# HG changeset patch # User Mychaela Falconia # Date 1539236662 0 # Node ID 700d6cff63bbbf4804812b29939bf1fe95b15704 # Parent f920c9a68d456046b30f3d5e5c68ec9622137233 FCDEV3B-repackaging: new ideas regarding quadband RFFE TSPACT wiring diff -r f920c9a68d45 -r 700d6cff63bb FCDEV3B-repackaging --- a/FCDEV3B-repackaging Thu Oct 11 04:58:17 2018 +0000 +++ b/FCDEV3B-repackaging Thu Oct 11 05:44:22 2018 +0000 @@ -251,10 +251,41 @@ If anyone ever does pay for the creation of a quadband version of our FreeCalypso modem solution, be it in BenQ's physical form factor or some other, -this quadband modem will need a different firmware build configuration: there -is no way to have the same fw image work on both triband and quadband modems -given that the RFFE control signals are different, and there would be no way for -the fw to autodetect which hw it is running on. But all of the other design -guidelines listed above should still be followed, so we can have only two fw -build configurations (triband and quadband) without an explosion of further -build variants for different GPIO wiring and whatnot. +what about the firmware? For a long time I thought that a quadband modem would +need a different firmware build configuration because of incompatible TSPACT +signals. Our current triband modem (copied from Openmoko) has them wired like +this: + +TSPACT2 = Tx high bands +TSPACT1 = Rx PCS band +TSPACT4 = Tx low bands + +But TI's original TSPACT wiring for the quadband RFFE on their Leonardo and +E-Sample boards was different: + +TSPACT2 = Tx low bands +TSPACT1 = Tx high bands +TSPACT4 = Rx GSM850 band + +These two TSPACT signal assignments are mutually incompatible, hence if we make +a quadband modem following TI's original Leonardo/E-Sample TSPACT wiring, it +won't be able to share the same fw with our triband modems. But then I got an +idea: what if we wire them up in our own creative way as follows: + +TSPACT2 = Tx high bands +TSPACT4 = Tx low bands +TSPACT5 = Rx GSM850 band + +Then we can have the same fw build configuration support both triband and +quadband FreeCalypso modems by driving the signals as follows: + +TSPACT1 = Rx PCS band +TSPACT2 = Tx high bands +TSPACT4 = Tx low bands +TSPACT5 = Rx GSM850 band + +TSPACT1 will be driven but unused on quadband modems, whereas TSPACT5 will be +driven but unused on triband ones like our current FCDEV3B. To me (Mother +Mychaela) being able to have the same fw among *all* FreeCalypso modem variants, +both triband and quadband, is more valuable than the symbolic act of recreating +TI's original RFFE wiring, hence I am now leaning toward this new approach.