Closed
Description
Observation
Raspberry Pi pico, v1.21.0, uart.flush() takes 11ms (correct)
Raspberry Pi pico, v1.22.1/0, uart.flush() takes 785ms (way too long)
How to reproduce
import sys
import time
from machine import UART
print(sys.implementation)
bits_per_s = 9600
uart = UART(0, bits_per_s, bits=8, parity=None, stop=1, tx="GPIO0", rx="GPIO1")
text = "Hello World"
start_us = time.ticks_us()
uart.write(text)
print(f"Duration write() {time.ticks_diff(time.ticks_us(), start_us)/1000:0.2f}ms")
uart.flush()
print(f"Duration write()+flush() {time.ticks_diff(time.ticks_us(), start_us)/1000:0.2f}ms")
bits_per_char = 11 # 1(startbit)+8(bits)+1(stopbit)+1(parity)
print(f"Expected time {len(text)*bits_per_char/bits_per_s*1000:0.2f}ms")Output
(name='micropython', version=(1, 21, 0), _machine='Raspberry Pi Pico with RP2040', _mpy=4358)
Duration write() 0.16ms
Duration write()+flush() **11.41ms** (ok)
Expected time 12.60ms
(name='micropython', version=(1, 22, 0, ''), _machine='Raspberry Pi Pico with RP2040', _mpy=4614)
Duration write() 0.15ms
Duration write()+flush() **785.37ms** (way too long)
Expected time 12.60ms
(name='micropython', version=(1, 22, 1, ''), _machine='Raspberry Pi Pico with RP2040', _mpy=4614)
Duration write() 0.20ms
Duration write()+flush() **785.42ms** (way too long)
Expected time 12.60ms