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On Mon, Feb 20, 2017 at 5:39 AM, Internet <[email protected]> wrote: > For all following suggestions you need a 1.8v power supply (buck > converter). First, you could disable internal pullups on the stm and remove > all pullups on PCB2 for the signals from the battery ic. Because the > signals are probably all opendrain you just need to pullup the signals on > pcb3 to 1.8v; either the stm or the battery ic can pull the lines low to > "activate" them. The stm should recognize 1.8v as high ... > > Second, you could add a txs0104 or two txs0102 (probably cheaper, you can > get those from aliexpress) for level shifting. They have internal pullups, > so you can remove the other pullup resistors as well. > yeahhh i was going to use a txs0104, but then decided to remove it from the board... i'll put it back. there are a couple of other signals (the IRQs) that need to be level-shifted up as well *sigh* a 1.8v voltage regulator just for a few micro-amps... :) > > Julius Lehmann > On Feb 19, 2017, at 22:56, Luke Kenneth Casson Leighton <[email protected]> > wrote: >> >> btw annoyinly the BQ27542 is designed for 1.8v operation, and the >> STM32F072 it's connected to operates its GPIO at 3.3v. suggestions on how >> to deal with this appreciated. >> >> l. >> >> ------------------------------ >> >> arm-netbook mailing list [email protected] >> http://lists.phcomp.co.uk/mailman/listinfo/arm-netbook >> <http://t224.mjt.lu/lnk/AEAAHqmkTZUAAAAAAAAAAGbE2wkAASHlFNUAAAAAAAZHgABYqoFBSB8SASpWSvugQRJH0axlFAAGAjk/1/CyGju87Q28FjUXb8DSKQqQ/aHR0cDovL2xpc3RzLnBoY29tcC5jby51ay9tYWlsbWFuL2xpc3RpbmZvL2FybS1uZXRib29r> >> Send large attachments to [email protected] >> >> > > _______________________________________________ > arm-netbook mailing list [email protected] > http://lists.phcomp.co.uk/mailman/listinfo/arm-netbook > Send large attachments to [email protected] >
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