1 files changed, 90 insertions, 0 deletions
diff --git a/libmaple/adc.c b/libmaple/adc.c
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+++ b/libmaple/adc.c
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+/* *****************************************************************************
+ *  This program is free software: you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation, either version 3 of the License, or
+ *  (at your option) any later version.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ *  Created: 12/18/09 02:34:47
+ *  Copyright (c) 2009 Perry L. Hung. All rights reserved.
+ *
+ * ****************************************************************************/
+
+/**
+ *  @file adc.c
+ *
+ *  @brief Analog to digital converter routines
+ */
+
+#include "libmaple.h"
+#include "rcc.h"
+#include "adc.h"
+
+/* The ADC input clock is generated from PCLK2/APB2 divided by a prescaler
+ * and it must not exceed 14MHz.
+ *
+ * ADC1 and ADC2 are clocked by APB2
+ *
+ * 1) Power on by setting ADON in ADC_CR2
+ * Conversion starts when ADON is set for a second time after some
+ * time t > t_stab.
+ *
+ * Up to 16 selected conversion must be selected in ADC_SQRx
+ *
+ * Single conversion mode:
+ * Set the ADON bit in the ADC_CR2 register
+ * Once the conversion is complete:
+ *  Converted data is stored in ADC_DR
+ *  EOC flag is set
+ *  Interrupt is generated if EOCIE is set
+ *
+ * Calibration:
+ * Calibration is started by setting the CAL bit in the ADC_CR2 register.
+ * Once calibration is over, the CAL bit is reset by hardware and normal
+ * conversion can be performed. Calibrate at power-on.
+ *
+ * ALIGN in ADC_CR2 selects the alignment of data
+ *
+ * IMPORTANT: maximum external impedance must be below 0.4kOhms for 1.5
+ * sample conversion time.
+ *
+ * At 55.5 cycles/sample, the external input impedance < 50kOhms*/
+
+void adc_init(void) {
+   rcc_set_adc_prescaler(PCLK2_DIV_2);
+   rcc_enable_clk_adc1();
+   rcc_reset_adc1();
+
+    ADC_CR1  = 0;
+    ADC_CR2  = CR2_EXTSEL_SWSTART | CR2_EXTTRIG;  // Software triggers conversions
+    ADC_SQR1 = 0;
+
+    /* Up the sample conversion time to 55.5 cycles/sec, see note above  */
+    /* TODO: fix magic numbers  */
+    ADC_SMPR1 = 0xB6DB6D;
+    ADC_SMPR2 = 0x2DB6DB6D;
+
+    /* Enable the ADC  */
+    CR2_ADON_BIT = 1;
+
+    /* Reset the calibration registers and then perform a reset  */
+    CR2_RSTCAL_BIT = 1;
+    while(CR2_RSTCAL_BIT)
+        ;
+
+    CR2_CAL_BIT = 1;
+    while(CR2_CAL_BIT)
+        ;
+}
+
+
+void adc_disable(void) {
+    CR2_ADON_BIT = 0;
+}