From e69b2bc45ff0940b475a1832d25e051240fbda32 Mon Sep 17 00:00:00 2001
From: Lars-Dominik Braun <lars@6xq.net>
Date: Mon, 10 Mar 2014 17:28:07 +0100
Subject: Initial accel implementation

---
 accel.c | 88 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 88 insertions(+)
 create mode 100644 accel.c

(limited to 'accel.c')

diff --git a/accel.c b/accel.c
new file mode 100644
index 0000000..dc408a3
--- /dev/null
+++ b/accel.c
@@ -0,0 +1,88 @@
+#include <stdio.h>
+#include <string.h>
+#include <avr/io.h>
+#include <avr/interrupt.h>
+#include <avr/sleep.h>
+
+#include "i2c.h"
+#include "accel.h"
+
+/* device address */
+#define LIS302DL 0b00111000
+/* registers */
+#define LIS302DL_WHOAMI 0xf
+#define LIS302DL_CTRLREG1 0x20
+#define LIS302DL_UNUSED1 0x28
+
+#define sleepwhile(cond) \
+	sleep_enable (); \
+	while (cond) { sleep_cpu (); } \
+	sleep_disable ();
+
+/* the first interrupt is lost */
+static volatile bool drdy = true;
+/* 0, 2 and 4 are zero, as they contain the dummy register’s content */
+static volatile int8_t val[6] = {0, 0, 0, 0, 0, 0};
+/* currently reading from i2c */
+static bool reading = false;
+
+#warning "wrong interrupt"
+/* data ready interrupt
+ */
+ISR(PCINT1_vect) {
+	drdy = true;
+}
+
+void accelInit () {
+	/* set PB1 to input, with pull-up */
+	//DDRB = (DDRB & ~((1 << PB1)));
+	//PORTB = (PORTB | (1 << PB1));
+	/* enable interrupt PCI0 */
+	//PCICR = (1 << PCIE0);
+	/* enable interrupts on PB1/PCINT1 */
+	//PCMSK0 = (1 << 1);
+}
+
+/* XXX: make nonblocking */
+void accelStart () {
+	/* configuration:
+	 * disable power-down-mode
+	 * defaults
+	 * data ready interrupt on int2
+	 */
+	uint8_t data[] = {0b01000111, 0b0, 0b00100000};
+
+	if (!twRequest (TWM_WRITE, LIS302DL, LIS302DL_CTRLREG1, data,
+			sizeof (data)/sizeof (*data))) {
+		printf ("cannot start write\n");
+	}
+	sleepwhile (twr.status == TWST_WAIT);
+	printf ("final twi status was %i\n", twr.status);
+}
+
+bool accelProcess () {
+	if (reading) {
+		if (twr.status == TWST_OK) {
+			/* new data transfered */
+			reading = false;
+			return true;
+		} else if (twr.status == TWST_ERR) {
+			printf ("accel i2c error\n");
+			reading = false;
+		}
+	} else {
+		if (drdy && twr.status != TWST_WAIT) {
+			/* new data available in device buffer and bus is free, we are
+			 * reading the registers inbetween out_x/y/z and ignore them */
+			if (!twRequest (TWM_READ, LIS302DL, LIS302DL_UNUSED1, (uint8_t *) val, 6)) {
+				printf ("cannot start read\n");
+			} else {
+				drdy = false;
+				reading = true;
+			}
+		}
+	}
+
+	return false;
+}
+
-- 
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