Difference between revisions of "ETRA SOM/ETRA Hardware/Peripherals/Real Time Clock"

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__FORCETOC__
 
__FORCETOC__
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<section begin="Body" />
  
 
== Real Time Clock ==
 
== Real Time Clock ==
 
''TBD: se è presente un RTC specifico nel prodotto, riportare le ceratteristiche''
 
 
''TBD: di seguito un esempio dell'RTC del modulo Bora''
 
  
 
This chapter describes the technical specifications and features for the RTC component on the ETRA module.
 
This chapter describes the technical specifications and features for the RTC component on the ETRA module.
  
 
=== Features ===
 
=== Features ===
 +
The Real Time Clock available on ETRA SoM is based on STM32MP1 SoC.
  
An on-board Maxim Integrated DS3232 device provides a very accurate, temperature-compensated real-time clock (RTC) resource with:
+
The RTC supports the following standards and features:
* Temperature-compensated crystal oscillator
+
* calendar with subsecond, seconds, minutes, hours (12 or 24 format), week day, date, month, year, in BCD (binary-coded decimal) format
* Date, time and calendar
+
* automatic correction for 28, 29 (leap year), 30, and 31 days of the month
* Alarm capability
+
* two programmable alarms
* Backup power from external battery
+
* digital calibration circuit with 0.95 ppm resolution, to compensate for quartz crystal inaccuracy
* ±3.5ppm accuracy from -40°C to +85°C
+
* timestamp feature which can be used to save the calendar content
* 236 Bytes of Battery-Backed SRAM
+
* 17-bit auto-reload wakeup timer (WUT) for periodic events with programmable resolution and period
* I²C Interface
+
* the RTC clock sources can be:
Backup power is provided through the RTC_VBAT signal:
+
** a 32.768 kHz external crystal
 
+
** an external resonator or oscillator
* on Bora it is connected to J2.113
+
** the internal low power RC oscillator
* on Bora Lite it is connected to J1.22
+
** the high-speed external clock (HSE), divided by a prescaler in the RCC
 
+
* the RTC is functional in VBAT mode and in all low-power modes when it is clocked by the external crystal or oscillator
If not used, RTC_VBAT must be externally connected to GND. For a detailed description of RTC characteristics, please refer to the DS3232 datasheet.
+
* the RTC is supplied through a switch that takes power either from the VDD supply when present or from the VBAT pin
 +
* all RTC events (Alarm, WakeUp Timer, Timestamp) can generate an interrupt and wakeup the device from the low-power modes
 +
Backup power is provided through the VBAT signal connected to J1.14, for more detail see the [[ETRA SOM/ETRA Hardware/Pinout Table|Pinout table section]].
  
 +
If not used, VBAT signal must be externally connected to the VDD rail.
 
----
 
----
  
 
[[Category:ETRA]]
 
[[Category:ETRA]]

Revision as of 15:43, 30 December 2020

History
Version Issue Date Notes
0.9.0 Dec 2020 First Draft
[TBD_link X.Y.Z] Month Year TBD
... ... ...



Real Time Clock[edit | edit source]

This chapter describes the technical specifications and features for the RTC component on the ETRA module.

Features[edit | edit source]

The Real Time Clock available on ETRA SoM is based on STM32MP1 SoC.

The RTC supports the following standards and features:

  • calendar with subsecond, seconds, minutes, hours (12 or 24 format), week day, date, month, year, in BCD (binary-coded decimal) format
  • automatic correction for 28, 29 (leap year), 30, and 31 days of the month
  • two programmable alarms
  • digital calibration circuit with 0.95 ppm resolution, to compensate for quartz crystal inaccuracy
  • timestamp feature which can be used to save the calendar content
  • 17-bit auto-reload wakeup timer (WUT) for periodic events with programmable resolution and period
  • the RTC clock sources can be:
    • a 32.768 kHz external crystal
    • an external resonator or oscillator
    • the internal low power RC oscillator
    • the high-speed external clock (HSE), divided by a prescaler in the RCC
  • the RTC is functional in VBAT mode and in all low-power modes when it is clocked by the external crystal or oscillator
  • the RTC is supplied through a switch that takes power either from the VDD supply when present or from the VBAT pin
  • all RTC events (Alarm, WakeUp Timer, Timestamp) can generate an interrupt and wakeup the device from the low-power modes

Backup power is provided through the VBAT signal connected to J1.14, for more detail see the Pinout table section.

If not used, VBAT signal must be externally connected to the VDD rail.