on that system voltage rail, to >> keep the RTC running when swapping batteries. Will have to see if the >> MCU can respond sufficiently quickly and whether "deep standby" current >> is low enough for this to work properly. >> >> The RTC's clock would come from an internal RC oscillator that can be >> trimmed by occasionally comparing with the 15 ppm crystal reference. >> >> I'm not entirely sure whether I interpreted the MCU's power routing >> correctly but a few experiments should clarify that :-) By the way, >> tentative schematics (still work in progress) and some rough component >> placement on the PCB are now in the repository: >> >> https://gitorious.org/pwsafe/pwsafe/source/hw >> >> (*) Figure 3-29 on page 93 of [1] and figure 36-2 on page 652. >> >> [1] >> http://cache.freescale.com/files/32bit/doc/ref_manual/KL25P80M48SF0RM.pdf >> >> - Werner >> >> _______________________________________________ >> Qi Hardware Discussion List >> Mail to list (members only): [email protected] >> Subscribe or Unsubscribe: >> http://lists.en.qi-hardware.com/mailman/listinfo/discussion >> > > > > -- > Felix > -- Felix
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