ETRA SOM/ETRA Evaluation Kit/Interfaces and Connectors/RTC
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RTC device[edit | edit source]
Description[edit | edit source]
There are two RTC devices on the Evaluation Kit, one is provided by the STM32MP1 SoC, the other is a Maxim DS3232M I2C device.
Both RTC can retain time and custom data over blackouts using a backup power source as:
- the lithium rechargeable battery (BT1) optionally mounted on the carrier board
- an external battery connected to J3 (alternate mounting option to the battery)
Signals[edit | edit source]
The following table describes the interface signals for J3:
| Pin# | SOM Pin# | Pin name | Pin function | Pin Notes |
|---|---|---|---|---|
| 1 | J18.14 | VBAT | can be configured for battery connection | |
| 2 | - | DGND | Ground |
Device mapping[edit | edit source]
RTC is mapped to /dev/rtc0 device in Linux.
Device usage[edit | edit source]
The peripheral can be accessed through the date and hwclock linux commands.
