Diff: targets/TARGET_Silicon_Labs/TARGET_EFM32/analogout_api.c

Revision:

149:156823d33999

Parent:

144:ef7eb2e8f9f7

Child:

150:02e0a0aed4ec

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/targets/TARGET_Silicon_Labs/TARGET_EFM32/analogout_api.c	Fri Oct 28 11:17:30 2016 +0100
@@ -0,0 +1,143 @@
+/***************************************************************************//**
+ * @file analogout_aoi.c
+ *******************************************************************************
+ * @section License
+ * <b>(C) Copyright 2015 Silicon Labs, http://www.silabs.com</b>
+ *******************************************************************************
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License"); you may
+ * not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ ******************************************************************************/
+
+#include "device.h"
+#if DEVICE_ANALOGOUT
+
+#include "mbed_assert.h"
+#include "error.h"
+#include "analogout_api.h"
+#include "pinmap.h"
+#include "pinmap_function.h"
+#include "PeripheralPins.h"
+#include "clocking.h"
+
+#include "em_dac.h"
+#include "em_cmu.h"
+
+static uint8_t dac_initialized = 0;
+
+void analogout_init(dac_t *obj, PinName pin)
+{
+    /* init in-memory structure */
+    obj->dac = (DAC_TypeDef *) pinmap_peripheral(pin, PinMap_DAC);
+    MBED_ASSERT((int) obj->dac != NC);
+
+    obj->channel = pin_location(pin, PinMap_DAC);
+    MBED_ASSERT((int) obj->channel != NC);
+    
+    pin_mode(pin, Disabled);
+
+    if (!dac_initialized) {
+        /* Initialize the DAC. Will disable both DAC channels, so should only be done once */
+        /* Use default settings */
+        CMU_ClockEnable(cmuClock_DAC0, true);
+
+        DAC_Init_TypeDef init = DAC_INIT_DEFAULT;
+
+        /* Calculate the DAC clock prescaler value that will result in a DAC clock
+         * close to 500kHz. Second parameter is zero. This uses the current HFPERCLK
+         * frequency instead of setting a new one. */
+        init.prescale = DAC_PrescaleCalc(500000, REFERENCE_FREQUENCY);
+
+        /* Set reference voltage to VDD */
+        init.reference = dacRefVDD;
+
+        DAC_Init(obj->dac, &init);
+        dac_initialized = 1;
+    }
+    /* Use default channel settings */
+    DAC_InitChannel_TypeDef initChannel = DAC_INITCHANNEL_DEFAULT;
+    initChannel.enable = true;
+    DAC_InitChannel(obj->dac, &initChannel, obj->channel);
+}
+
+void analogout_free(dac_t *obj)
+{
+    //Reset channel by re-initializing
+    DAC_InitChannel_TypeDef initChannel = DAC_INITCHANNEL_DEFAULT;
+    initChannel.enable = false;
+    DAC_InitChannel(obj->dac, &initChannel, obj->channel);
+    
+    //Check all channels to see if we can disable the DAC completely
+    if((DAC0->CH0CTRL & DAC_CH0CTRL_EN) == 0 && (DAC0->CH1CTRL & DAC_CH1CTRL_EN) == 0) {
+        CMU_ClockEnable(cmuClock_DAC0, false);
+        dac_initialized = 0;
+    }
+}
+
+static inline void dac_write(dac_t *obj, int value)
+{
+    switch (obj->channel) {
+        case 0:
+            obj->dac->CH0DATA = value;
+            break;
+        case 1:
+            obj->dac->CH1DATA = value;
+            break;
+    }
+}
+
+static inline int dac_read(dac_t *obj)
+{
+    switch (obj->channel) {
+        case 0:
+            return obj->dac->CH0DATA;
+            break;
+        case 1:
+            return obj->dac->CH1DATA;
+            break;
+        default:
+            error("AnalogOut pin error. Invalid channel");
+            return -1;
+            break;
+    }
+}
+
+void analogout_write(dac_t *obj, float value)
+{
+    /* We multiply the float value with 0xFFF because the DAC has 12-bit resolution.
+     * Ie. accepts values between 0 and 0xFFF (4096). */
+    dac_write(obj, value*0xFFF);
+}
+
+void analogout_write_u16(dac_t *obj, uint16_t value)
+{
+    /* The DAC has 12 bit resolution, so we remove the 4 least significant bits */
+    dac_write(obj, value >> 4);
+}
+
+float analogout_read(dac_t *obj)
+{
+    /* dac_read returns a number between 0 and 0xFFF. Division gives us a float between 0 and 1 */
+    return dac_read(obj)/(float)0xFFF;
+}
+
+uint16_t analogout_read_u16(dac_t *obj)
+{
+    /* dac_read returns a number with 12 significant digits,
+     * so we shift in 0s from right to make it a 16 bit number */
+    return dac_read(obj) << 4;
+}
+
+#endif