ESP8266 Community Forum

- Sat Jun 24, 2017 8:56 am #67533

Thanks a lot. Any help wil be great.
This is my code right know.

https://pastebin.com/Yi2UepfX

The original program is for arduino ... I just change it a bit

try to use OS_TIMER_US, i tested and works! find in google how to active OS_TIMER_US, because is default "disable".. if you can't do this, tell me. i help you![/quote][/quote]


you can use 25MHz crystal with special pin function! (if you need). see GPIO FUNCTIONS in google.. i see an tutorial in PORTUGUESE teaching use OS_TIMER_US, go to end of tutorial and see, i try and work.
http://portal.vidadesilicio.com.br/soft ... o-esp8266/

- Sat Jun 24, 2017 9:02 am #67534 no, crystal frequency IS NOT 80MHz.
take a look and see: 26MHz

so what is the 80MHz? --> the cpu clock

how do you get 80MHz from 26MHz ??? not really a multiple --> PLL (cheap) so you will have phase jitter

What quality does the crystal have ??? probably low +/- --> ???ppm --> so the 80MHz will be ???

Temperature stability will be ???

As I wrote, your generated frequency needs to be within a window of several 10Hz +/- around the 77500Hz
stable for at least 2 minutes for the clock to detect one correct packet (usually they take several for security).

Don't get me wrong: I am not saying it is impossible. But without taking into account the real conditions and without necessary measuring equipment I doubt you will make it by just blindly coding along ...

Have fun ....

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- Sat Jun 24, 2017 9:48 am #67535

no, crystal frequency IS NOT 80MHz.
take a look and see: 26MHz

so what is the 80MHz? --> the cpu clock

how do you get 80MHz from 26MHz ??? not really a multiple --> PLL (cheap) so you will have phase jitter

What quality does the crystal have ??? probably low +/- --> ???ppm --> so the 80MHz will be ???

Temperature stability will be ???

As I wrote, your generated frequency needs to be within a window of several 10Hz +/- around the 77500Hz
stable for at least 2 minutes for the clock to detect one correct packet (usually they take several for security).

Don't get me wrong: I am not saying it is impossible. But without taking into account the real conditions and without necessary measuring equipment I doubt you will make it by just blindly coding along ...

Have fun ....

i have one frequencymeter and show 26MHz from pin special function, and 77kHz too.. let's see how ESP work.. i will post images later

- Sat Jun 24, 2017 12:17 pm #67543 The crystal in my nodemcu says 12 Mhz
You are right, without measuring equipment I am lost but it is just for fun and learning.
I'm learning a lot abour timers and interruptions with this proyect.
Well it is easy with a Arduino Uno or Attiny85, it will be fun that ESP8266 won't make it.

Thanks again for your comments, all of them are apreciated.

Get fun.

no, crystal frequency IS NOT 80MHz.
take a look and see: 26MHz

so what is the 80MHz? --> the cpu clock

how do you get 80MHz from 26MHz ??? not really a multiple --> PLL (cheap) so you will have phase jitter

What quality does the crystal have ??? probably low +/- --> ???ppm --> so the 80MHz will be ???

Temperature stability will be ???

As I wrote, your generated frequency needs to be within a window of several 10Hz +/- around the 77500Hz
stable for at least 2 minutes for the clock to detect one correct packet (usually they take several for security).

Don't get me wrong: I am not saying it is impossible. But without taking into account the real conditions and without necessary measuring equipment I doubt you will make it by just blindly coding along ...

Have fun ....

i have one frequencymeter and show 26MHz from pin special function, and 77kHz too.. let's see how ESP work.. i will post images later