Correctly scale analog reading per issue #4794

PaintYourDragon · web-flow · commit 44b31b098e12 · 2022-05-24T08:44:09.000-07:00
diff --git a/ports/mimxrt10xx/common-hal/analogio/AnalogIn.c b/ports/mimxrt10xx/common-hal/analogio/AnalogIn.c
@@ -81,8 +81,8 @@ uint16_t common_hal_analogio_analogin_get_value(analogio_analogin_obj_t *self) {
 
     }
 
-    // Shift the value to be 16 bit
-    return ADC_GetChannelConversionValue(self->pin->adc, ADC_CHANNEL_GROUP) << 4;
+    // Stretch 12-bit ADC reading to 16 bits via 24-bit interim result
+    return (ADC_GetChannelConversionValue(self->pin->adc, ADC_CHANNEL_GROUP) * 0x1001) >> 8;
 }
 
 float common_hal_analogio_analogin_get_reference_voltage(analogio_analogin_obj_t *self) {

Original file line number	Diff line number	Diff line change
`@@ -81,8 +81,8 @@ uint16_t common_hal_analogio_analogin_get_value(analogio_analogin_obj_t *self) {`
`81`	`81`
`82`	`82`	`}`
`83`	`83`
`84`		`- // Shift the value to be 16 bit`
`85`		`- return ADC_GetChannelConversionValue(self->pin->adc, ADC_CHANNEL_GROUP) << 4;`
	`84`	`+ // Stretch 12-bit ADC reading to 16 bits via 24-bit interim result`
	`85`	`+ return (ADC_GetChannelConversionValue(self->pin->adc, ADC_CHANNEL_GROUP) * 0x1001) >> 8;`
`86`	`86`	`}`
`87`	`87`
`88`	`88`	`float common_hal_analogio_analogin_get_reference_voltage(analogio_analogin_obj_t *self) {`