Correctly scale analog reading per issue #4794

PaintYourDragon · web-flow · commit c3f58193ca74 · 2022-05-24T08:46:39.000-07:00
diff --git a/ports/raspberrypi/common-hal/analogio/AnalogIn.c b/ports/raspberrypi/common-hal/analogio/AnalogIn.c
@@ -65,8 +65,8 @@ uint16_t common_hal_analogio_analogin_get_value(analogio_analogin_obj_t *self) {
     adc_select_input(self->pin->number - ADC_FIRST_PIN_NUMBER);
     uint16_t value = adc_read();
 
-    // Map value to from 12 to 16 bits
-    return value << 4;
+    // Stretch 12-bit ADC reading to 16-bit range
+    return (value << 4) | (value >> 8);
 }
 
 float common_hal_analogio_analogin_get_reference_voltage(analogio_analogin_obj_t *self) {

Original file line number	Diff line number	Diff line change
`@@ -65,8 +65,8 @@ uint16_t common_hal_analogio_analogin_get_value(analogio_analogin_obj_t *self) {`
`65`	`65`	`adc_select_input(self->pin->number - ADC_FIRST_PIN_NUMBER);`
`66`	`66`	`uint16_t value = adc_read();`
`67`	`67`
`68`		`- // Map value to from 12 to 16 bits`
`69`		`- return value << 4;`
	`68`	`+ // Stretch 12-bit ADC reading to 16-bit range`
	`69`	`+ return (value << 4) \| (value >> 8);`
`70`	`70`	`}`
`71`	`71`
`72`	`72`	`float common_hal_analogio_analogin_get_reference_voltage(analogio_analogin_obj_t *self) {`