From 0d440118bd4e1ba64f92d3636302fbddeac5bef6 Mon Sep 17 00:00:00 2001
From: Marti Bolivar <mbolivar@leaflabs.com>
Date: Fri, 18 Feb 2011 04:00:00 -0500
Subject: Basic DAC functionality (high-density devices only).

---
 examples/test-dac.cpp | 50 +++++++++++++++++++++-----------------------------
 libmaple/dac.c        | 16 +++++++---------
 libmaple/dac.h        |  2 ++
 libmaple/rcc.c        |  2 +-
 notes/dac.txt         | 24 +++++++++++++++++++-----
 5 files changed, 50 insertions(+), 44 deletions(-)

diff --git a/examples/test-dac.cpp b/examples/test-dac.cpp
index 65496f4..3a699e2 100644
--- a/examples/test-dac.cpp
+++ b/examples/test-dac.cpp
@@ -5,49 +5,41 @@
 #include "gpio.h"
 #include "dac.h"
 
-#define LED_PIN  23 // hack for maple native
-#define DISC_PIN 14 // hack for USB on native
-
-int toggle = 0;
 uint16 count = 0;
 
 void setup() {
 
-   pinMode(LED_PIN, OUTPUT);
-   pinMode(DISC_PIN, OUTPUT);
-   digitalWrite(DISC_PIN,1);
-   digitalWrite(LED_PIN,1);
+    pinMode(BOARD_LED_PIN, OUTPUT);
+    digitalWrite(BOARD_LED_PIN,1);
 
-   Serial1.begin(9600);
-   Serial1.println("Hello World!");
+    Serial1.begin(9600);
+    Serial1.println("**** Beginning DAC test");
 
-   Serial1.print("Init... ");
-   dac_init();
-   Serial1.println("Done.");
+    Serial1.print("Init... ");
+    dac_init();
+    Serial1.println("Done.");
 }
 
 void loop() {
-   digitalWrite(LED_PIN, toggle);
-   toggle ^= 1;
-   delay(100);
-
-   count += 100;
+    toggleLED();
+    delay(100);
 
-   if(count > 4095) {
-      count = 0;
-   }
+    count += 100;
+    if(count > 4095) {
+        count = 0;
+    }
 
-   dac_write(1, 2048);
-   dac_write(2, count);
+    dac_write(1, 2048);
+    dac_write(2, count);
 }
 
 int main(void) {
-   init();
-   setup();
+    init();
+    setup();
 
-   while (1) {
-      loop();
-   }
-   return 0;
+    while (1) {
+        loop();
+    }
+    return 0;
 }
 
diff --git a/libmaple/dac.c b/libmaple/dac.c
index 7f6101d..63a96ac 100644
--- a/libmaple/dac.c
+++ b/libmaple/dac.c
@@ -31,12 +31,11 @@
  * @brief DAC peripheral routines.
  */
 
-/* Only one, so global to this file */
-DAC_Map *dac = (DAC_Map*)(DAC_BASE);
-
 /* This numbering follows the registers (1-indexed) */
-#define DAC_CHA     1
-#define DAC_CHB     2
+#define DAC_CH1     1
+#define DAC_CH2     2
+
+DAC_Map *dac = (DAC_Map*)(DAC_BASE);
 
 /* Sets up the DAC peripheral */
 void dac_init(void) {
@@ -49,16 +48,15 @@ void dac_init(void) {
 
     /* Then do register stuff.  Default does no triggering, and
      * buffered output, so all good. */
-    dac->CR |= DAC_CR_EN1;
-    dac->CR |= DAC_CR_EN2;
+    dac->CR = DAC_CR_EN1 | DAC_CR_EN2;
 }
 
 void dac_write(uint8 chan, uint16 val) {
     switch(chan) {
-    case DAC_CHA:
+    case DAC_CH1:
         dac->DHR12R1 = 0x0FFF & val;
         break;
-    case DAC_CHB:
+    case DAC_CH2:
         dac->DHR12R2 = 0x0FFF & val;
         break;
     default:
diff --git a/libmaple/dac.h b/libmaple/dac.h
index 9c84f2e..340a49a 100644
--- a/libmaple/dac.h
+++ b/libmaple/dac.h
@@ -55,6 +55,8 @@ typedef struct {
     volatile uint32 DOR2;
 } DAC_Map;
 
+/* There's only one DAC, so expose it. */
+extern DAC_Map *dac;
 
 // And here are the register bit ranges
 #define DAC_CR_EN1      BIT(0)
diff --git a/libmaple/rcc.c b/libmaple/rcc.c
index 313eaf7..6905c22 100644
--- a/libmaple/rcc.c
+++ b/libmaple/rcc.c
@@ -70,7 +70,7 @@ static const struct rcc_dev_info rcc_dev_table[] = {
     [RCC_SPI1]   = { .clk_domain = APB2, .line_num = 12 },
     [RCC_SPI2]   = { .clk_domain = APB1, .line_num = 14 },
     [RCC_FSMC]   = { .clk_domain = AHB,  .line_num = 8 }, // High-density only
-    [RCC_DAC]    = { .clk_domain = APB1, .line_num = 9 }, // High-density only
+    [RCC_DAC]    = { .clk_domain = APB1, .line_num = 29 }, // High-density only
     [RCC_DMA1]   = { .clk_domain = AHB,  .line_num = 0 },
     [RCC_DMA2]   = { .clk_domain = AHB,  .line_num = 1 }, // High-density only
 };
diff --git a/notes/dac.txt b/notes/dac.txt
index 9df0782..d027402 100644
--- a/notes/dac.txt
+++ b/notes/dac.txt
@@ -13,11 +13,25 @@ control, and timer events. We'll just use software triggering for now.
 
 There is (obviously) DMA support for DAC output.
 
-There are noise output and triangle wave output features with variable
-amplitude.
-
-There are many additional modes to tigger output to both channels at the same
-time.
+There are noise (via LFSR) output and triangle wave output features
+with variable amplitude.
+
+There are eleven modes to trigger output to both channels at the same
+time, as follows:
+
+    - Independent trigger:
+                  (1) No wave generation
+                  (2) Same LFSR
+                  (3) Different LFSR
+                  (4) Same triangle
+                  (5) Different triangle
+    - (6) Simultaneous software start
+    - Simultaneous trigger:
+                   (7) Without wave generation
+                   (8) Same LFSR
+                   (9) Different LFSR
+                   (10) Same triangle
+                   (11) Different triangle
 
 Buffering will be enabled by default.
 
-- 
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