Arduino library for millis64 micros64 millis32 micros32, time counters with optional offset.
Experimental
This library implements 64 bit time counters optional with offset.
It also provides 32 bit versions with optional offset.
These functions were inspired by code from docdoc to count millis() rollOvers.
When using an offset, one typically has to use the same offset throughout your whole program or only slightly adjust if needed, e.g. after an external reference pulse of an RTC or from data from an NTP packet.
The millis64() and micros64() are build upon the existing millis() and micros() functions and therefore slower of course.
As always, constructive feedback is welcome.
Some boards already implement millis64 and/or micros64. If so one could not use this library as is (but it is fairly easy to adapt)
| board | millis64 | micros64 |
|---|---|---|
| UNO R3 | N | N |
| ESP32 | N | N |
| ESP8266 | N | YYY |
| M4 | N | N |
| RPIpico | N | N |
To print the 64 bit timestamp one can use
- https://github.com/RobTillaart/printHelpers (includes HEX printing too)
The millis64() and micros64() functions are slower than micros() and millis() so not always optimal for all projects.
Run the millis64_performance.ino to get an indication of the performance on your platform of choice to see if it meets your needs.
Indicative times for 1000 calls in micros for Arduino UNO.
| function | UNO |
|---|---|
| millis() | 1452 |
| millis32() | 1444 |
| millis32(offset) | 1696 |
| millis64() | 3900 |
| millis64(offset) | 5096 |
| micros() | 3716 |
| micros32() | 3716 |
| micros32(offset) | 3964 |
| micros64() | 6288 |
| micros64(offset) | 7488 |
Be aware that the functions in this library will drift in time due to interrupts, deviations in frequency of crystals, resonators, and more. Also the values of the millis64 and micros64() is not persistent. So do not use them to replace a professional (atomic) clock.
#include "millis64.h"- millis64(uint32_t offset = 0) offset is optional.
Returns an unsigned 64 bit integer, milliseconds since start of sketch.
This function rolls over (offset === 0) after approx. 213 billion days > 500 million years.
- note: function must be called at least once every 24 days to not miss a rollover.
- micros64(uint32_t offset = 0) offset is optional.
Returns an unsigned 64 bit integer, microseconds since start of sketch.
This function rolls over (offset === 0) after approx. 213 million days > 500.000 years.
- note: function must be called at least once every 30 minutes to not miss a rollover.
The library has commented versions of the (offset) functions that only need to be called once in 49 days / 70 minutes. However these are slower so not preferred. And it should not be too much trouble to call them twice or?
These functions add an optional offset to the millis() and micros(). This allows e.g. to do roll over testing or align the millis32() with an external clock. The latter could be based upon an RTC or NTP.
- millis32(uint32_t offset = 0) idem.
- micros32(uint32_t offset = 0) idem.
- improve documentation
- uint32_t nano() would be great to have (some protocols might like them)
- void delayNano() would be great to have (some protocols might like them)
- investigate 64 bit offsets.
- investigate a millis64 class, esp. performance.
- example to sync offset with an NTP packet. (needs 64 bit offset?)
- delay64() no blocking for so long...
- delayMicros64() no blocking for so long...
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