Resurrect ADC support.

Standard refactoring: add series headers for F1 and F2, along with
series adc.c files. There are some issues relating to adc_extsel_event
to hammer out later, but this will do for now.

We also add some new portability interfaces to libmaple/adc.h in order
for Wirish to use the same code to initialize the ADCs at init() time.

As usual, F1 is untested.

Signed-off-by: Marti Bolivar <mbolivar@leaflabs.com>

4 files changed, 59 insertions, 39 deletions

diff --git a/wirish/boards.cpp b/wirish/boards.cpp
index 04b359f..54807d3 100644
--- a/wirish/boards.cpp
+++ b/wirish/boards.cpp
@@ -54,6 +54,7 @@
 static void setup_flash(void);
 static void setup_clocks(void);
 static void setup_nvic(void);
+static void setup_adcs(void);
 
 /*
  * Exported functions
@@ -65,7 +66,7 @@ void init(void) {
     setup_nvic();
     systick_init(SYSTICK_RELOAD_VAL);
     wirish::priv::board_setup_gpio();
-    wirish::priv::board_setup_adc();
+    setup_adcs();
     wirish::priv::board_setup_timers();
     wirish::priv::board_setup_usb();
     boardInit();
@@ -124,7 +125,7 @@ static void setup_clocks(void) {
 
     // Configure AHBx, APBx, etc. prescalers and the main PLL.
     wirish::priv::board_setup_clock_prescalers();
-    rcc_configure_pll(&wirish::priv::board_pll_cfg);
+    rcc_configure_pll(&wirish::priv::w_board_pll_cfg);
 
     // Enable the PLL, and wait until it's ready.
     rcc_turn_on_clk(RCC_CLK_PLL);
@@ -146,3 +147,13 @@ static void setup_nvic(void) {
 #error "You must select a base address for the vector table."
 #endif
 }
+
+static void adc_default_config(const adc_dev *dev) {
+    adc_enable_single_swstart(dev);
+    adc_set_sample_rate(dev, wirish::priv::w_adc_smp);
+}
+
+static void setup_adcs(void) {
+    adc_set_prescaler(wirish::priv::w_adc_pre);
+    adc_foreach(adc_default_config);
+}
diff --git a/wirish/boards_private.h b/wirish/boards_private.h
index a4101c9..e32f298 100644
--- a/wirish/boards_private.h
+++ b/wirish/boards_private.h
@@ -28,11 +28,18 @@
  * @file wirish/boards_private.h
  * @author Marti Bolivar <mbolivar@leaflabs.com>
  * @brief Private board support header.
+ *
+ * This file declares chip-specific variables and functions which
+ * determine how init() behaves. It is not part of the public Wirish
+ * API, and can change without notice.
  */
 
 #ifndef _WIRISH_BOARDS_PRIVATE_H_
 #define _WIRISH_BOARDS_PRIVATE_H_
 
+#include <libmaple/rcc.h>
+#include <libmaple/adc.h>
+
 namespace wirish {
     namespace priv {
 
@@ -40,7 +47,9 @@ namespace wirish {
          * Chip-specific initialization data
          */
 
-        extern rcc_pll_cfg board_pll_cfg;
+        extern rcc_pll_cfg w_board_pll_cfg;
+        extern adc_prescaler w_adc_pre;
+        extern adc_smp_rate w_adc_smp;
 
         /*
          * Chip-specific initialization routines and helper functions.
@@ -49,7 +58,6 @@ namespace wirish {
         void board_reset_pll(void);
         void board_setup_clock_prescalers(void);
         void board_setup_gpio(void);
-        void board_setup_adc(void);
         void board_setup_timers(void);
         void board_setup_usb(void);
 
diff --git a/wirish/stm32f1/boards_setup.cpp b/wirish/stm32f1/boards_setup.cpp
index 4ee292a..8e16009 100644
--- a/wirish/stm32f1/boards_setup.cpp
+++ b/wirish/stm32f1/boards_setup.cpp
@@ -28,11 +28,15 @@
  * @file wirish/stm32f1/boards_setup.cpp
  * @author Marti Bolivar <mbolivar@leaflabs.com>
  * @brief STM32F1 chip setup.
+ *
+ * This file controls how init() behaves on the STM32F1. Be very
+ * careful when changing anything here. Many of these values depend
+ * upon each other.
  */
 
-#include <libmaple/rcc.h>
+#include "boards_private.h"
+
 #include <libmaple/gpio.h>
-#include <libmaple/adc.h>
 #include <libmaple/timer.h>
 #include <libmaple/usb_cdcacm.h>
 
@@ -45,12 +49,11 @@ namespace wirish {
     namespace priv {
 
         static stm32f1_rcc_pll_data pll_data = {RCC_PLLMUL_9};
-        rcc_pll_cfg board_pll_cfg = {RCC_PLLSRC_HSE, &pll_data};
+        rcc_pll_cfg w_board_pll_cfg = {RCC_PLLSRC_HSE, &pll_data};
+        adc_prescaler w_adc_pre = ADC_PRE_PCLK2_DIV_6;
+        adc_smp_rate w_adc_smp = ADC_SMPR_55_5;
 
-#if 0
-        static void config_adc(const adc_dev* dev);
         static void config_timer(timer_dev*);
-#endif
 
         void board_reset_pll(void) {
             // TODO
@@ -69,17 +72,8 @@ namespace wirish {
             afio_init();
         }
 
-        void board_setup_adc(void) {
-#if 0
-            rcc_set_prescaler(RCC_PRESCALER_ADC, RCC_ADCPRE_PCLK_DIV_6);
-            adc_foreach(config_adc);
-#endif
-        }
-
         void board_setup_timers(void) {
-#if 0
             timer_foreach(config_timer);
-#endif
         }
 
         void board_setup_usb(void) {
@@ -92,19 +86,8 @@ namespace wirish {
          * Auxiliary routines
          */
 
-#if 0
-        static void config_adc(const adc_dev *dev) {
-            adc_init(dev);
-
-            adc_set_extsel(dev, ADC_SWSTART);
-            adc_set_exttrig(dev, true);
-
-            adc_enable(dev);
-            adc_calibrate(dev);
-            adc_set_sample_rate(dev, ADC_SMPR_55_5);
-        }
-
         static void config_timer(timer_dev *dev) {
+#if 0
             timer_adv_reg_map *regs = (dev->regs).adv;
             const uint16 full_overflow = 0xFFFF;
             const uint16 half_duty = 0x8FFF;
@@ -135,7 +118,7 @@ namespace wirish {
             }
 
             timer_resume(dev);
-        }
 #endif
+        }
     }
 }
diff --git a/wirish/stm32f2/boards_setup.cpp b/wirish/stm32f2/boards_setup.cpp
index b3c690c..e1bf1fd 100644
--- a/wirish/stm32f2/boards_setup.cpp
+++ b/wirish/stm32f2/boards_setup.cpp
@@ -28,11 +28,18 @@
  * @file wirish/stm32f2/boards_setup.cpp
  * @author Marti Bolivar <mbolivar@leaflabs.com>
  * @brief STM32F2 chip setup.
+ *
+ * This file controls how init() behaves on the STM32F2. Be very
+ * careful when changing anything here. Many of these values depend
+ * upon each other.
  */
 
-#include <libmaple/rcc.h>
+#include "boards_private.h"
+
 #include <libmaple/gpio.h>
+#include <wirish/wirish_types.h>
 
+// PLL configuration for 25 MHz external oscillator --> 120 MHz SYSCLK.
 #define PLL_Q 5
 #define PLL_P 2
 #define PLL_N 240
@@ -41,7 +48,18 @@ static stm32f2_rcc_pll_data pll_data = {PLL_Q, PLL_P, PLL_N, PLL_M};
 
 namespace wirish {
     namespace priv {
-        rcc_pll_cfg board_pll_cfg = {RCC_PLLSRC_HSE, &pll_data};
+        // PLL clocked off of HSE, with above configuration data.
+        rcc_pll_cfg w_board_pll_cfg = {RCC_PLLSRC_HSE, &pll_data};
+        // As f_APB2 = 60 MHz (see board_setup_clock_prescalers),
+        // we need f_ADC = f_PCLK2 / 2 to get the (maximum)
+        // f_ADC = 30 MHz.
+        adc_prescaler w_adc_pre = ADC_PRE_PCLK2_DIV_2;
+        // With clocks as specified here (i.e. f_ADC = 30 MHz), this
+        // ADC sample rate allows for error less than 1/4 LSB with a
+        // 50 KOhm input impedance, assuming an internal sample and
+        // hold capacitance C_ADC at most 8.8 pF. See Equation 1 and
+        // Table 61 in the F2 datasheet for more details.
+        adc_smp_rate w_adc_smp = ADC_SMPR_144;
 
         void board_reset_pll(void) {
             // Set PLLCFGR to its reset value.
@@ -49,8 +67,13 @@ namespace wirish {
         }
 
         void board_setup_clock_prescalers(void) {
+            // With f_SYSCLK = 120 MHz (as determined by board_pll_cfg),
+            //
+            // f_AHB = f_SYSCLK / 1 = 120 MHz
             rcc_set_prescaler(RCC_PRESCALER_AHB, RCC_AHB_SYSCLK_DIV_1);
+            // f_APB1 = f_AHB / 4 = 30 MHz
             rcc_set_prescaler(RCC_PRESCALER_APB1, RCC_APB1_HCLK_DIV_4);
+            // f_APB2 = f_AHB / 2 = 60 MHz
             rcc_set_prescaler(RCC_PRESCALER_APB2, RCC_APB2_HCLK_DIV_2);
         }
 
@@ -58,10 +81,6 @@ namespace wirish {
             gpio_init_all();
         }
 
-        void board_setup_adc(void) {
-            // TODO
-        }
-
         void board_setup_timers(void) {
             // TODO
         }
@@ -72,4 +91,3 @@ namespace wirish {
 
     }
 }
-