Measuring boot voltage on PandaBoard ES - part 1
What am I trying to do? Pandaboard ES OMAP4460 's main voltage rails are vdd_mpu, vdd_core, vdd_iva. MPU and IVA domains have dependency on Core (obvious since Core drives the common bus on OMAP called the L3 bus). Our intent here is to measure voltages of these rails and ensure they are the right voltage levels and in the right sequence as U-boot SPL comes up. Stage #1 - knowing what to measure This is pretty easy on most other boards, but on PandaBoard ES, things are a mite more interesting. Unlike most other OMAP3 and OMAP4430 boards, OMAP4460 on Pandaboard ES is powered by 2 PMICs!. A TPS62361 drives it's vdd_mpu rail while TWL6030 supplies the vdd_iva and vdd_core rails. lets look at each one in detail: (the following figures are excerpts from schematics of PandBoard ES) As seen in the schematics, TPS62361 is a slightly different beast to deal with. Three paramaters play an important role for the voltage to appear in the inductor at L23. is "EN...