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99 lines
2.4 KiB
Markdown
99 lines
2.4 KiB
Markdown
---
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title: "RTC"
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aliases:
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- firmwareapi/pycom/machine/rtc.html
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- firmwareapi/pycom/machine/rtc.md
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- chapter/firmwareapi/pycom/machine/rtc
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---
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The RTC is used to keep track of the date and time.
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## Quick Usage Example
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```python
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from machine import RTC
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rtc = RTC()
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rtc.init((2014, 5, 1, 4, 13, 0, 0, 0))
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print(rtc.now())
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```
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## Constructors
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### class machine.RTC([id=0, ...])
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Create an RTC object. See init for parameters of initialisation.
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```python
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# id of the RTC may be set if multiple are connected. Defaults to id = 0.
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rtc = RTC(id=0)
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```
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## Methods
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### rtc.init([datetime=None, source=RTC.INTERNAL_RC])
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Initialise the RTC. The arguments are:
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* `datetime` when passed it sets the current time. It is a tuple of the form: `(year, month, day[, hour[, minute[, second[, microsecond[, tzinfo]]]]])`. Without argument, it will not reset the previously set time.
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* `source` selects the oscillator that drives the RTC. The options are
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* `RTC.INTERNAL_RC`: Internal RC resonator
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* `RTC.XTAL_32KHZ`: External 32KHz crystal
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For example:
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```python
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# for 2nd of February 2017 at 10:30am (TZ 0)
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rtc.init((2017, 2, 28, 10, 30, 0, 0, 0))
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```
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> `tzinfo` is ignored by this method. Use `time.timezone` to achieve similar results.
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### rtc.ntp_sync(server, [update_period=3600, backup_server])
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Inits the RTC and sets up up automatic fetch and update the time using NTP (SNTP).
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* `server` is the URL of the NTP server. Can be set to `None` to disable the periodic updates.
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* `update_period` is the number of seconds between updates. Shortest period is 15 seconds.
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* `backup_server` is the URL of the backup NTP server. Can be set to `None` to disable the periodic updates.
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Can be used like:
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```python
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rtc.ntp_sync("pool.ntp.org") # this is an example. You can select a more specific server according to your geographical location
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```
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### rtc.now()
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Get get the current `datetime` tuple as `(year, month, day, hour, minute, second, usecond, None)`
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### rtc.synced()
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Returns `True` if the last `ntp_sync` has been completed, `False` otherwise.
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### rtc.memory([data])
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Reads RTC memory contents or write data in passed Buffer in to RTC memory. The buffer has space to store 2048 bytes.
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Example:
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```python
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rtc = RTC()
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rtc.memory(b'10101010') # writes data in RTC memory
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rtc.memory()
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```
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Output:
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```python
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b'10101010'
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```
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## Constants
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* Clock source: `RTC.INTERNAL_RC`, `RTC.XTAL_32KHZ`
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