Merge pull request #246 from sparkfun/adcDifferential

Author: Owen

cores/arduino/ard_sup/analog/ap3_analog.cpp

@@ -159,7 +159,27 @@ uint16_t analogRead(uint8_t pinNumber)
         {
             if (ap3_analog_configure_map[indi].isAnalog == false)
             {
-                if (ap3_set_pin_to_analog(pinNumber) != AP3_OK)
+                if (padNumber == AP3_ADC_DIFF0_PAD)
+                {
+                    ap3_err_t retval = AP3_ERR;
+                    retval = ap3_set_pin_to_analog(ap3_gpio_pad2pin(12));
+                    retval = ap3_set_pin_to_analog(ap3_gpio_pad2pin(13));
+                    if (retval != AP3_OK)
+                    {
+                        return 0; //Error
+                    }
+                }
+                else if (padNumber == AP3_ADC_DIFF1_PAD)
+                {
+                    ap3_err_t retval = AP3_ERR;
+                    retval = ap3_set_pin_to_analog(ap3_gpio_pad2pin(14));
+                    retval = ap3_set_pin_to_analog(ap3_gpio_pad2pin(15));
+                    if (retval != AP3_OK)
+                    {
+                        return 0; //Error
+                    }
+                }
+                else if (ap3_set_pin_to_analog(pinNumber) != AP3_OK)
                 {
                     //Serial.println("Error - set pin to analog");
                     return 0; //Error
@@ -335,13 +355,12 @@ ap3_err_t ap3_adc_setup()
 }
 
 //Set function of pin to analog input
-//TODO Support differential pairs 0/1
 ap3_err_t ap3_set_pin_to_analog(uint8_t pinNumber)
 {
     ap3_err_t retval = AP3_ERR;
-
     uint8_t funcsel = 0;
     am_hal_gpio_pincfg_t pincfg = AP3_PINCFG_INPUT;
+
     retval = ap3_analog_pad_funcsel(ap3_gpio_pin2pad(pinNumber), &funcsel);
 
     if (retval != AP3_OK)
@@ -350,10 +369,11 @@ ap3_err_t ap3_set_pin_to_analog(uint8_t pinNumber)
     }
     pincfg.uFuncSel = funcsel; // set the proper function select option for this instance/pin/type combination
     pinMode(pinNumber, pincfg, &retval);
+
     return retval;
 }
 
-//Given pin number, assign ADC function
+//Given pad number, get ADC function
 ap3_err_t ap3_analog_pad_funcsel(ap3_gpio_pad_t padNumber, uint8_t *funcsel)
 {
     ap3_err_t retval = AP3_ERR;

cores/arduino/ard_sup/analog/ap3_analog_structures.c

@@ -28,6 +28,8 @@ const ap3_analog_pad_map_elem_t ap3_analog_map[AP3_ANALOG_PADS] = {
     {.pad = 11, .funcsel = AM_HAL_PIN_11_ADCSE2},
     {.pad = 12, .funcsel = AM_HAL_PIN_12_ADCD0NSE9},
     {.pad = 13, .funcsel = AM_HAL_PIN_13_ADCD0PSE8},
+    {.pad = 14, .funcsel = AM_HAL_PIN_14_ADCD1P},
+    {.pad = 15, .funcsel = AM_HAL_PIN_15_ADCD1N},
     {.pad = 16, .funcsel = AM_HAL_PIN_16_ADCSE0},
     {.pad = 29, .funcsel = AM_HAL_PIN_29_ADCSE1},
     {.pad = 31, .funcsel = AM_HAL_PIN_31_ADCSE3},
@@ -50,8 +52,8 @@ ap3_analog_configure_map_elem_t ap3_analog_configure_map[AP3_ANALOG_CHANNELS] =
     {.pad = 33, .isAnalog = false},
     {.pad = 34, .isAnalog = false},
     {.pad = 35, .isAnalog = false},
-    {.pad = AP3_ADC_DIFF0_PAD, .isAnalog = true},
-    {.pad = AP3_ADC_DIFF1_PAD, .isAnalog = true},
+    {.pad = AP3_ADC_DIFF0_PAD, .isAnalog = false},
+    {.pad = AP3_ADC_DIFF1_PAD, .isAnalog = false},
     {.pad = AP3_ADC_TEMP_PAD, .isAnalog = true},
     {.pad = AP3_ADC_DIV3_PAD, .isAnalog = true},
     {.pad = AP3_ADC_VSS_PAD, .isAnalog = true},

cores/arduino/ard_sup/ap3_analog_types.h

@@ -23,7 +23,7 @@ SOFTWARE.
 #ifndef _AP3_ANALOG_TYPES_H_
 #define _AP3_ANALOG_TYPES_H_
 
-#define AP3_ANALOG_PADS 10
+#define AP3_ANALOG_PADS 12
 #define AP3_ANALOG_CHANNELS 15
 
 enum EXTRA_ADC_PADS

cores/arduino/ard_sup/ap3_gpio.h

@@ -35,25 +35,26 @@ extern const am_hal_gpio_pincfg_t g_AM_HAL_GPIO_OPEN_DRAIN_WITH_READ_12;
 extern const am_hal_gpio_pincfg_t g_AM_HAL_GPIO_INPUT_PULLDOWN;
 
 // macros pointing to internal apollo3 GPIO pincfg structures
-#define AP3_PINCFG_INPUT            (g_AM_HAL_GPIO_INPUT)
-#define AP3_PINCFG_OUTPUT           (g_AM_HAL_GPIO_OUTPUT_WITH_READ_12)
-#define AP3_PINCFG_INPUT_PULLUP     (g_AM_HAL_GPIO_INPUT_PULLUP)
-#define AP3_PINCFG_INPUT_PULLDOWN   (g_AM_HAL_GPIO_INPUT_PULLDOWN)
-#define AP3_PINCFG_OPEN_DRAIN       (g_AM_HAL_GPIO_OPEN_DRAIN_WITH_READ_12)
-#define AP3_PINCFG_TRISTATE         (g_AM_HAL_GPIO_TRISTATE)
+#define AP3_PINCFG_INPUT (g_AM_HAL_GPIO_INPUT)
+#define AP3_PINCFG_OUTPUT (g_AM_HAL_GPIO_OUTPUT_WITH_READ_12)
+#define AP3_PINCFG_INPUT_PULLUP (g_AM_HAL_GPIO_INPUT_PULLUP)
+#define AP3_PINCFG_INPUT_PULLDOWN (g_AM_HAL_GPIO_INPUT_PULLDOWN)
+#define AP3_PINCFG_OPEN_DRAIN (g_AM_HAL_GPIO_OPEN_DRAIN_WITH_READ_12)
+#define AP3_PINCFG_TRISTATE (g_AM_HAL_GPIO_TRISTATE)
 
 // constants for Arduino pin modes
-#define INPUT           (0x00)
-#define OUTPUT          (0x01)
-#define INPUT_PULLUP    (0x02)
-#define INPUT_PULLDOWN  (0x03)
-#define OPEN_DRAIN      (0x04)
-#define TRISTATE        (0x05)
+#define INPUT (0x00)
+#define OUTPUT (0x01)
+#define INPUT_PULLUP (0x02)
+#define INPUT_PULLDOWN (0x03)
+#define OPEN_DRAIN (0x04)
+#define TRISTATE (0x05)
 
 #define AP3_GPIO_MAX_PADS (50)
 #define AP3_GPIO_IS_VALID(pad) ((pad >= 0) && (pad < AP3_GPIO_MAX_PADS))
 
 extern ap3_gpio_pad_t ap3_gpio_pin2pad(ap3_gpio_pin_t pin);
+extern ap3_gpio_pin_t ap3_gpio_pad2pin(ap3_gpio_pad_t pad);
 #define AP3_GPIO_PAD_UNUSED (255)
 
 #define AP3_GPIO_DEFAULT_PINCFG AP3_GPIO_PINCFG_NULL

cores/arduino/ard_sup/gpio/ap3_gpio.cpp

@@ -41,6 +41,16 @@ ap3_gpio_pad_t ap3_gpio_pin2pad(ap3_gpio_pin_t pin)
     return ap3_variant_pinmap[pin];
 }
 
+ap3_gpio_pin_t ap3_gpio_pad2pin(ap3_gpio_pad_t pad)
+{
+    for (int x = 0; x < AP3_VARIANT_NUM_PINS; x++)
+    {
+        if (ap3_variant_pinmap[x] == pad)
+            return (x);
+    }
+    return (AP3_GPIO_PAD_UNUSED);
+}
+
 typedef void (*voidFuncPtr)(void);
 typedef void (*voidFuncPtrArg)(void *);
 typedef struct

libraries/Examples/examples/Advanced/Differential_ADC/Differential_ADC.ino

@@ -0,0 +1,58 @@
+/*
+  Using the differential ADC
+  By: Nathan Seidle
+  SparkFun Electronics
+  Date: July 17th, 2020
+  License: This code is public domain. Based on deepsleep.c from Ambiq SDK v2.2.0.
+
+  There are two differential ADC ports on the Artemis. These are located
+  on pads 12/13 (DIFF0N/DIFF0P) and 14/15 (DIFF1P/DIFF10).
+
+  A differential ADC port measures -1.0V to 1.0V with
+  0 = -1.0V, 8192 = 0V, and 16383 = 1.0V when the ADC is in 14-bit mode.
+
+  Using a trimpot, attach DIFF- to GND and DIFF+ to the center pin of the trimpot.
+  Connect the outer pins of the trimpot to 3.3V and GND.
+  Twisting the trimpot you should see the voltage change from 0 to 1.0V.
+  Switching DIFF-/+ you should see -1.0V to 0V.
+
+  SparkFun labored with love to create this code. Feel like supporting open source hardware?
+  Buy a board from SparkFun! https://www.sparkfun.com/products/15376
+*/
+
+#define ANALOG_RESOLUTION 14 //Artemis has 14 bit ADC but can range from 8 to 14 bit
+
+int maxADCValue = pow(2, ANALOG_RESOLUTION);
+
+void setup()
+{
+    Serial.begin(115200);
+    Serial.println("Differential analog conversion example");
+
+    pinMode(LED_BUILTIN, OUTPUT);
+
+    analogReadResolution(ANALOG_RESOLUTION); //Default is 10 bit. Increase to 14 bit.
+}
+
+void loop()
+{
+    int myAnalog0 = analogRead(ADIFF0); //Pads 12/13. Pins 9/10 on RedBoard Artemis.
+    //int myAnalog0 = analogRead(ADIFF1); //Pads 14/15
+    float myVoltage0 = mapfloat(myAnalog0, 0, maxADCValue, -1.0, 1.0);
+    Serial.print("Diff0 voltage: ");
+    Serial.print(myVoltage0, 3);
+    Serial.println();
+
+    digitalWrite(LED_BUILTIN, HIGH);
+    delay(25);
+    digitalWrite(LED_BUILTIN, LOW);
+    delay(25);
+}
+
+float mapfloat(float x, float in_min, float in_max, float out_min, float out_max)
+{
+    if (x > in_max)
+        x = in_max;
+
+    return (x - in_min) * (out_max - out_min) / (in_max - in_min) + out_min;
+}

variants/artemis_thing_plus/config/variant.cpp

@@ -70,3 +70,4 @@ const ap3_gpio_pin_t ap3_analog_A4 = 23;
 const ap3_gpio_pin_t ap3_analog_A5 = 24;
 const ap3_gpio_pin_t ap3_analog_A6 = 3;
 const ap3_gpio_pin_t ap3_analog_A7 = 9;
+const ap3_gpio_pin_t ap3_analog_DIFF0 = AP3_ADC_DIFF0_PAD;

variants/artemis_thing_plus/config/variant.h

@@ -57,6 +57,7 @@ extern Uart Serial1;
 #define A5 ap3_analog_A5
 #define A6 ap3_analog_A6
 #define A7 ap3_analog_A7
+#define ADIFF0 ap3_analog_DIFF0
 
 // Promise the existence of analog pin names
 extern const ap3_gpio_pin_t ap3_analog_A0;
@@ -67,6 +68,7 @@ extern const ap3_gpio_pin_t ap3_analog_A4;
 extern const ap3_gpio_pin_t ap3_analog_A5;
 extern const ap3_gpio_pin_t ap3_analog_A6;
 extern const ap3_gpio_pin_t ap3_analog_A7;
+extern const ap3_gpio_pin_t ap3_analog_DIFF0;
 
 #define LED_BUILTIN 18
 

variants/redboard_artemis/config/variant.cpp

@@ -76,3 +76,5 @@ const ap3_gpio_pin_t ap3_analog_A6 = 2;
 const ap3_gpio_pin_t ap3_analog_A8 = 8;
 const ap3_gpio_pin_t ap3_analog_A9 = 9;
 const ap3_gpio_pin_t ap3_analog_A10 = 10;
+const ap3_gpio_pin_t ap3_analog_DIFF0 = AP3_ADC_DIFF0_PAD;
+const ap3_gpio_pin_t ap3_analog_DIFF1 = AP3_ADC_DIFF1_PAD;

variants/redboard_artemis/config/variant.h

@@ -72,6 +72,8 @@ extern Uart Serial1;
 #define A8 ap3_analog_A8
 #define A9 ap3_analog_A9
 #define A10 ap3_analog_A10
+#define ADIFF0 ap3_analog_DIFF0
+#define ADIFF1 ap3_analog_DIFF1
 
 // Promise the existence of analog pin names
 extern const ap3_gpio_pin_t ap3_analog_A0;
@@ -85,6 +87,8 @@ extern const ap3_gpio_pin_t ap3_analog_A6;
 extern const ap3_gpio_pin_t ap3_analog_A8;
 extern const ap3_gpio_pin_t ap3_analog_A9;
 extern const ap3_gpio_pin_t ap3_analog_A10;
+extern const ap3_gpio_pin_t ap3_analog_DIFF0;
+extern const ap3_gpio_pin_t ap3_analog_DIFF1;
 
 #define LED_BUILTIN 13