{"id":127,"date":"2013-10-31T02:09:14","date_gmt":"2013-10-31T02:09:14","guid":{"rendered":"http:\/\/voodoomanmiracle.com\/wp\/?p=127"},"modified":"2013-12-19T01:37:47","modified_gmt":"2013-12-19T01:37:47","slug":"fourthirty-mk-1","status":"publish","type":"post","link":"http:\/\/voodoomanmiracle.com\/wp\/?p=127","title":{"rendered":"FourThirty mk.1"},"content":{"rendered":"

\"91\"<\/a><\/p>\n

 <\/p>\n

I’ve been wearing my MSP430 watch<\/a> pretty regularly. It proved to be a practical timepiece, so I figured I’d have a go at a new version with some upgraded components.<\/p>\n

<\/p>\n

I will use the same OLED display from my previous watch design. While the power consumption of this display is rather high when active (up to 7ma @ 3v), the contrast and readability of the display is unmatched by any alternative. I will use the MSP430FR5738<\/a> in this design. This is a fairly new addition to the MSP430 series of 16-bit ultra low power microcontrollers from TI. The chip consumes as little as 1.5uA while maintaining a real-time clock and monitoring interrupts. The Ferroelectric RAM in this chip is also capable of zero-power data retention. \u00a0This allows for a neat trick that saves the clock variables across a reset or battery change; You don’t need to re-set the time. \u00a0The watch will also get an accelerometer. LIS3DH<\/a> seems like a good choice. I’m interested in it’s ability to autonomously detect ‘tap’ and ‘double tap’ events and fire an interrupt to wake the main processor. It even has an internal high-pass filter to reject gravitational acceleration. It should be able to share a SPI bus with the display. I’ll include a nice LDO and under-voltage protection for use with an unprotected li-po, but design primarily for a CR2016 or CR2025 coin cell. First step is to design symbols and footprints for EagleCAD and 3D models in Sketchup.
\n\"batthldtd300\"\"batthldsu300\"
\nNext, I put together the schematic and board layout. You may notice the huge ground plane. This was necessary to allow a CR2025 to fit in a holder designed for CR2016. By doing this, I will get a longer run time without compromising height. It also made routing rather difficult without resorting to a four layer board. You may notice some shortcuts I took to overcome the limitation.
\n\"sch300\"<\/a>\"brd300\"<\/a>
\nI could now import the board design into Sketchup and begin to design an enclosure.
\n\"3dboard300\"\"3dfull300\"
\nOrders were placed to Shapeways<\/a>, OSHPark<\/a>, and DigiKey<\/a>. Most of the components were soldered in my reflow (toaster) oven. \u00a0The display, battery holder, buttons, and programming header were hand soldered.
\n\"popd\"\"popd2\"
\n\"w22\"<\/p>\n

\"93\"<\/a>\"95\"<\/a><\/p>\n

Coding for most of the major functions is complete. I wear the thing most days. Some cool tricks with the accelerometer are possible, but coding is slow. I’m building from the ground up here, and I’m not a great coder. Future updates will be posted to this page.<\/p>\n

— Featured on hackaday.com —<\/a><\/p>\n","protected":false},"excerpt":{"rendered":"

  I’ve been wearing my MSP430 watch pretty regularly. It proved to be a practical timepiece, so I figured I’d have a go at a new version with some upgraded components.<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[1],"tags":[],"class_list":["post-127","post","type-post","status-publish","format-standard","hentry","category-uncategorized"],"_links":{"self":[{"href":"http:\/\/voodoomanmiracle.com\/wp\/index.php?rest_route=\/wp\/v2\/posts\/127","targetHints":{"allow":["GET"]}}],"collection":[{"href":"http:\/\/voodoomanmiracle.com\/wp\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"http:\/\/voodoomanmiracle.com\/wp\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"http:\/\/voodoomanmiracle.com\/wp\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"http:\/\/voodoomanmiracle.com\/wp\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=127"}],"version-history":[{"count":27,"href":"http:\/\/voodoomanmiracle.com\/wp\/index.php?rest_route=\/wp\/v2\/posts\/127\/revisions"}],"predecessor-version":[{"id":176,"href":"http:\/\/voodoomanmiracle.com\/wp\/index.php?rest_route=\/wp\/v2\/posts\/127\/revisions\/176"}],"wp:attachment":[{"href":"http:\/\/voodoomanmiracle.com\/wp\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=127"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/voodoomanmiracle.com\/wp\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=127"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/voodoomanmiracle.com\/wp\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=127"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}