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delay 100us for analog voltage to stabilize

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.. otherwise, depending on the prior state of the pin as a digital
input, the value read could be 20% low.
This commit is contained in:
Jeff Epler 2022-11-08 10:42:14 -06:00
parent 09f6919c93
commit 7f36a365cf
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GPG Key ID: D5BF15AB975AB4DE
1 changed files with 2 additions and 0 deletions
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ports/raspberrypi/common-hal/analogio/AnalogIn.c
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@ -26,6 +26,7 @@
#include "common-hal/analogio/AnalogIn.h" #include "common-hal/analogio/AnalogIn.h"
#include "shared-bindings/analogio/AnalogIn.h" #include "shared-bindings/analogio/AnalogIn.h"
#include "shared-bindings/microcontroller/__init__.h"
#include "shared-bindings/microcontroller/Pin.h" #include "shared-bindings/microcontroller/Pin.h"
#include "py/runtime.h" #include "py/runtime.h"
#include "supervisor/shared/translate/translate.h" #include "supervisor/shared/translate/translate.h"
@ -81,6 +82,7 @@ uint16_t common_hal_analogio_analogin_get_value(analogio_analogin_obj_t *self) {
uint32_t old_ctrl = iobank0_hw->io[self->pin->number].ctrl; uint32_t old_ctrl = iobank0_hw->io[self->pin->number].ctrl;
adc_gpio_init(self->pin->number); adc_gpio_init(self->pin->number);
adc_select_input(self->pin->number - ADC_FIRST_PIN_NUMBER); adc_select_input(self->pin->number - ADC_FIRST_PIN_NUMBER);
common_hal_mcu_delay_us(100);
value = adc_read(); value = adc_read();
gpio_init(self->pin->number); gpio_init(self->pin->number);
padsbank0_hw->io[self->pin->number] = old_pad; padsbank0_hw->io[self->pin->number] = old_pad;