Pico 1-W - slow(er) response to first network packet after a pause.

[mungewell]

I am (as usual) pushing the Pico to it's limits...

This time I am working on a NTP server and have discovered that the first network packet seems to be delivered 'late' to my self.sock.recvfrom() call, meaning that the resultant time delivered to the client is less accurate. Bug write-up here:
riblettmj/TimePico#7

I don't have confirmation that it's the IC in the Pico 1-W, but I suspect that this might some power save mode enabled by default. Looking at the Pico-SDK I don't see any methods for controlling the PowerSave.
https://github.com/raspberrypi/pico-sdk/blob/master/src/rp2_common/pico_cyw43_driver/cyw43_driver.c

But this 3rd party documentation of the driver suggests that it should be possible.
https://github.com/georgerobotics/cyw43-driver/blob/bed438f119cfba03f75957fceb6a5623ef95e6d9/src/cyw43_ll.h#L184

#define CYW43_NO_POWERSAVE_MODE           (0) ///< No Powersave mode
#define CYW43_PM1_POWERSAVE_MODE          (1) ///< Powersave mode on specified interface without regard for throughput reduction
#define CYW43_PM2_POWERSAVE_MODE          (2) ///< Powersave mode on specified interface with High throughput

Is there anyway I 'fake' these calls from microPython, or do I need to patch SDK and rebuild?

Any other suggestions on what might be occuring?

[mungewell]

For reference I am testing with:

MicroPython v1.29.0 on 2026-08-24; Raspberry Pi Pico W with RP2040

[mungewell]

Confirmed that PowerManagment was set to '2', and can be set '0' for optimum responses

[timepico] psuedo WL_IRQ monitor enabled on GPIO26
[timepico] PPS PIO/DMA enabled on GPIO 16
[timepico] WLAN PM before: 0xa11142
[timepico] WLAN PM after: 0xa11140
[timepico] Connecting WiFi STA...
[timepico] WiFi STA up: ('192.168.1.101', '255.255.255.0', '192.168.1.1', '192.168.1.1')
[timepico] NTP server listening on UDP/123
[timepico] Stabilized: GPS+PPS locked for 30 seconds -> eligible voter / can serve if stable.

$ for i in {1..5};do ntpdig -p 1 192.168.1.101;sleep 1; done 
2026-10-27 20:16:07.151951 (-0600) -0.000954 +/- 0.000962 192.168.1.101 s1 no-leap
2026-10-27 20:16:08.263971 (-0600) -0.001253 +/- 0.000958 192.168.1.101 s1 no-leap
2026-10-27 20:16:09.374429 (-0600) -0.001172 +/- 0.001134 192.168.1.101 s1 no-leap
2026-10-27 20:16:10.483662 (-0600) -0.001125 +/- 0.001100 192.168.1.101 s1 no-leap
2026-10-27 20:16:11.593167 (-0600) -0.001608 +/- 0.001535 192.168.1.101 s3 no-leap

Quick code patch:

    if NET_MODE == "wifi":
        wlan = network.WLAN(network.STA_IF)
        wlan.active(True)

        # disable powersave
        log("WLAN PM before:", hex(wlan.config('pm')))
        wlan.config(pm=0xA11140)
        log("WLAN PM after:", hex(wlan.config('pm')))