Greetings, I have been working on an extended battery solution and I’m at the point where I’m digging into the electrical specs of the fw16. Following the information available on github I’ve started to prototype a solution, getting into the electrical specifications now I’d like to know if anyone can clarify a few things. I’m not an EE but have built simple circuit boards in the past and of course worked with Pi’s/Arduinos and decided I want to start fiddling with my fw16.
While there is documentation and I appreciate that it exists, I immediately ran into some things I’m going to need more clarity on from the specs.
As per the information here : ExpansionBay/Electrical at main · FrameworkComputer/ExpansionBay · GitHub
VADP_GPU - appears to be available to both send or receive power, is this correct?
The pins have a current of 0.75A - is this managed per pin? What I’m getting at here is would I expect to get a maximum of 4.5A using all the pins, what if I used just two? Would current then be limited to 1.5A in either direction? Or is this merely a theoretical/safe maximum?
GPIO0_EC - This is labeled as “I/O pin for second battery” and has a type of CMOS, and OD as input/output. So first, clarification on that? This is under the power section still so I wouldn’t expect these to be a type of communication/I2C but this description makes it seem like its some sort of communication pin?
GPIO1_EC - Description of this pin is “Connect to EC GPIO on mainboard, control 2nd battery discharge and DP_HPD from dGPU PD controller.” And frankly, this means nothing to me, what is EC? What is DP_HPD? What is the dGPU PD controller? Seems like some sort of power management.
Finally what are the fan connectors, is there a part # or equivalent that I can use to order a matching set should I end up going through with making a DB? On that note - which pins are connected to each fan header, does it matter? One set goes to the left fan and one goes to the right fan I presume.
If I had to summarize my ask here for the electrical solution, its this : Is there an existing combination of pins that can be used to manage both the charging and discharging of an additional battery, and if so which ones to use? In addition to that are any of these setup to communicate back to the fw16 regarding battery status, and if so which ones? Does there need to be a handshake process to control the flow in/out of power or can it merely flow as voltage/electrical demand dictates?
The battery itself will have some safety circuits built into it but I’m trying to figure out how complex the transfer of power to/from the fw16 needs to be after that.