# HG changeset patch # User Mychaela Falconia # Date 1495317946 0 # Node ID ac49d8814893ce88b1b479297e8d0376228a407d # Parent 7168f63fc3b89706688e8baf405ce268a1c8bf84 doc/RVTMUX: keepalive mechanism documented diff -r 7168f63fc3b8 -r ac49d8814893 doc/RVTMUX --- a/doc/RVTMUX Sat May 20 21:00:15 2017 +0000 +++ b/doc/RVTMUX Sat May 20 22:05:46 2017 +0000 @@ -235,3 +235,28 @@ The host utility for talking AT commands to a FreeCalypso GSM device via RVTMUX is fc-shell; it works via rvinterf just like fc-fsio and fc-tmsh. + +Keepalive mechanism +=================== + +Another FreeCalypso addition to TI's RVTMUX interface is our optional keepalive +mechanism. The FreeCalypso family includes many subprojects, and one of these +subprojects involves running modem-like firmware (control via AT commands only, +no local UI) on Mot C1xx phones. Having a device that was originally made to +be a phone with LCD and buttons turn into a serially-controlled pseudo-modem +(LCD stays dark, buttons do nothing) feels quite weird, and this situation is +exacerbated on low-end Mot C1xx models that have small RAM and thus require our +pseudo-modem fw to be flashed. + +Our optional keepalive mechanism is intended for the latter scenario. There +will be an optional feature added to pseudo-modem fw builds for C1xx targets +(not yet implemented as of this writing) to have the firmware send periodic +keepalive queries out the serial port, to see if there is a running rvinterf +process on the other end of the wire, and automatically power off if there is +no keepalive response. + +Code has been added to rvinterf to respond with a keepalive answer packet when +a keepalive query packet is received; the feature has been implemented on the +rvinterf side ahead of the target fw so that when and if we do get around to +implementing the target side, the necessary rvinterf support will be there +waiting for us.