R91 is NM, so the ID pin of the USB connector is not actually connected to the CPU. USB0ID_1 is not connected to anything useful. It is connected to TP22 though, so you can monitor it, however TP22 is in the middle of the back of the circuit board, which means you have to unsolder the battery leads to get to it. Maybe the pin definitions in arch/arm/mach-davinci/board-legoev3.h need to be patched.ĭRVVBUS is not connected to anything useful. Here is the circuit in question (from the link). Recompile linux 3.16.1-8-ev3dev-pre with: I don't think using a powered USB hub would suffice because (1) the AM1808 probably monitors VBUS to detect overcurrent, and (2) the hub probably needs to see +5V before it will enumerate.įrom what I read in TI forums it is important to switch the port to Host mode before driving VBUS, otherwise the MUSB logic may decide that it is already connected as a B-device from a previous session, and refuse to switch to host mode. As a workaround I intend to supply +5V externally (e.g. Hopefully the only thing that prevents the mini-B port from acting as a USB 2.0 Host is that the EV3 lacks circuitry to drive VBUS to +5V when the USB0_DRVVBUS pin toggles. In principle OTG requires a mini-AB receptacle, but there are OTG cables on the market with a Type-A receptacle at one end and a mini-B plug with grounded ID at the other end. Furthermore, it also displays the currently configured time zone of the system (which is UTC by default in our images).As mentioned in issue 43, the mini-USB port of the EV3 is OTG capable as far as the AM1808 is concerned. The timedatectl allows displaying the current time, both, the system clock and the hardware clock. Note: To let one of the RTCs retain the time even when no power is applied to the system, put a backup battery in the respective holder on the carrier board. Traditionally, on power off, the system clock will get stored into the hardware clock by a shutdown script. You can display the current time, set a hardware clock to a specified time, set a hardware clock to the system time, and set the system time from the hardware clock. The system clock will not get stored into the hardware clock on shutdown.Īlternatively, there is the tool hwclock for accessing one of the hardware clocks directly. When using the timedatectl utility, the time will get stored into the hardware clock immediately when setting a new date or time. Our images use systemd-timedated and the timedatectl command since V2.1 and sytemd-timesyncd since V2.4 to synchronize time with a remote Network Time Protocol (NTP) server.
From that point onward the system clock is used to track time. At boot time, the hardware clock is read and used to set the system clock. The second clock is called the ‘ system clock/tick’ or ' kernel clock' and is maintained by the operating system. This is the battery-backed clock that keeps time even when the system is shut down. Two clocks are important in Linux: a ‘ hardware clock’, also known as RTC, CMOS or BIOS clock.
#DCLOCK USB C TO CONSOLE HOW TO#
This article describes how to use a Real-Time Clock (RTC) on Embedded Linux. Is this page helpful? Real-Time Clock / RTC (Linux) Purpose
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