10000 esp8266/esp_mphal.h: Fix I2C glitching by using input mode for od_high. · micropython/micropython@033c32e · GitHub
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dpgeorgedpgeorge
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esp8266/esp_mphal.h: Fix I2C glitching by using input mode for od_high.
Certain pins (eg 4 and 5) seem to behave differently at the hardware level when in open-drain mode: they glitch when set "high" and drive the pin active high for a brief period before disabling the output driver. To work around this make the pin an input to let it float high.
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‎ports/esp8266/esp_mphal.h

Lines changed: 1 addition & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -86,7 +86,7 @@ void mp_hal_pin_open_drain(mp_hal_pin_obj_t pin);
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} while (0)
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#define mp_hal_pin_od_high(p) do { \
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if ((p) == 16) { WRITE_PERI_REG(RTC_GPIO_ENABLE, (READ_PERI_REG(RTC_GPIO_ENABLE) & ~1)); } \
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else { gpio_output_set(1 << (p), 0, 1 << (p), 0); } \
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else { gpio_output_set(0, 0, 0, 1 << (p)); /* set as input to avoid glitches */ } \
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} while (0)
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#define mp_hal_pin_read(p) pin_get(p)
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#define mp_hal_pin_write(p, v) pin_set((p), (v))

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