Initial Release

main/component.mk

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+#
+# Main Makefile. This is basically the same as a component makefile.
+#

main/dac-cosine.c

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+/* DAC Cosine Generator Example
+
+   This example code is in the Public Domain (or CC0 licensed, at your option.)
+
+   Unless required by applicable law or agreed to in writing, this
+   software is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR
+   CONDITIONS OF ANY KIND, either express or implied.
+*/
+#include <stdio.h>
+#include <string.h>
+#include <stdlib.h>
+#include "freertos/FreeRTOS.h"
+#include "freertos/task.h"
+#include "freertos/queue.h"
+
+#include "soc/rtc_io_reg.h"
+#include "soc/rtc_cntl_reg.h"
+#include "soc/sens_reg.h"
+
+#include "driver/dac.h"
+
+/* Declare global sine waveform parameters
+ * so they may be then accessed and changed from debugger
+ * over an JTAG interface
+ */
+int frequency = 8;    // about 1kHz
+int scale = 1;        // 50% of the full scale
+int offset;           // leave it default / 0 = no any offset
+int invert = 2;       // invert MSB to get sine waveform
+
+
+/*
+ * Enable cosine waveform generator on a DAC channel
+ */
+void dac_cosine_enable(dac_channel_t channel)
+{
+    // Enable tone generator common to both channels
+    SET_PERI_REG_MASK(SENS_SAR_DAC_CTRL1_REG, SENS_SW_TONE_EN);
+    switch(channel) {
+        case DAC_CHANNEL_1:
+            // Enable / connect tone tone generator on / to this channel
+            SET_PERI_REG_MASK(SENS_SAR_DAC_CTRL2_REG, SENS_DAC_CW_EN1_M);
+            // Invert MSB, otherwise part of waveform will have inverted
+            SET_PERI_REG_BITS(SENS_SAR_DAC_CTRL2_REG, SENS_DAC_INV1, 2, SENS_DAC_INV1_S);
+            break;
+        case DAC_CHANNEL_2:
+            SET_PERI_REG_MASK(SENS_SAR_DAC_CTRL2_REG, SENS_DAC_CW_EN2_M);
+            SET_PERI_REG_BITS(SENS_SAR_DAC_CTRL2_REG, SENS_DAC_INV2, 2, SENS_DAC_INV2_S);
+            break;
+        default :
+           printf("Channel %d\n", channel);
+    }
+}
+
+
+/*
+ * Set frequency of internal CW generator common to both DAC channels
+ *
+ * Range 0x0001 - 0xFFFF
+ *
+ */
+void dac_frequency_set(int frequency)
+{
+    SET_PERI_REG_BITS(SENS_SAR_DAC_CTRL1_REG, SENS_SW_FSTEP, frequency, SENS_SW_FSTEP_S);
+}
+
+
+/*
+ * Scale output of a DAC channel using two bit pattern:
+ *
+ * - 00: no scale
+ * - 01: scale to 1/2
+ * - 10: scale to 1/4
+ * - 11: scale to 1/8
+ *
+ */
+void dac_scale_set(dac_channel_t channel, int scale)
+{
+    switch(channel) {
+        case DAC_CHANNEL_1:
+            SET_PERI_REG_BITS(SENS_SAR_DAC_CTRL2_REG, SENS_DAC_SCALE1, scale, SENS_DAC_SCALE1_S);
+            break;
+        case DAC_CHANNEL_2:
+            SET_PERI_REG_BITS(SENS_SAR_DAC_CTRL2_REG, SENS_DAC_SCALE2, scale, SENS_DAC_SCALE2_S);
+            break;
+        default :
+           printf("Channel %d\n", channel);
+    }
+}
+
+
+/*
+ * Offset output of a DAC channel
+ *
+ * Range 0x00 - 0xFF
+ *
+ */
+void dac_offset_set(dac_channel_t channel, int offset)
+{
+    switch(channel) {
+        case DAC_CHANNEL_1:
+            SET_PERI_REG_BITS(SENS_SAR_DAC_CTRL2_REG, SENS_DAC_DC1, offset, SENS_DAC_DC1_S);
+            break;
+        case DAC_CHANNEL_2:
+            SET_PERI_REG_BITS(SENS_SAR_DAC_CTRL2_REG, SENS_DAC_DC2, offset, SENS_DAC_DC2_S);
+            break;
+        default :
+           printf("Channel %d\n", channel);
+    }
+}
+
+
+/*
+ * Invert output pattern of a DAC channel
+ *
+ * - 00: does not invert any bits,
+ * - 01: inverts all bits,
+ * - 10: inverts MSB,
+ * - 11: inverts all bits except for MSB
+ *
+ */
+void dac_invert_set(dac_channel_t channel, int invert)
+{
+    switch(channel) {
+        case DAC_CHANNEL_1:
+            SET_PERI_REG_BITS(SENS_SAR_DAC_CTRL2_REG, SENS_DAC_INV1, invert, SENS_DAC_INV1_S);
+            break;
+        case DAC_CHANNEL_2:
+            SET_PERI_REG_BITS(SENS_SAR_DAC_CTRL2_REG, SENS_DAC_INV2, invert, SENS_DAC_INV2_S);
+            break;
+        default :
+           printf("Channel %d\n", channel);
+    }
+}
+
+
+void dactask(void* arg)
+{
+    while(1){
+
+        // frequency setting is common to both channels
+        dac_frequency_set(frequency);
+
+        /* Tune parameters of channel 2 only
+         * to see and compare changes against channel 1
+         */
+        dac_scale_set(DAC_CHANNEL_2, scale);
+        dac_offset_set(DAC_CHANNEL_2, offset);
+        dac_invert_set(DAC_CHANNEL_2, invert);
+
+        printf("DAC frequency: %5d, DAC2 scale: %d, offset %3d, invert: %d\n", frequency, scale, offset, invert);
+        vTaskDelay(1000/portTICK_PERIOD_MS);
+    }
+}
+
+/*
+ * Generate a sine waveform on both DAC channels:
+ *
+ * DAC_CHANNEL_1 - GPIO25
+ * DAC_CHANNEL_2 - GPIO26
+ *
+ * Connect scope to both GPIO25 and GPIO26
+ * to observe the waveform changes
+ * in response to the parameter change
+*/
+void app_main()
+{
+    dac_cosine_enable(DAC_CHANNEL_1);
+    dac_cosine_enable(DAC_CHANNEL_2);
+
+    dac_output_enable(DAC_CHANNEL_1);
+    dac_output_enable(DAC_CHANNEL_2);
+
+    xTaskCreate(dactask, "dactask", 1024*3, NULL, 10, NULL);
+}