I’m using MilkV Duo in a battery powered project with LTE modem connected over USB. MilkV Duo is acting as USB Host.
I’m trying to figure out a way to turn off the LTE modem by disabling USB host together with VBus power output.
I can see MilkV has power management capability in datasheet, but I can’t figure out how does it translate into Linux kernel driver.
Any help and ideas would be greatly appreciated.
Cheers
Han
Hi, Han.
You can control the pin named VBUS_EN on schematic.
pic here:
It’s GPIOB5.
u can control it through sysfs or application.
Hey Troy,
Thanks for the response. Which device did you get this schematic from? I’m using MilkV Duo, and the schematic looks a bit different. The VBus pin seems to connect directly to the chip.
Sry, I missed ur device
this is from duo-s.
however, u still can control the usb role.
switching it from host to slave. but if you want to disable the power, it is not possible just on Duo.
you can design a base board yourself(I’m not sure if other baseboards can achieve this function. If possible, can you provide the schematic diagram of your baseboard? ).
Why do you think disable on the duo is not possible?
IMO, the device have PM functionality which can switch vbus between input and output modes, and some registers to control it. Would it be fair to say: with some tweak, the chip could power down the usb vbus via register when I unload the usb driver?
I would like to ask where your current USB power supply comes from?
I powered it through VSYS
