Move the encoder mode register write to counter.rs, document

src/counter.rs

@@ -8,6 +8,16 @@ pub struct Counter<PINS> {
 
 impl<PINS> Counter<PINS> {
     pub fn new(qei: Qei<TIM1, PINS>) -> Self {
+        unsafe {
+            // TODO(bschwind) - Expose this functionality with a safe interface
+            //                  in stm32f4xx-hal.
+            // Change the mode of the QEI decoder to mode 1:
+            // Counter counts up/down on TI2FP1 edge depending on TI1FP2 level.
+            // Or in layman's terms, the encoder counts up and down on encoder
+            // pin A edges, while referencing the state of encoder pin B.
+            (*TIM1::ptr()).smcr.write(|w| w.sms().encoder_mode_1());
+        }
+
         let last_count = qei.count();
         Counter { qei, last_count }
     }

src/main.rs

@@ -18,7 +18,6 @@ use cortex_m_rt::entry;
 use embedded_hal::digital::v2::OutputPin;
 use hal::{
     otg_fs::{UsbBus, USB},
-    pac::TIM1,
     prelude::*,
     pwm,
     qei::Qei,
@@ -119,16 +118,6 @@ fn main() -> ! {
     let rotary_encoder_pins = (gpioa.pa8.into_alternate_af1(), gpioa.pa9.into_alternate_af1());
     let rotary_encoder = Qei::new(rotary_encoder_timer, rotary_encoder_pins);
 
-    unsafe {
-        // Change the polarity of the encoder to Falling edge - it could better align with the detents of our volume dial.
-        // Taken form https://github.com/stm32-rs/stm32f4xx-hal/issues/410
-        // (*TIM1::ptr()).ccer.write(|w| w.cc1p().set_bit().cc2p().set_bit());
-
-        // Change the mode of the QEI decoder to mode 1:
-        // Counter counts up/down on TI2FP1 edge depending on TI1FP2 level.
-        (*TIM1::ptr()).smcr.write(|w| w.sms().encoder_mode_1());
-    }
-
     let mut counter = Counter::new(rotary_encoder);
 
     let button_pin = gpioa.pa10.into_pull_up_input();