Date: Thu, 22 May 2014 08:53:05 -0600 From: Ian Lepore <ian@FreeBSD.org> To: Luiz Otavio O Souza <lists.br@gmail.com> Cc: "freebsd-arm@freebsd.org" <freebsd-arm@FreeBSD.org> Subject: Re: BBB MMC / SD detection instability with U-Boot 2014.04 (CPU 1GHz) Message-ID: <1400770385.1152.233.camel@revolution.hippie.lan> In-Reply-To: <CAB=2f8xyzLQpTQgwc8EHh-_A-0HV_H3w_7uW_RAYXM8X_Q02MA@mail.gmail.com> References: <CADH-AwGb36EUknNofdch1Q4Pn8GAN%2BEp9SdiJ_f7Q2v9e4kW1g@mail.gmail.com> <20140522.204656.144162099.toshi@ruby.ocn.ne.jp> <1400765234.1152.224.camel@revolution.hippie.lan> <20140522.231553.186386229.toshi@ruby.ocn.ne.jp> <CAB=2f8xyzLQpTQgwc8EHh-_A-0HV_H3w_7uW_RAYXM8X_Q02MA@mail.gmail.com>
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On Thu, 2014-05-22 at 11:34 -0300, Luiz Otavio O Souza wrote: > Just picking one email to reply... > > This is probably unrelated, but i can consistently corrupt my SD Card > data if i connect (and use) a very small R/C servo (the 9g ones, used > on foam planes) to the 3.3v on the expansion headers. > > I'm not sure if it is because of noise or the power consumption, but > looks like the BBB is really picky about the power conditions here. > > Connecting the servo to the VDD_5V on the same header makes the problem go away. > > So be careful about what you connect on your boards :) > It looks like the 3v3b rail comes off a 500mA LDO and is already powering several of the onboard chips (including eMMC and at least part of the ethernet phy), so it may be power consumption. -- Ian
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