Added HAL_DAC_Enable()/HAL_DAC_Is_Enabled methods to control DAC state on pin

hal/inc/dac_hal.h

@@ -43,6 +43,8 @@ extern "C" {
 #endif
 
 void HAL_DAC_Write(pin_t pin, uint16_t value);
+uint8_t HAL_DAC_Is_Enabled(pin_t pin);
+uint8_t HAL_DAC_Enable(pin_t pin, uint8_t state);
 
 #ifdef __cplusplus
 }

hal/inc/hal_dynalib_gpio.h

@@ -70,6 +70,8 @@ DYNALIB_FN(hal_gpio, HAL_Interrupts_Suspend)
 DYNALIB_FN(hal_gpio, HAL_Interrupts_Restore)
 
 DYNALIB_FN(hal_gpio, HAL_PWM_Write_With_Frequency)
+DYNALIB_FN(hal_gpio, HAL_DAC_Is_Enabled)
+DYNALIB_FN(hal_gpio, HAL_DAC_Enable)
 DYNALIB_END(hal_gpio)
 
 #endif	/* HAL_DYNALIB_GPIO_H */

hal/src/stm32f2xx/dac_hal.c

@@ -64,10 +64,6 @@ static void HAL_DAC_Init()
 
     DAC_Init(DAC_Channel_1, &DAC_InitStructure);
     DAC_Init(DAC_Channel_2, &DAC_InitStructure);
-
-    /* Enable DAC Channel1 */
-    DAC_Cmd(DAC_Channel_1, ENABLE);
-    DAC_Cmd(DAC_Channel_2, ENABLE);
 }
 
 /*
@@ -77,17 +73,19 @@ static void HAL_DAC_Init()
 void HAL_DAC_Write(pin_t pin, uint16_t value)
 {
     STM32_Pin_Info* PIN_MAP = HAL_Pin_Map();
-    if (HAL_Get_Pin_Mode(pin) != AN_OUTPUT)
-    {
-        HAL_Pin_Mode(pin, AN_OUTPUT);
-    }
 
     if (dacInitFirstTime == true)
     {
         HAL_DAC_Init();
         dacInitFirstTime = false;
     }
 
+    if (HAL_Get_Pin_Mode(pin) != AN_OUTPUT)
+    {
+        HAL_Pin_Mode(pin, AN_OUTPUT);
+        HAL_DAC_Enable(pin, 1);
+    }
+
     if (PIN_MAP[pin].dac_channel == DAC_Channel_1)
     {
         /* Set the DAC Channel1 data */
@@ -100,3 +98,27 @@ void HAL_DAC_Write(pin_t pin, uint16_t value)
         DAC_SetChannel2Data(DAC_Align_12b_R, value);
     }
 }
+
+uint8_t HAL_DAC_Is_Enabled(pin_t pin)
+{
+    STM32_Pin_Info* PIN_MAP = HAL_Pin_Map();
+    if (!dacInitFirstTime && HAL_Get_Pin_Mode(pin) == AN_OUTPUT)
+    {
+        if (DAC->CR & (DAC_CR_EN1 << PIN_MAP[pin].dac_channel))
+            return 1;
+    }
+
+    return 0;
+}
+
+uint8_t HAL_DAC_Enable(pin_t pin, uint8_t state)
+{
+    STM32_Pin_Info* PIN_MAP = HAL_Pin_Map();
+    if (!dacInitFirstTime && HAL_Get_Pin_Mode(pin) == AN_OUTPUT)
+    {
+        DAC_Cmd(PIN_MAP[pin].dac_channel, state ? ENABLE : DISABLE);
+        return 0;
+    }
+
+    return 1;
+}

hal/src/stm32f2xx/gpio_hal.c

@@ -29,6 +29,7 @@
 #include "stm32f2xx.h"
 #include <stddef.h>
 #include "hw_ticks.h"
+#include "dac_hal.h"
 
 /* Private typedef ----------------------------------------------------------*/
 
@@ -194,6 +195,12 @@ void HAL_GPIO_Write(uint16_t pin, uint8_t value)
     {
         HAL_Pin_Mode(pin, OUTPUT);
     }
+    else if (PIN_MAP[pin].pin_mode == AN_OUTPUT)
+    {
+        if (HAL_DAC_Is_Enabled(pin))
+            HAL_DAC_Enable(pin, 0);
+        HAL_Pin_Mode(pin, OUTPUT);
+    }
 
     if(value == 0)
     {
@@ -224,6 +231,22 @@ int32_t HAL_GPIO_Read(uint16_t pin)
             HAL_Pin_Mode(pin, pm);
         }
     }
+    else if (PIN_MAP[pin].pin_mode == AN_OUTPUT)
+    {
+        PinMode pm = HAL_GPIO_Recall_Pin_Mode();
+        if(pm == PIN_MODE_NONE)
+        {
+            return 0;
+        }
+        else
+        {
+            // Disable DAC
+            if (HAL_DAC_Is_Enabled(pin))
+                HAL_DAC_Enable(pin, 0);
+            // Restore pin mode
+            HAL_Pin_Mode(pin, pm);
+        }
+    }
 
     if(PIN_MAP[pin].pin_mode == OUTPUT)
     {

user/tests/wiring/adc_dac/adc_dac.cpp

@@ -111,4 +111,57 @@ test(ADC_AnalogReadOnPinWithDACShmoo) {
     }
     assertTrue(errorCount == 0);
 }
+
+test(ADC_AnalogReadOnPinWithDACMixedWithDigitalWrite) {
+    pin_t pin1 = A5;
+    pin_t pin2 = A1;
+    pinMode(pin1, INPUT);
+    pinMode(pin2, INPUT);
+
+    // Tests for issue #833 where digitalWrite after analogWrite on DAC pin
+    // causes pin to latch at last analogWrite value
+
+    // Shmoo test
+    // Set DAC/DAC2 output from 200 to 3896 (ignore non-linearity near 0V or VDD)
+    // Read back analog and compare for significant difference
+    int errorCount = 0;
+    for(int i = 200; i < 3896; i++){
+        analogWrite(DAC, i);
+        analogWrite(DAC2, 4096-i);
+        if (abs(analogRead(pin1)-i) > 200) {
+            errorCount ++;
+        }
+        else if (abs(analogRead(pin2) - 4096 + i) > 200) {
+            errorCount ++;
+        }
+    }
+    assertTrue(errorCount == 0);
+
+    digitalWrite(DAC, LOW);
+    digitalWrite(DAC2, HIGH);
+    assertFalse(abs(analogRead(pin1) - 0) > 128);
+    assertFalse(abs(analogRead(pin2) - 4096) > 128);
+
+    // Tests that digitalWrite on DAC doesn't influence analog value on DAC2
+    // and vice versa
+    errorCount = 0;
+    for(int i = 200; i < 3896; i++){
+        analogWrite(DAC, i);
+        digitalWrite(DAC2, !digitalRead(DAC2));
+        if (abs(analogRead(pin1)-i) > 200) {
+            errorCount ++;
+        }
+    }
+    assertTrue(errorCount == 0);
+
+    errorCount = 0;
+    for(int i = 200; i < 3896; i++){
+        analogWrite(DAC2, 4096-i);
+        digitalWrite(DAC, !digitalRead(DAC));
+        if (abs(analogRead(pin2) - 4096 + i) > 200) {
+            errorCount ++;
+        }
+    }
+    assertTrue(errorCount == 0);
+}
 #endif