<html><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;"><head><meta http-equiv="Content-Type" content="text/html charset=utf-8"></head><div class=""><br class=""><div><br class=""><blockquote type="cite" class=""><div class="">Begin forwarded message:</div><br class="Apple-interchange-newline"><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px;" class=""><span style="font-family: -webkit-system-font, Helvetica Neue, Helvetica, sans-serif; color:rgba(0, 0, 0, 1.0);" class=""><b class="">From: </b></span><span style="font-family: -webkit-system-font, Helvetica Neue, Helvetica, sans-serif;" class="">Mark Webb-Johnson <<a href="mailto:mark@webb-johnson.net" class="">mark@webb-johnson.net</a>><br class=""></span></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px;" class=""><span style="font-family: -webkit-system-font, Helvetica Neue, Helvetica, sans-serif; color:rgba(0, 0, 0, 1.0);" class=""><b class="">Subject: </b></span><span style="font-family: -webkit-system-font, Helvetica Neue, Helvetica, sans-serif;" class=""><b class="">[Ovmsdev] OVMS Hardware v3.1</b><br class=""></span></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px;" class=""><span style="font-family: -webkit-system-font, Helvetica Neue, Helvetica, sans-serif; color:rgba(0, 0, 0, 1.0);" class=""><b class="">Date: </b></span><span style="font-family: -webkit-system-font, Helvetica Neue, Helvetica, sans-serif;" class="">10 January 2018 at 2:41:58 PM HKT<br class=""></span></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px;" class=""><span style="font-family: -webkit-system-font, Helvetica Neue, Helvetica, sans-serif; color:rgba(0, 0, 0, 1.0);" class=""><b class="">To: </b></span><span style="font-family: -webkit-system-font, Helvetica Neue, Helvetica, sans-serif;" class="">OVMS Developers <<a href="mailto:OvmsDev@lists.teslaclub.hk" class="">OvmsDev@lists.teslaclub.hk</a>><br class=""></span></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px;" class=""><span style="font-family: -webkit-system-font, Helvetica Neue, Helvetica, sans-serif; color:rgba(0, 0, 0, 1.0);" class=""><b class="">Reply-To: </b></span><span style="font-family: -webkit-system-font, Helvetica Neue, Helvetica, sans-serif;" class="">OVMS Developers <<a href="mailto:ovmsdev@lists.teslaclub.hk" class="">ovmsdev@lists.teslaclub.hk</a>><br class=""></span></div><br class=""><div class=""><meta http-equiv="Content-Type" content="text/html; charset=utf-8" class=""><div style="word-wrap: break-word; -webkit-nbsp-mode: space; line-break: after-white-space;" class=""><div class=""><br class=""></div><div class="">Production…</div><div class=""><br class=""></div><div class="">Analog Lamb, while interesting, is just (a) too expensive (double the price), (b) unproven, (c) uncertified, and (d) has long lead times. Using proven Espressif certified modules seems the safer way to go.</div><div class=""><br class=""></div><div class="">So, we’ve decided to go with a switch to a standard certified ESP WROVER module, and external 16MB flash memory. The circuit board footprint for this is a little larger than the WROOM-32 module we’ve been using, and requires one more 3.3V->1.8V power conversion, but seems the safest way to go.</div><div class=""><br class=""></div><div class="">Accordingly, I’ve agreed with the China guys to proceed along these lines for the main board:</div><div class=""><br class=""></div><div class=""><div class="" style="margin: 0px; padding: 0px;"><ol class="MailOutline" style="margin-right: 0px; margin-left: 0px; padding: 0px 0px 0px 20px; list-style-position: inside;"><li class="" style="font-family: 微软雅黑; font-size: 14px; margin: 0px; padding: 0px;">Change WROOM-32 to WROVER (on circuit antenna version, similar to WROOM-32).<br class="" style="margin: 0px; padding: 0px;"><br class="" style="margin: 0px; padding: 0px;"></li><li class="" style="font-family: 微软雅黑; font-size: 14px; margin: 0px; padding: 0px;">We can free IO12 (SD_D2), IO13 (SD_D3), and IO4 (SD_D1), by using just 1-line SDCARD. I don’t really want to use IO12 as that is a bootstrapping pin.<br class="" style="margin: 0px; padding: 0px;"><br class="" style="margin: 0px; padding: 0px;"></li><li class="" style="font-family: 微软雅黑; font-size: 14px; margin: 0px; padding: 0px;">WROVER PSRAM uses IO16 and IO17, so we can’t use that for modem.</li><ul class="" style="font-family: 微软雅黑; font-size: 14px; margin: 0px; padding: 0px 0px 0px 20px; list-style-position: inside;"><li class="" style="margin: 0px; padding: 0px;">Move modem to IO4 and IO13.<br class="" style="margin: 0px; padding: 0px;"><br class="" style="margin: 0px; padding: 0px;"></li></ul><li class="" style="font-family: 微软雅黑; font-size: 14px; margin: 0px; padding: 0px;">Change to 1.8V 16MB flash chip (W25Q128FW?). As SDD_VDIO is not exposed, add a simple regulator 3.3V->1.8V for external flash?<br class="" style="margin: 0px; padding: 0px;"><br class="" style="margin: 0px; padding: 0px;"></li><li class="" style="font-family: 微软雅黑; font-size: 14px; margin: 0px; padding: 0px;">When burning e-fuses, need to take care with 1.8V/3.3V SDD_SDIO fuse - leave at 1.8V.<br class="" style="margin: 0px; padding: 0px;"><br class="" style="margin: 0px; padding: 0px;"></li><li class="" style="font-family: 微软雅黑; font-size: 14px; margin: 0px; padding: 0px;">Add capacitors for SD CARD and external Flash, as per Espressif example.<br class="" style="margin: 0px; padding: 0px;"><br class="" style="margin: 0px; padding: 0px;"></li><li class="" style="font-family: 微软雅黑; font-size: 14px; margin: 0px; padding: 0px;">Increase size of solder pad for big capacitors, and USB connector, to make it stronger.<br class=""><br class=""></li><li class="" style="font-family: 微软雅黑; font-size: 14px; margin: 0px; padding: 0px;">For the data lines of circuit traces SDCARD, SPI bus, external flash, take care to keep away from power traces or other sources of interference and keep the traces as short as possible.</li></ol></div></div><div class=""><br class=""></div><div class="">The change to WROVER is a PITA at this stage, but that 4MB PSRAM should give us more headroom and the extra bill-of-materials costs is just a couple of US$.</div><div class=""><br class=""></div><div class="">For the modem, we’re double-checking the power (which seems ok, but check to be sure), and changing passive -> active antenna. At the moment, it seems to be just a couple of passive components soldered inline between two easily accessible points. For existing developer modems in the field, we’ll try to make a simple upgrade kit (passive->active) for GPS, and post them out. If you don’t need GPS (such as Roadster users), the modem boards are functionally the same as the production ones.</div><div class=""><br class=""></div><blockquote style="margin: 0 0 0 40px; border: none; padding: 0px;" class=""><div class=""></div></blockquote></div></div></blockquote></div></div></body></html>