Correctly scale analog reading per issue #4794

PaintYourDragon · web-flow · commit eefba1664411 · 2022-05-24T08:40:51.000-07:00
diff --git a/ports/atmel-samd/common-hal/analogio/AnalogIn.c b/ports/atmel-samd/common-hal/analogio/AnalogIn.c
@@ -123,8 +123,8 @@ uint16_t common_hal_analogio_analogin_get_value(analogio_analogin_obj_t *self) {
     adc_sync_read_channel(&adc, self->channel, ((uint8_t *)&value), 2);
 
     adc_sync_deinit(&adc);
-    // Shift the value to be 16 bit.
-    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
`@@ -123,8 +123,8 @@ uint16_t common_hal_analogio_analogin_get_value(analogio_analogin_obj_t *self) {`
`123`	`123`	`adc_sync_read_channel(&adc, self->channel, ((uint8_t *)&value), 2);`
`124`	`124`
`125`	`125`	`adc_sync_deinit(&adc);`
`126`		`- // Shift the value to be 16 bit.`
`127`		`- return value << 4;`
	`126`	`+ // Stretch 12-bit ADC reading to 16-bit range`
	`127`	`+ return (value << 4) \| (value >> 8);`
`128`	`128`	`}`
`129`	`129`
`130`	`130`	`float common_hal_analogio_analogin_get_reference_voltage(analogio_analogin_obj_t *self) {`