Flesh out ADC bringup (hangs!)

Currently hangs waiting for cal to complete, and then again waiting for
adrdy if we skip the cal.

Should check if _any_ of the writes go through.

src/main.rs

@@ -112,7 +112,7 @@ extern crate panic_itm; // panic handler
 
 mod bsp;
 
-use cortex_m::asm::bkpt;
+use cortex_m::asm::{bkpt, delay};
 use cortex_m_rt::entry;
 
 #[entry]
@@ -133,7 +133,6 @@ fn main() -> ! {
 
     // All LEDS are outputs
     per.gpioe.moder.modify(|_, w| {
-        // NB colin: there's also a .analog() mode!
         w.moder8().output();
         w.moder9().output();
         w.moder10().output();
@@ -144,9 +143,11 @@ fn main() -> ! {
         w.moder15().output()
     });
 
-    // Configure push-button as input:
+    // Configure push-button as input;
+    // Configure PA1 as analog-in
     per.gpioa.moder.modify(|_, w| {
         w.moder0().input()
+            .moder1().analog()
     });
 
     // Configure piezo as digital input
@@ -176,22 +177,42 @@ fn main() -> ! {
     // "The software must wait for the startup time of the ADC voltage regulator
     // (T ADCVREG_STUP ) before launching a calibration or enabling the ADC."
     // 10 uS worst-case
-    // TODO: add delay
+    delay(1000); // >= 10 us
+    bkpt();
     per.adc1.cr.modify(|_, w| {
         w.advregen().set_bit()
     });
-    // TODO: delay 10 uS before starting cal
 
-    // Calibrate the ADC
+    // ADC CALIBRATION (15.3.8)
+    // 1. set ADCALDIF=0 (default)
+
+    // Start cal
     per.adc1.cr.modify(|_, w| {
         w.adcal().set_bit()
     });
-    // XXX we should probably loop until adcal is zero again, but meh.
+    // Wait for done
+    while per.adc1.cr.read().adcal().bit() { }
     
-    // TODO: set ADEN=1
+    // Enable ADC (15.3.9)
+    per.adc1.cr.modify(|_, w| {
+        w.aden().set_bit()
+    });
     // wait for ADRDY=1
-    // TODO: configure mux'ing: SQRx, JSQRx
-    // TODO: ADSTART=1
+    while per.adc1.isr.read().adrdy().bit_is_clear() { }
+
+    // Configure mux'ing: SQRx (regular conversion), JSQRx (injected conversion; don't use these)
+    // Draw from ADC1_IN2 -- PA1
+    per.adc1.sqr1.modify(|_, w| {
+        unsafe { w.sq1().bits(2) }
+    });
+    // Enable continuous mode (i.e. data will just continually appear in DR)
+    per.adc1.cfgr.modify(|_, w| {
+        w.cont().set_bit()
+    });
+    // Start ADC!
+    per.adc1.cr.modify(|_, w| {
+        w.adstart().set_bit()
+    });
 
     bkpt();