!colspan="4" style="width:100%; text-align:left"; border-bottom:solid 2px #ededed"|History
|-
!style="border-left:solid 2px #73B2C7; border-right:solid 2px #73B2C7;border-top:solid 2px #73B2C7; border-bottom:solid 2px #73B2C7; background-color:#73B2C7; padding:5px; color:white"|ID#
!style="border-left:solid 2px #73B2C7; border-right:solid 2px #73B2C7;border-top:solid 2px #73B2C7; border-bottom:solid 2px #73B2C7; background-color:#73B2C7; padding:5px; color:white"|Issue Date
!style="border-left:solid 2px #73B2C7; border-right:solid 2px #73B2C7;border-top:solid 2px #73B2C7; border-bottom:solid 2px #73B2C7; background-color:#73B2C7; padding:5px; color:white"|Notes
|-
|style="border-left:solid 2px #73B2C7; border-right:solid 2px #73B2C7;border-top:solid 2px #73B2C7; border-bottom:solid 2px #73B2C7; background-color:#edf8fb; padding:5px; color:#000000"|X.Y.Z|style="border-left:solid 2px #73B2C7; border-right:solid 2px #73B2C7;border-top:solid 2px #73B2C7; border-bottom:solid 2px #73B2C7; background-color:#edf8fb; padding:5px; color:#000000"|012023/08/202302
|style="border-left:solid 2px #73B2C7; border-right:solid 2px #73B2C7;border-top:solid 2px #73B2C7; border-bottom:solid 2px #73B2C7; background-color:#edf8fb; padding:5px; color:#000000"|DESK-MP1-L-1.0.0 release
|-
<section begin=Body/>
== On-board Pheripheral RTC ==An on-board Maxim Integrated DS3232 device provides a very accurate, temperature-compensated real-time clock (RTC) resource with:
* Temperature-compensated crystal oscillator* Date, time On [[ETRA_SBC | SBC ETRA]] there are two rtc one on [[ETRA_SOM | ETRA SOM]] and calendar* Alarm capability* Backup power from external battery* ±3one on carrier board.5ppm accuracy from -40°C to +85°C * 236 Bytes of Battery-Backed SRAM * I²C Interface
Backup power is provided through the RTC_VBAT. If not used<pre class="workstation-terminal">root@desk-mp1:~# ls -la /dev/rtc*lrwxrwxrwx 1 root root 4 Aug 2 10:45 /dev/rtc -> rtc0crw------- 1 root root 253, RTC_VBAT must be externally connected to VCC.0 Aug 2 10:45 /dev/rtc0crw------- 1 root root 253, 1 Aug 2 10:45 /dev/rtc1</pre>
For a detailed description of RTC characteristics=== Device tree configuration === <pre>......&i2c4{ ... ... ds3232: rtc@68 { compatible = "dallas, please refer ds3232"; reg = <0x68>; interrupt-parent = <&gpiod>; interrupts = <6 IRQ_TYPE_EDGE_FALLING>; status = "okay"; }; ... ...};......&rtc{ status = "okay"; /* USER CODE BEGIN rtc */ /* USER CODE END rtc */};......</pre> === Linux messages at boot time === <pre class="workstation-terminal">...[ 2.006753] stm32_rtc 5c004000.rtc: registered as rtc0[ 2.010619] stm32_rtc 5c004000.rtc: setting system clock to 2023-08-02T10:45:30 UTC (1690973130)[ 2.019926] stm32_rtc 5c004000.rtc: registered rev:1.2...[ 2.177792] rtc-ds3232 1-0068: registered as rtc1...</pre> === Usage with ''hwclock'' === <pre class="workstation-terminal">root@desk-mp1:~# hwclock -f /dev/rtc1 -vhwclock from util-linux 2.37.4System Time: 1690975162.373458Using the rtc interface to the DS3232 datasheetclock.Assuming hardware clock is kept in UTC time.Waiting for clock tick......got clock tickTime read from Hardware Clock: 2023/08/02 11:19:24Hw clock time : 2023/08/02 11:19:24 = 1690975164 seconds since 1969Time since last adjustment is 1690975164 secondsCalculated Hardware Clock drift is 0.000000 seconds2023-08-02 11:19:23.549038+00:00</pre>
----
[[Category:ETRA]] [[Category:ETRA_SBC]]