BBAI SRM ------------ 6.1.1 TPS6590379 PMIC
One dedicated pin in each package can be configured as part of the power-up sequence to control external resources. General-purpose input-output (GPIO) functionality is available and two GPIOs can be configured as part of the power-up sequence to control external resources.
does anyone have more info on this?
also, what is a ‘package’ in this context?
This seems to be a direct quote from https://www.ti.com/lit/ds/symlink/tps659037.pdf, which is not the right way to write this section. I’ll revisit it.
Anyway, “package” in this context seems to be referring to different package options for the TPS659037 PMIC. TI only seems to document one package, so it appears this is a double-mistake as the Beagle documentation shouldn’t have copied this and the TI documentation is indeed confusing.
There is a specific sequence programmed into the PMIC and tied into the full orderable part number we use in the design, TPS6590379ZWSR. The “9” here following the “TPS659037” indicates the sequence programmed into the PMIC. TI will use the term OTP or one-time-programmable to talk about how they configure the devices in the factory.
What we really should document here is how we use the PMIC, which is most associated with the power-up and power-down sequences.
A quick check of e2e provides a reasonably researched question that describes much of what the differences are between the OTP settings, including the usage of the GPIO pins in the PMIC used to enable external power controls. TI’s answer simply confirms the researched question.
I’ll add that the “external” in this context is external to the PMIC, but still within the BeagleBone AI board. To determine when signals can be driven on the cape headers, you should use the VOUT_3V3 and RESET# signals to determine when it is safe to drive signals into the board.
Note: On BeagleBone Black, RESET# was a bi-directional signal, but it is only an output from BeagleBone AI to capes on BeagleBone AI.