Set the time of Raspberry Pi Pico W using NTP

-

 While the new RPi Pico W does not have a battery to keep the RTC, it does have something the previous model was lacking, network connectivity. So using the built-in Wifi module it can figure out the time and date from a network server using the Network Time Protocol (NTP). 


It can work with it but the MicroPython binary I am using does not include a module for that at the moment (as the binary for ESP32 does) but it should not be a big deal to use that.

As usual, it was easier to say than to do, but now I have it working. Please note that if you use the Thonny program, it will adjust the Pico real-time clock without warning you. So for a while, you may think it was your code that did it when it may well it is not the case.

I just recycled some code I found but I was getting errors till I figured out the right offset for my board and timezone. You may need to tweak that to adjust it to yours.

try:
    import usocket as socket
except:
    import socket
try:
    import ustruct as struct
except:
    import struct

# (date(2000, 1, 1) - date(1900, 1, 1)).days * 24*60*60 = 3155673600
NTP_DELTA = 2208981600 #=1609459200+599522400   


# The NTP host can be configured at runtime by doing: ntptime.host = 'myhost.org'
host = "pool.ntp.org"


def time():
    NTP_QUERY = bytearray(48)
    NTP_QUERY[0] = 0x1B
    addr = socket.getaddrinfo(host, 123)[0][-1]
    s = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
    try:
        s.settimeout(1)
        res = s.sendto(NTP_QUERY, addr)
        msg = s.recv(48)
    finally:
        s.close()
    val = struct.unpack("!I", msg[40:44])[0]
    return val - NTP_DELTA


# There's currently no timezone support in MicroPython, and the RTC is set in UTC time.
def settime():
    t = time()
    import machine
    import utime

    tm = utime.gmtime(t)
    machine.RTC().datetime((tm[0], tm[1], tm[2], tm[6] + 1, tm[3], tm[4], tm[5], 0))

This is only useful once you have connected your board to the Internet, of course. In my case, I just do:

import ntptime
ntptime.settime()

and this sets the time on the Pico's RTC properly. 

Comments

Post a Comment

Popular posts from this blog

VFD control with Arduino using RS485 link

-
Image
Variable Frequency Drives ( VFD ) allow the control of spindles so speed can accurately be controlled and a detailed acceleration profile for the spindle and reverse rotation can all be handled. In essence a VFD is an three phase inverter for three-phase AC motor. I am using a popular (I mean cheap) Chinese VFD and though the reference manual is not great, I could see there is a built-in RS-485 port. I usually control the start, stop and speed selection using the keyboard on the unit but I thought it will be more useful if I could control everything from the same Arduino is doing our CNC table control. Some cheap RS-485 off eBay and some lines of code later, I can start, stop and change the speed from an Arduino. What a cool thing to have! Some configuration of your VFD are needed before you can use it like that.  You need to set PD163=1 (I am using address 1 in the code). PD=164=1 (for setting serial to 9600bps) and PD165=0 (for using ASCII and 8N1 character format)
Read more

How to get sinusoidal s-curve for a stepper motor

-
Image
After some experimentation, and delving a bit into the math of motion, I realized there can be a significant difference on the motion of a machine by just making small changes. A common and popular approach to smooth one axis of motion is to use a trapezoidal speed pattern, where acceleration and deceleration are uniformly accelerated movements (aka constant acceleration motion) separated by a portion happening at cruising speed. The problem comes with the fact that, while that approach is simple to understand and to code, it does contain sudden changes in the acceleration, that show as spikes on the acceleration derivative, called jerk. These sudden changes in the acceleration translate into undesired vibration in our machines. Most of that can be eliminated by selecting a motion pattern that does not contain sudden changes of acceleration. If we chose a mathematical function for our speed whose second derivative is continuous, then we reduce system vibration quite a lot. One ma
Read more

Stepper motor step signal timing calculation

-
Image
While we use stepper motors in many devices, the timing of the step signals is not always well understood. Most of us can see how a fixed speed is a bad idea unless the speed of motion is really slow, but it is fixed speed what is really to generate with simple code. You just can use the Arduino Blink example to send a fixed frequency of pulses to a stepper motor driver. If too slow, just reduce the delay value. But for most real-life applications variable speed controls will perform better. These systems will speed up the motor to a given maximum speed and it will slow it down to stop at the desired step count. But understanding the math behind this process is sometimes not obvious. Let us start with the simple case of the so-called trapezoidal speed motion profile. Here motion takes place in three phases: acceleration, constant speed (cruising) and deceleration. But the point is how can our code create such a behavior. Stepper motor drivers usually accept two signals to control
Read more