Open Source Thinkpad T420 Battery Design

Re:Open Source Thinkpad T420 Battery Design by iam4722202468 on Saturday August 29, 2020 @10:58PM (#24321011)

Yeah, this is still needed even with coreboot. The attiny isn't doing anything too complicated, it's just there to tell the laptop the status of the battery. In the testing I did, if you supply 12v without any of the SMBus stuff the laptop will shut off after a few minutes of use.

I'm actually looking in to making a slice battery, it should be possible but sourcing the docking connector seems to be much harder than getting the battery connector.

[ Parent | on HN ]

Re:Open Source Thinkpad T420 Battery Design by castratikron on Saturday August 29, 2020 @11:15PM (#24321084)

Would it be possible to write directly to /dev/i2c in Linux and spoof the messages? Not sure what the use case of this would be, but might be useful for something.

[ Parent | on HN ]

Re:Open Source Thinkpad T420 Battery Design by iam4722202468 on Saturday August 29, 2020 @11:19PM (#24321109)

Yep definitely, I had this exact thought last night and found an example kernel module to spoof a battery, and one to read i2c messages. There's probably all kinds of cool things you can do with a kernel module to communicate between the laptop's i2c port and a microcontroller. The docking connector conveniently has an i2c port on it, maybe I'll look in to this in the future

[ Parent | on HN ]