esp32/machine_uart: Change sendbreak() implementation to simply pull the pin low for the break period
#17698
+22
−31
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Signed-off-by: Damien George <damien@micropython.org>
This is no longer needed, the esp32 port can now pass this test using just a single UART. Signed-off-by: Damien George <damien@micropython.org>
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@hmaerki FYI this should fix the final issue with octoprobe/testbed_micropython#36 |
Codecov ReportAll modified and coverable lines are covered by tests ✅
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## master #17698 +/- ##
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Coverage 98.44% 98.44%
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Files 171 171
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Summary
Currently,
UART.sendbreak()on esp32 will reconfigure the UART to a slower baudrate and send out a null byte, to synthesise a break condition. That's not great because it changes the baudrate of the RX path as well, which could miss incoming bytes while sending the break.This PR changes the sendbreak implementation to just reconfigure the TX pin as GPIO in output mode, and hold the pin low for the required duration.
Testing
Existing test is updated (simplified) and works well on ESP32_GENERIC.
Also tested that RPI_PICO_W still passes this test.
Trade-offs and Alternatives
There's
uart_write_bytes_with_break()but that requires at least 1 byte to be sent before the break, so we can't use that.There's also the lower level
uart_hal_tx_break()but I'm not sure how to use that properly in conjunction with the higher level driver.