Diff: targets/hal/TARGET_ARM_SSG/TARGET_BEETLE/analogin_api.c

Revision:

144:ef7eb2e8f9f7

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/targets/hal/TARGET_ARM_SSG/TARGET_BEETLE/analogin_api.c	Fri Sep 02 15:07:44 2016 +0100
@@ -0,0 +1,148 @@
+/*
+ * PackageLicenseDeclared: Apache-2.0
+ * Copyright (c) 2016 ARM Limited
+ *
+ * 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 "cmsis.h"
+#include "mbed_assert.h"
+#include "wait_api.h"
+#include "analogin_api.h"
+#include "gpio_api.h"
+#include "spi_api.h"
+#include "pinmap.h"
+
+#if DEVICE_ANALOGIN
+
+/*
+ * Channel Address for the next acquisition:
+ * XXAAAXXX XXXXXXXX
+ */
+#define ADC_SPI_ADDRESS  11
+
+/* ADC Resolution */
+#define ADC_RESOLUTION  0xFFF
+
+/* ADC Voltage Divider */
+#define ADC_DIV   819.0
+
+/* PinMap structure for ADC IN */
+static const PinMap PinMap_ADC[] = {
+    {A0, ADC0_0, 0},
+    {A1, ADC0_1, 0},
+    {A2, ADC0_2, 0},
+    {A3, ADC0_3, 0},
+    {A4, ADC0_4, 0},
+    {A5, ADC0_5, 0},
+    {NC, NC, 0}
+};
+
+/* ADC SPI Private Data */
+typedef struct {
+    /* ADC SPI */
+    spi_t analogin_spi;
+    /* ADC SPI CS */
+    gpio_t adc_spi_cs_gpio;
+    /* ADC SPI State */
+    uint32_t analog_spi_inited;
+} analogin_spi_t;
+/* ADC SPI Device */
+static analogin_spi_t analogin_spi_dev;
+
+/*
+ * ADC SPI CS
+ */
+#define ADC_SPI_CS  P1_2
+
+/*
+ * Initialize the analogin peripheral
+ * Configures the pin used by analogin.
+ * obj: The analogin object to initialize
+ * pin: The analogin pin name
+ */
+void analogin_init(analogin_t *obj, PinName pin)
+{
+    /* Initialize ADC Pin */
+    obj->adc = (ADCName)pinmap_peripheral(pin, PinMap_ADC);
+    /* Verify if pin is valid */
+    MBED_ASSERT(obj->adc != (ADCName)NC);
+
+    /* Initialize the ADC SPI */
+    if(analogin_spi_dev.analog_spi_inited == 0){
+        /* Initialize SPI for ADC */
+        spi_init(&(analogin_spi_dev.analogin_spi), ADC_SPI_MOSI,
+                ADC_SPI_MISO, ADC_SPI_SCK, ADC_SPI_nCS);
+        spi_format(&(analogin_spi_dev.analogin_spi), 16, 3, 0);
+        /* Set SPI to MAX Freq */
+        spi_frequency(&(analogin_spi_dev.analogin_spi), 0);
+
+        /* Initialize CS GPIO */
+        gpio_init_out(&(analogin_spi_dev.adc_spi_cs_gpio), ADC_SPI_CS);
+
+        analogin_spi_dev.analog_spi_inited = 1;
+    }
+
+    /* If pin is valid assign it to the ADC data structure */
+    obj->pin = pin;
+    obj->pin_number = pin-600;
+    obj->address = (0x0000 | (pin-600));
+
+    /* Configure the pinout */
+    pinmap_pinout(pin, PinMap_ADC);
+}
+
+/*
+ * Read the value from analogin pin, represented as an unsigned 16bit value
+ * obj: The analogin object
+ * @return: An unsigned 16bit value representing the current input voltage
+ */
+uint16_t analogin_read_u16(analogin_t *obj)
+{
+    uint16_t result = 0;
+
+    /*
+     * The ADC SPI hw is 8 bit format, 16 bit emulation is required
+     * in the SPI driver.
+     */
+    /* CS = 1 */
+    gpio_write(&(analogin_spi_dev.adc_spi_cs_gpio), 1);
+    /* Do the first read */
+    (void)spi_master_write(&(analogin_spi_dev.analogin_spi),
+        ((obj->pin_number) << ADC_SPI_ADDRESS));
+    /* CS = 0 */
+    gpio_write(&(analogin_spi_dev.adc_spi_cs_gpio), 0);
+    /* Wait 50 us */
+    wait_us(50);
+    /* CS = 1 */
+    gpio_write(&(analogin_spi_dev.adc_spi_cs_gpio), 1);
+    /* The second read provides the result */
+    result = spi_master_write(&(analogin_spi_dev.analogin_spi),
+        ((obj->pin_number) << ADC_SPI_ADDRESS));
+    /* CS = 0 */
+    gpio_write(&(analogin_spi_dev.adc_spi_cs_gpio), 0);
+
+    return result;
+}
+
+/*
+ * Read the input voltage, represented as a float in the range [0.0, 1.0]
+ * obj: The analogin object
+ * @return: A floating value representing the current input voltage
+ */
+float analogin_read(analogin_t *obj)
+{
+    uint16_t result = analogin_read_u16(obj);
+    return (float)((result & ADC_RESOLUTION) * 1.0f) / ADC_DIV;
+}
+
+#endif