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<header class="entry-header"> <h2 class="entry-title"><a href="https://blogs.coreboot.org/blog/2015/07/13/gsoc-ech8s-firmware-week-6/" rel="bookmark">[GSoC] EC/H8S firmware week #6</a></h2> </header> <div class="entry-content"> <p>This week I looked at the communication between the EC H8S and the PMH4. The PMH4 (likely power management hub) is an ASIC which takes care of the power control. It controls who get’s power and who not. It聽doesn’t do any high level work, more like a big logic gatter. The PMH4 has inputs from several power good pins from different power rails and chips. On the output side it controls some power rails. It can also reset the H8S. The PMH4 also knows over some pins in which power聽state (ACPI S0,S4,S5) the board is.聽It doesn’t do any high level work. It’s more like a big logic gatter. There are no ADC on any power lines.</p> <p>The PMH4 is connected to the H8S via 4 Pins. ~OE LE DATA CLK.</p> <p><a href="https://blogs.coreboot.org/files/2015/07/pmh4_connector_t40.jpg"><img fetchpriority="high" decoding="async" class="alignnone size-medium wp-image-3858" src="https://blogs.coreboot.org/files/2015/07/pmh4_connector_t40-300x169.jpg" alt="gsoc 2015 pmh4 connector t40" width="300" height="169" srcset="https://blogs.coreboot.org/files/2015/07/pmh4_connector_t40-300x169.jpg 300w, https://blogs.coreboot.org/files/2015/07/pmh4_connector_t40-1024x577.jpg 1024w" sizes="(max-width: 300px) 100vw, 300px" /></a></p> <p>I connected a buspirate in SPI sniffer mode to debug the protocol. But the output looked a little bit strange. There was no data from the PMH4 to H8S (MISO) and the data comes in burst. To get more knowledge on the protocol I used a digital oscilloscope.</p> <p><a href="https://own.fe80.eu/index.php/s/w7uLLz7Qh1AvLHs" target="_blank">pmh4 oscilloscope</a></p> <p>The protocol doesn’t look like聽SPI. LE聽get’s low after every transmission, ~OE is just high, clock and data just transfer the data. Sometimes when the H8S gets an interupt the Clock pause for some time and continues with the data afterwards. The clock聽is around ~400kHz.</p> <p>I confirmed the protocol via the oscilloscope, but still I don’t get any sign from the board. No fan, nothing else. There must be more than this single transmisison. Maybe the board is to much damaged.聽My modified board was already broken when I got it. There is a聽loose connection related to the cardbus. Maybe this is my problem I don’t know.</p> <p>I’ve two board with two connectors for the PMH4 here. Why not using the OEM one as starter help for the other one?</p> <p><a href="https://own.fe80.eu/index.php/s/1WPi7P3AIKBS7b7" target="_blank">t42 gives some starting help</a></p> <p>I think the PMH4 does what it should do. The H8S has an digital-analog-converter pin connected to the video聽brightness. But I haven’t implemented it yet. But I don’t think the device booted, because neither the CPU nor the chipset produce any heat. Ok, maybe it does, I only used my finger as thermometer.聽A thermal camera would help here.聽I’ll borrow a thermal camera for that.</p> <p>There are lot of pins which I ignore atm. E.g.聽A20 pin. Is there聽something to do in a specific time serie?</p> <p><strong>What’s next?</strong></p> <ul> <li>build a small protocol sniffer for the PMH4 XP using a msp430 or stellaris arm</li> <li>make progress on the bootloader</li> <li>find a way to聽flash back the OEM H8S firmware</li> <li>find a way to flash my bootloader聽via OEM flash tools</li> </ul> <p>My requirements to the bootloader are</p> <ul> <li>UART flashing via XMODEM</li> <li>a simple UART shell</li> <li>I2C as recovery and shell as well</li> </ul> <p>I2C pins are a lot easier to find and modify than the H8S UART.聽I’m not yet聽sure if the H8S should be the master or the slave and on what address he should聽use? Multiple? UART tx is working. Rx聽is聽a task to do.</p> <p><strong>PMH4 / PMH7 / Thinker communication</strong></p> <p>On newer board the PMH interfaces changed (>= x60, t60, …). They merge the LPC interface and the聽XP interface into an protocol over聽SPI. And the聽new PMH is used as GPIO expander as well.</p> <p><a href="https://blogs.coreboot.org/files/2015/07/pmh4_pmh7_thinker_communication.png"><img decoding="async" class="alignnone size-medium wp-image-3859" src="https://blogs.coreboot.org/files/2015/07/pmh4_pmh7_thinker_communication-232x300.png" alt="pmh4 pmh7 thinker communication" width="232" height="300" srcset="https://blogs.coreboot.org/files/2015/07/pmh4_pmh7_thinker_communication-232x300.png 232w, https://blogs.coreboot.org/files/2015/07/pmh4_pmh7_thinker_communication-791x1024.png 791w, https://blogs.coreboot.org/files/2015/07/pmh4_pmh7_thinker_communication.png 850w" sizes="(max-width: 232px) 100vw, 232px" /></a></p> <p> </p> </div> <footer class="entry-footer"> <span class="posted-on"><span class="screen-reader-text">Posted on </span><a href="https://blogs.coreboot.org/blog/2015/07/13/gsoc-ech8s-firmware-week-6/" rel="bookmark"><time class="entry-date published updated" datetime="2015-07-13T20:32:02+00:00">July 13, 2015</time></a></span><span class="byline"><span class="author vcard"><span class="screen-reader-text">Author </span><a class="url fn n" href="https://blogs.coreboot.org/blog/author/lynxis/">Alex Couzens</a></span></span><span class="cat-links"><span class="screen-reader-text">Categories </span><a href="https://blogs.coreboot.org/blog/category/coreboot/" rel="category tag">coreboot</a>, <a href="https://blogs.coreboot.org/blog/category/gsoc/" rel="category tag">GSoC</a></span><span class="tags-links"><span class="screen-reader-text">Tags </span><a href="https://blogs.coreboot.org/blog/tag/ec/" rel="tag">ec</a>, <a href="https://blogs.coreboot.org/blog/tag/gsoc/" rel="tag">GSoC</a>, <a href="https://blogs.coreboot.org/blog/tag/gsoc2015/" rel="tag">GSoC2015</a>, <a href="https://blogs.coreboot.org/blog/tag/h8s/" rel="tag">h8s</a>, <a href="https://blogs.coreboot.org/blog/tag/pmh4/" rel="tag">pmh4</a>, <a href="https://blogs.coreboot.org/blog/tag/pmh7/" rel="tag">pmh7</a>, <a href="https://blogs.coreboot.org/blog/tag/thinker/" rel="tag">thinker</a></span> </footer> </article> </main> </section> </div> <footer id="colophon" class="site-footer" role="contentinfo"> <div class="site-info"> <a href="https://wordpress.org/">Proudly powered by WordPress</a> </div> </footer> </div> </body> </html>