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Reset the Elecrow's GT911 the way Elecrow's own V3.0 example does (0.2.96, firmware 0.2.82)
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The 2 ms reset of ESPHome's expander support (0.2.81) left the chip silent: "Calibration error" with the PCA9557
answering at 0x18. A component of smart_display's (elecrow_touch_reset.h, setup priority 700: after the I2C bus,
before the GT911 driver) writes the expander as Elecrow's V3.0 ESPHome example does: every pin an output and low,
20 ms, the reset released, 100 ms, the interrupt line back to an input. The driver's reset and interrupt pins are gone.
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Xandrossian
2026-09-21 13:30:41 -07:00
parent da28d19961
commit 4ec8c7a935
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@@ -41,12 +41,13 @@ suits a screen that stands further away.
The GT911 is polled every 20 ms over I2C at 400 kHz. The **V3.0** has a PCA9557 I/O expander (I2C 0x18) on the
GT911's reset (IO0) and interrupt (IO1) lines, and a unit tested here kept its GT911 in reset until something drove
them (`touchscreen is marked FAILED: Calibration error` in the log, firmware 0.2.79 and 0.2.80). The board file
(firmware 0.2.81) declares the expander as ESPHome's `pca9554` (the same register map) and hands the GT911 driver its
reset and interrupt pins on it: the driver runs Elecrow's own sequence, reset low with the interrupt line low, reset
high, then 56 ms, which also fixes the address at 0x5D. A V2.0 board without the expander boots its GT911 by the
pull-up as before; the expander's setup fails there, harmlessly, and the driver tries 0x14 by itself when 0x5D does
not answer, so no address override is ever needed.
them (`touchscreen is marked FAILED: Calibration error` in the log, firmware 0.2.79 to 0.2.81; 0.2.81 tried ESPHome's
own expander support, whose 2 ms reset pulse the chip ignored). `smart_display: elecrow_touch_reset` (firmware 0.2.82,
`components/smart_display/elecrow_touch_reset.h`) runs the sequence of Elecrow's V3.0 ESPHome example before the
driver looks for the chip: every expander pin an output and low (the reset held, the interrupt line low so the chip
takes address 0x5D), 20 ms, the reset released, 100 ms, the interrupt line back to an input. The log says `GT911 reset
through the PCA9557`. A V2.0 board without the expander boots its GT911 by the pull-up as before (the writes fail, the
log says so), and the driver tries 0x14 by itself when 0x5D does not answer, so no address override is ever needed.
The bus is scanned at boot. For a diagnosis, give the screen `logger: level: DEBUG` in its Override YAML (Screen
settings → Override YAML) and read its log: the scan lists 0x18 (the expander) and 0x5D or 0x14 (the GT911), and the