No response from LPC


Today when I started up my MNT Reform I got the message:

Waking up LPC… 120%


No response from LPC

The percentage varies, I’ve seen from 104-200% before it return No response from LPC. The machine boots fine, the only issue is that I cannot view battery usage.

The battery monitor has been a bit iffy ever since my batteries got completely drained. I recharged them fully outside the MNT Reform. Then when I put them back in, the battery percentage has always been ??? even when I let them charge inside the laptop. So I was waiting for all batteries to go under 3.2V, then try and recharge them again to see if the LPC would calibrate. I have used the laptop ~1h each weekend for about a month or so. I flashed the new firmware Sep 28.

But today I encountered this issue. The batteries wasn’t completely drained when it happened, I could use the laptop for more than an hour before it died.

Any ideas how to fix it? I tried disconnect the batteries but no change. Should I just reflash the LPC firmware?


Not certain on the exact cause but I would consider reflashing the LPC, could potentially be that you’ve flashed the keyboard but using the old firmware on the LPC that doesn’t need woken up? They’d be somewhat but not fully compatible to have them mixed and cause some oddities.

I flashed both the keyboard and lpc, so I’m pretty sure I didn’t use an old firmware for the LPC. I used the 6642b62 commit last time. For both keyboard and LPC. And it’s been working fine for a month. But who knows maybe I messed something up.

I did a reflashing using the latest (e00dc65) and LPC now wakes up! And my batteries are in a worse state than I thought, some are down to 1.1V maybe that had something to do with the LPC acting up.

Yep, that’s an undervoltage condition, so LPC would probably do an automatic safety shutdown.

I tried flashing the LPC firmware using this guide with commit hash #33bcef3. When attempting to do, well, much of anything, such as turn on the computer, check battery status, etc, I receive the following output:

Waking up LPC... 247%

…then the dreaded No response from LPC.

I generally tend to leave the laptop plugged in, even when it’s powered off. My results are the same whether or not the laptop is plugged in.

I also cannot reflash LPC anymore, currently just abandoned this idea.

I wrote a guide how I flashed both, found here. Might be of help.

*edit: typo

Interesting… I had walked through that guide before and it didn’t seem to work for me at the time, but I did it again and managed to successfully flash the image! Thanks for taking the time to write it up.

Edit: it’s probably worth mentioning that I run Debian 11 and the package dependencies have slightly different names:

sudo apt-get install \
                     gcc \
                     gcc-arm-none-eabi \

I’m reflashing lpc several times a day so can only confirm it works reliably. What i noticed though is that sometimes kbd just cannot pick up the line so resetting it (eg. by disconnecting and reconnecting sysctl cable, while system is off, or both sysctl and usb when it is on) sometimes (but very very rarely) helps.
In my case I came to this because sometimes I’m loading experimental build (so hangs expected) but sometimes stable, but rarely kbd cannot sync with stable lpc and in this case resetting kbd usually helps.

Finally it worked. Also applied @devkev keyboard patch, finally I can use it!

In my case I was getting No response from LPC because I build it without make lpcrc command.

It has happened to me yesterday, “waking up” until 97%, then “no response”, and then it started trying to wake up again, in cycles. I could apparently solve it by pressing the LPC reset button once again.

There are some new LPC and Keyboard FW versions in the Git repo with serial related fixes. Might help!