samples: add a sample app using TI INA219 power monitor

This is a sample app to interface with TI INA219 power monitor.
The values used in the app are for use on Adafruit's breakout board
(https://www.adafruit.com/products/904).

This assumes the slave address is 0x40, where A0 and A1 are all
tied to ground.

Change-Id: I4116629171a98be6f2b9aa422dd3eb386b4d59c2
Signed-off-by: Daniel Leung <daniel.leung@intel.com>
Signed-off-by: Anas Nashif <anas.nashif@intel.com>

samples/nanokernel/apps/current_sensing/Makefile

@@ -0,0 +1,5 @@
+BOARD ?= arduino_101_sss
+KERNEL_TYPE = nano
+CONF_FILE = prj.conf
+
+include ${ZEPHYR_BASE}/Makefile.inc

samples/nanokernel/apps/current_sensing/README

@@ -0,0 +1,8 @@
+This is a sample app to interface with
+TI INA219 power monitor. The values
+used in the app are for use on Adafruit's
+breakout board
+(https://www.adafruit.com/products/904).
+
+This assumes the slave address is 0x40,
+where A0 and A1 are all tied to ground.

samples/nanokernel/apps/current_sensing/prj.conf

@@ -0,0 +1,4 @@
+CONFIG_STDOUT_CONSOLE=y
+CONFIG_PRINTK=y
+
+CONFIG_I2C=y

samples/nanokernel/apps/current_sensing/src/Makefile

@@ -0,0 +1 @@
+obj-y = main.o

samples/nanokernel/apps/current_sensing/src/main.c

@@ -0,0 +1,138 @@
+/*
+ * Copyright (c) 2016 Intel Corporation
+ *
+ * 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 <zephyr.h>
+
+#include <misc/printk.h>
+
+#include <device.h>
+#include <i2c.h>
+
+/**
+ * @file Sample app using the TI INA219 through I2C.
+ */
+
+#define I2C_SLV_ADDR	0x40
+
+/* The calibration value is based on components on
+ * Adafruit's breakout board
+ * (https://www.adafruit.com/products/904), where
+ * the current sensing resistor is 0.1 ohm.
+ * This enables measurements up to 32V, 2A.
+ */
+#define CAL_VAL		(4096)
+
+/* With default calibration above,
+ * Each current LSB is 100 uA == 0.1 mA == 0.0001 A.
+ * Each power LSB is 2000 uW == 2 mW = 0.002W.
+ */
+#define CUR_LSB		100
+#define PWR_LSB		2000
+
+int read_reg16(struct device *i2c_dev, uint8_t reg_addr,
+	       uint8_t *data)
+{
+	uint8_t wr_addr;
+	struct i2c_msg msgs[2];
+
+	/* Register address */
+	wr_addr = reg_addr;
+
+	/* Setup I2C messages */
+
+	/* Send the address to read */
+	msgs[0].buf = &wr_addr;
+	msgs[0].len = 1;
+	msgs[0].flags = I2C_MSG_WRITE;
+
+	/* Read from device. RESTART as neededm and STOP after this. */
+	msgs[1].buf = data;
+	msgs[1].len = 2;
+	msgs[1].flags = I2C_MSG_READ | I2C_MSG_RESTART | I2C_MSG_STOP;
+
+	return i2c_transfer(i2c_dev, &msgs[0], 2, I2C_SLV_ADDR);
+}
+
+int write_reg16(struct device *i2c_dev, uint8_t reg_addr,
+		uint8_t *data)
+{
+	uint8_t wr_addr;
+	struct i2c_msg msgs[2];
+
+	/* Register address */
+	wr_addr = reg_addr;
+
+	/* Setup I2C messages */
+
+	/* Send the address to read */
+	msgs[0].buf = &wr_addr;
+	msgs[0].len = 1;
+	msgs[0].flags = I2C_MSG_WRITE;
+
+	/* Read from device. RESTART as neededm and STOP after this. */
+	msgs[1].buf = data;
+	msgs[1].len = 2;
+	msgs[1].flags = I2C_MSG_WRITE | I2C_MSG_STOP;
+
+	return i2c_transfer(i2c_dev, &msgs[0], 2, I2C_SLV_ADDR);
+}
+
+void main(void)
+{
+	struct device *i2c_dev;
+	uint8_t data[2];
+	uint32_t shunt_volt, bus_volt, current, power;
+
+	i2c_dev = device_get_binding("I2C0");
+	if (!i2c_dev) {
+		printk("I2C: Device not found.\n");
+	}
+
+	/* Configurate the chip using default values */
+	data[0] = 0x03;
+	data[1] = 0x99;
+	write_reg16(i2c_dev, 0x00, data);
+
+	/* Write the calibration value */
+	data[0] = (CAL_VAL & 0xFF00) >> 8;
+	data[1] = CAL_VAL & 0xFF;
+	write_reg16(i2c_dev, 0x05, data);
+
+	/* Read bus voltage */
+	read_reg16(i2c_dev, 0x02, data);
+	bus_volt = (data[0] << 8) | data[1];
+	bus_volt >>= 3; /* 3 LSBs are not data */
+	bus_volt *= 4; /* each LSB is 4 mV */
+	printk("Bus Voltage: %d mV\n", bus_volt);
+
+	/* Read shunt voltage */
+	read_reg16(i2c_dev, 0x01, data);
+	shunt_volt = (data[0] << 8) | data[1];
+	shunt_volt *= 10; /* to uV since each LSB is 0.01 mV */
+	printk("Shunt Voltage: %d uV\n", shunt_volt);
+
+	/* Read current */
+	read_reg16(i2c_dev, 0x04, data);
+	current = (data[0] << 8) | data[1];
+	current *= CUR_LSB;
+	printk("Current: %d uA\n", current);
+
+	/* Read power  */
+	read_reg16(i2c_dev, 0x03, data);
+	power = (data[0] << 8) | data[1];
+	power *= PWR_LSB;
+	printk("Power: %d uW\n", power);
+}

samples/nanokernel/apps/current_sensing/testcase.ini

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+[test]
+build_only = true
+tags = board_arduino_101
+
+arch_whitelist = arc x86
+platform_whitelist = arduino_101_sss quark_d2000_crb