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# Test machine.UART transmission.
# Does not require any external connections.
try:
from machine import UART
except ImportError:
print("SKIP")
raise SystemExit
import time, sys
initial_delay_ms = 0
bit_margin = 0
timing_margin_us = 100
# Configure pins based on the target.
if "alif" in sys.platform:
uart_id = 1
pins = {}
bit_margin = 1
elif "esp32" in sys.platform:
uart_id = 1
pins = {}
timing_margin_us = 400
elif "mimxrt" in sys.platform:
uart_id = 1
pins = {}
initial_delay_ms = 20 # UART sends idle frame after init, so wait for that
bit_margin = 1
elif "pyboard" in sys.platform:
uart_id = 4
pins = {}
initial_delay_ms = 50 # UART sends idle frame after init, so wait for that
bit_margin = 1 # first start-bit must wait to sync with the UART clock
elif "rp2" in sys.platform:
uart_id = 0
pins = {"tx": "GPIO0", "rx": "GPIO1"}
timing_margin_us = 180
elif "samd" in sys.platform:
uart_id = 2
pins = {"tx": "D1", "rx": "D0"}
timing_margin_us = 300
bit_margin = 1
else:
print("SKIP")
raise SystemExit
# Test that write+flush takes the expected amount of time to execute.
for bits_per_s in (2400, 9600, 115200):
text = "Hello World"
uart = UART(uart_id, bits_per_s, bits=8, parity=None, stop=1, **pins)
time.sleep_ms(initial_delay_ms)
start_us = time.ticks_us()
uart.write(text)
uart.flush()
duration_us = time.ticks_diff(time.ticks_us(), start_us)
# 1(startbit) + 8(bits) + 1(stopbit) + 0(parity)
bits_per_char = 10
expect_us = (len(text)) * bits_per_char * 1_000_000 // bits_per_s
delta_us = abs(duration_us - expect_us)
margin_us = timing_margin_us + bit_margin * 1_000_000 // bits_per_s
print(bits_per_s, delta_us <= margin_us or delta_us)
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