Add trivial ADC support to PX4IO.

apps/px4io/adc.c

@@ -0,0 +1,163 @@
+/****************************************************************************
+ *
+ *   Copyright (C) 2012 PX4 Development Team. All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ * 3. Neither the name PX4 nor the names of its contributors may be
+ *    used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+ * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *
+ ****************************************************************************/
+
+/**
+ * @file adc.c
+ *
+ * Simple ADC support for PX4IO on STM32.
+ */
+#include <nuttx/config.h>
+#include <stdint.h>
+
+#include <nuttx/arch.h>
+#include <arch/stm32/chip.h>
+#include <stm32_internal.h>
+
+#include <drivers/drv_hrt.h>
+#include <systemlib/perf_counter.h>
+
+#define DEBUG
+#include "px4io.h"
+
+/*
+ * Register accessors.
+ * For now, no reason not to just use ADC1.
+ */
+#define REG(_reg)	(*(volatile uint32_t *)(STM32_ADC1_BASE + _reg))
+
+#define rSR		REG(STM32_ADC_SR_OFFSET)
+#define rCR1		REG(STM32_ADC_CR1_OFFSET)
+#define rCR2		REG(STM32_ADC_CR2_OFFSET)
+#define rSMPR1		REG(STM32_ADC_SMPR1_OFFSET)
+#define rSMPR2		REG(STM32_ADC_SMPR2_OFFSET)
+#define rJOFR1		REG(STM32_ADC_JOFR1_OFFSET)
+#define rJOFR2		REG(STM32_ADC_JOFR2_OFFSET)
+#define rJOFR3		REG(STM32_ADC_JOFR3_OFFSET)
+#define rJOFR4		REG(STM32_ADC_JOFR4_OFFSET)
+#define rHTR		REG(STM32_ADC_HTR_OFFSET)
+#define rLTR		REG(STM32_ADC_LTR_OFFSET)
+#define rSQR1		REG(STM32_ADC_SQR1_OFFSET)
+#define rSQR2		REG(STM32_ADC_SQR2_OFFSET)
+#define rSQR3		REG(STM32_ADC_SQR3_OFFSET)
+#define rJSQR		REG(STM32_ADC_JSQR_OFFSET)
+#define rJDR1		REG(STM32_ADC_JDR1_OFFSET)
+#define rJDR2		REG(STM32_ADC_JDR2_OFFSET)
+#define rJDR3		REG(STM32_ADC_JDR3_OFFSET)
+#define rJDR4		REG(STM32_ADC_JDR4_OFFSET)
+#define rDR		REG(STM32_ADC_DR_OFFSET)
+
+perf_counter_t		adc_perf;
+
+int
+adc_init(void)
+{
+	adc_perf = perf_alloc(PC_ELAPSED, "adc");
+
+	/* do calibration if supported */
+#ifdef ADC_CR2_CAL
+	rCR2 |= ADC_CR2_RSTCAL;
+	up_udelay(1);
+	if (rCR2 & ADC_CR2_RSTCAL)
+		return -1;
+	rCR2 |= ADC_CR2_CAL;
+	up_udelay(100);
+	if (rCR2 & ADC_CR2_CAL)
+		return -1;
+#endif
+
+	/* arbitrarily configure all channels for 55 cycle sample time */
+	rSMPR1 = 0b00000011011011011011011011011011;
+	rSMPR2 = 0b00011011011011011011011011011011;
+
+	/* XXX for F2/4, might want to select 12-bit mode? */
+	rCR1 = 0;
+
+	/* enable the temperature sensor / Vrefint channel if supported*/
+	rCR2 = 
+#ifdef ADC_CR2_TSVREFE
+		/* enable the temperature sensor in CR2 */
+		ADC_CR2_TSVREFE |
+#endif
+		0;
+
+#ifdef ADC_CCR_TSVREFE
+	/* enable temperature sensor in CCR */
+	rCCR = ADC_CCR_TSVREFE;
+#endif
+
+	/* configure for a single-channel sequence */
+	rSQR1 = 0;
+	rSQR2 = 0;
+	rSQR3 = 0;	/* will be updated with the channel each tick */ 
+
+	/* power-cycle the ADC and turn it on */
+	rCR2 &= ~ADC_CR2_ADON;
+	up_udelay(10);
+	rCR2 |= ADC_CR2_ADON;
+	up_udelay(10);
+	rCR2 |= ADC_CR2_ADON;
+	up_udelay(10);
+
+	return 0;
+}
+
+uint16_t
+adc_measure(unsigned channel)
+{
+	perf_begin(adc_perf);
+
+	/* clear any previous EOC */
+	if (rSR & ADC_SR_EOC)
+		rSR &= ~ADC_SR_EOC;
+
+	/* run a single conversion right now - should take about 60 cycles (a few microseconds) max */
+	rSQR3 = channel;
+	rCR2 |= ADC_CR2_ADON;
+
+	/* wait for the conversion to complete */
+	hrt_abstime now = hrt_absolute_time();
+	while (!(rSR & ADC_SR_EOC)) {
+
+		/* never spin forever - this will give a bogus result though */
+		if ((hrt_absolute_time() - now) > 1000) {
+			debug("adc timeout");
+			break;
+		}
+	}
+
+	/* read the result and clear EOC */
+	uint16_t result = rDR;
+
+	perf_end(adc_perf);
+	return result;	
+}	

apps/px4io/px4io.h

@@ -160,6 +160,12 @@ extern void	safety_init(void);
  */
 extern void	comms_main(void) __attribute__((noreturn));
 
+/*
+ * Sensors/misc inputs
+ */
+extern int	adc_init(void);
+extern uint16_t	adc_measure(unsigned channel);
+
 /*
  * R/C receiver handling.
  */