Tim = Timer(2, prescaler=83, period=4) ,source clock is 84Mhz,not 84Hz

OpenMV Boards
1 
# Timer Control Example
#
# This example shows how to use a timer for callbacks.

import time , micropython
from pyb import Pin, Timer, LED#'Timer' has no attribute 'PERIODIC'

blue_led  = LED(3)
def tick(timer):
    global Timeout_counter
    blue_led.toggle()
    print('-T2 out-')

tim = Timer(2, prescaler=83, period=4)#<----------------clock is 84Hz, right?
tim.callback(tick)
Timeout_counter=0
while (True):
    time.sleep_ms(1000)
    Timeout_counter+=1

now i find the docs in english,
https://docs.openmv.io/library/pyb.Timer.html#pyb-timer

**

Timers 2-7 and 12-14 have a clock source of 84 MHz.

image
image1437×817 120 KB

**
not 84Hz. :sweat:
https://docs.singtown.com/micropython/zh/latest/openmvcam/library/pyb.Timer.html

image
image1360×661 73.1 KB

i change my code to:

from pyb import Timer
from pyb import Pin, LED

tim = Timer(2, prescaler=84000000-1, period=2)
tim.counter() # get counter value
tim.callback(lambda t: LED(1).toggle())

timer clock =84MHz/(84000000)=1,so timer2 should be overlope 2seconds later since period=2.
but the led don’t blink. why?
now i know that the 84000000 is out of range 65535.

2

Hi, can you not use the PYB module: class Timer – control hardware timers — MicroPython 1.20 documentation

Use the machine module instead. It looks like the documentation for that is valid for the Cortex M4.

The pyb module will be phased out.

3

roger that .thank you.

tim = Timer(2, prescaler=(84000000-1), period=10)
tim.callback(lambda t: LED(1).toggle())
print(tim.freq())#450.938

if code change to tim = Timer(2, prescaler=(84000-1), period=1000), the out put is 12.9853
what is the formula for tim.freq？

4

Depends on the camera you have. If it’s the H7 then it should be 240 MHz.