2019-08-09 17:50:30 +00:00
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From ca04bf45b9d33ebc574d2fc6af5cca9a9e4ffc89 Mon Sep 17 00:00:00 2001
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2019-07-09 18:32:28 +00:00
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From: Matthias Reichl <hias@horus.com>
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Date: Wed, 9 Jan 2019 14:51:01 +0100
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2019-08-09 17:50:30 +00:00
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Subject: [PATCH 291/773] gpio-ir: change default pull configuration to up
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2019-07-09 18:32:28 +00:00
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IR receivers like the TSOP series from Vishay and compatible ones
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have active-low open collector outputs with an internal pull up of
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about 30k (according to the TSOP datasheets).
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Activating a pull-down resistor on the GPIO will make it work against
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the pull-up in the IR receiver and brings the idle input voltage down
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to about 1.9V (measured on a RPi3B+ with a TSOP4438). While that's
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usually enough to make the RPi see a high signal it's certainly not
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optimal and may even fail when using an IR receiver with a weaker pull-up.
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Switching the default GPIO pull to "up" results in an input voltage
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level of about 3.3V and ensures that an idle state (high signal) will
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be detected if no IR receiver is attached.
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Signed-off-by: Matthias Reichl <hias@horus.com>
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---
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arch/arm/boot/dts/overlays/README | 2 +-
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arch/arm/boot/dts/overlays/gpio-ir-overlay.dts | 2 +-
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2 files changed, 2 insertions(+), 2 deletions(-)
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--- a/arch/arm/boot/dts/overlays/README
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+++ b/arch/arm/boot/dts/overlays/README
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@@ -611,7 +611,7 @@ Load: dtoverlay=gpio-ir,<param>=<val>
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Params: gpio_pin Input pin number. Default is 18.
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gpio_pull Desired pull-up/down state (off, down, up)
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- Default is "down".
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+ Default is "up".
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rc-map-name Default rc keymap (can also be changed by
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ir-keytable), defaults to "rc-rc6-mce"
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--- a/arch/arm/boot/dts/overlays/gpio-ir-overlay.dts
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+++ b/arch/arm/boot/dts/overlays/gpio-ir-overlay.dts
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@@ -30,7 +30,7 @@
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gpio_ir_pins: gpio_ir_pins@12 {
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brcm,pins = <18>; // pin 18
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brcm,function = <0>; // in
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- brcm,pull = <1>; // down
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+ brcm,pull = <2>; // up
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};
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};
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};
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