Add initial code for supporting a better temperature sensor (AM2302)

Author: kenchris

zephyr/x86_app/prj.conf

@@ -13,6 +13,7 @@ CONFIG_PWM=y
 CONFIG_PWM_QMSI_NUM_PORTS=3
 CONFIG_PWM_DW=n
 CONFIG_PWM_QMSI=y
+CONFIG_GPIO=y
 CONFIG_ARC_INIT=y
 CONFIG_IPM=y
 CONFIG_IPM_QUARK_SE=y

zephyr/x86_app/src/service.c

@@ -38,6 +38,9 @@
 #include <bluetooth/uuid.h>
 #include <bluetooth/gatt.h>
 
+#include <gpio.h>
+#include <sys_clock.h>
+
 QUARK_SE_IPM_DEFINE(temperature_ipm, 0, QUARK_SE_IPM_INBOUND);
 
 #define BT_UUID_WEBBT BT_UUID_DECLARE_16(0xfc00)
@@ -53,7 +56,7 @@ static uint8_t simulate_blvl;
 static uint8_t temperature = 20;
 static uint8_t rgb[3] = {0xff, 0x00, 0x00}; // red
 
-struct device *pwm, *tmp36;
+struct device *pwm, *tmp36, *tmp2302;
 #define IO3_RED   0
 #define IO5_GREEN 1
 #define IO6_BLUE  2
@@ -65,6 +68,22 @@ struct device *pwm, *tmp36;
 #define PERIOD 64000
 #define MAX(a,b) (((a)>(b))?(a):(b))
 
+#if defined(CONFIG_GPIO_DW_0)
+#define GPIO_DRV_NAME CONFIG_GPIO_DW_0_NAME
+#elif defined(CONFIG_GPIO_QMSI_0)
+#define GPIO_DRV_NAME CONFIG_GPIO_QMSI_0_NAME
+#elif defined(CONFIG_GPIO_ATMEL_SAM3)
+#define GPIO_DRV_NAME CONFIG_GPIO_ATMEL_SAM3_PORTB_DEV_NAME
+#elif
+#define GPIO_DRV_NAME "GPIO_0"
+#endif
+
+#define IO8_AM2302 16
+
+uint32_t start_time;
+uint32_t stop_time;
+uint32_t cycles_spent;
+
 void pwm_write(void)
 {
     uint32_t r_on, g_on, b_on;
@@ -160,9 +179,145 @@ void temperature_ipm_callback(void *context, uint32_t id, volatile void *data)
     bt_gatt_notify(conn, &attrs[2], &temperature, sizeof(temperature));
 }
 
+uint32_t measure_signal(uint32_t signal)
+{
+    uint32_t count = 1;
+
+    uint32_t readValue;
+
+    start_time = sys_cycle_get_32();
+
+    do {
+      gpio_pin_read(tmp2302, IO8_AM2302, &readValue);
+      if (count++ > 255) return -1;
+    } while (readValue == signal);
+
+    stop_time = sys_cycle_get_32();
+
+    cycles_spent = stop_time - start_time;
+    return SYS_CLOCK_HW_CYCLES_TO_NS(cycles_spent) / 1000; // Microseconds
+}
+
+int verifyResponse(uint32_t response)
+{
+    if (response >= 75 && response <= 85)
+        return 1;
+    return -1;
+}
+
+int verifyLowSignal(uint32_t low)
+{
+    if (low >= 48 && low <= 55)
+        return 1;
+    return -1;
+}
+
+int checkHighSignal(uint32_t high)
+{
+    if (high >= 68 && high <= 75)
+        return 1;
+    if (high >= 22 && high <= 30)
+        return 0;
+    return -1;
+}
+
+void read_am2302_tmp()
+{
+    uint32_t cycles[80];
+
+    gpio_pin_configure(tmp2302, IO8_AM2302, (GPIO_DIR_OUT));
+    gpio_pin_write(tmp2302, IO8_AM2302, 1);
+    task_sleep(USEC(1000));
+
+   // STEP 1+2
+
+   // We set MCU to output.
+   // Due to previous pullup, it should always be high.
+
+   // We signal the AM2302 to wake up, by signaling
+   // low for min 800us, but typically 1ms. (max 20ms).
+   gpio_pin_write(tmp2302, IO8_AM2302, 0);
+   task_sleep(USEC(1000));
+
+   // End the start signal by setting data line high for 40 microseconds.
+   gpio_pin_write(tmp2302, IO8_AM2302, 1);
+   task_sleep(USEC(40));
+
+   // Then set MCU to input and release the bus
+   // Due to pullup, it will go high and it will take
+   // at least 20us, though typically 30ns and
+   // max 200ns for the AM2302 to signal low.
+   gpio_pin_configure(tmp2302, IO8_AM2302, (GPIO_DIR_IN));
+   task_sleep(USEC(10));
+
+   // Signal from AM2302 that it is ready to send data.
+
+   uint32_t time;
+
+   time = measure_signal(0);
+   if (verifyResponse(time) < 0)
+       printk("Response low time not within limits: %d\n", time);
+   time = measure_signal(1);
+   if (verifyResponse(time) < 0)
+       printk("Response high time not within limits: %d\n", time);
+
+   // Read data.
+   for (int i = 0; i < 80; i += 2) {
+       cycles[i] = measure_signal(0);
+       cycles[i+1] = measure_signal(1);
+   }
+
+   // -- Timing critical code is now over. --
+
+   uint8_t dataset[5];
+
+   // Each data set is 5 bytes (5 * 8 = 40)
+   for (int i = 0; i < 40; ++i) {
+       uint32_t low = cycles[2*i];
+       uint32_t high = cycles[2*i+1];
+
+       dataset[i/8] <<= 1; // Move existing value one bit.
+
+       int lowstate = verifyLowSignal(low);
+       int highstate = checkHighSignal(high);
+
+       if (highstate == 1)
+           dataset[i/8] |= 1;
+
+       if (lowstate < 0 || highstate < 0) printk("X: "); else printk("%d: ", highstate);
+       printk("low"); if (lowstate < 0) printk("*"); printk("\t: %d\t/\t", low);
+       printk("high"); if (highstate < 0) printk("*"); printk("\t: %d\n", high);
+       if ((i + 1) % 8 == 0) printk("\n");
+    }
+
+    // Debugging:
+    for (int j = 0; j < 5; j++){
+        printk("%d ", dataset[j]);
+    }
+    printk("\n");
+
+    // Checksum check:
+    if (dataset[4] != ((dataset[0] + dataset[1] + dataset[2] + dataset[3]) & 0xFF)) {
+        printk("Checksum failed!\n");
+    }
+
+    float humidity = (float) (dataset[0] << 8 | dataset[1]) / 10.0;
+    printk("Humidity: %f \n", humidity);
+    float temperature;
+
+    int neg = dataset[2] & 0x80; // higtest bit only.
+    dataset[2] &= 0x7F; // Remove highest bit.
+
+    temperature = (float) (dataset[2] << 8 | dataset[3]) / 10.0;
+    if (neg > 0)
+        temperature *= -1;
+
+    printk("Temperature: %f \n", temperature);
+}
+
 void service_init(struct bt_conn *conn)
 {
-    if ((pwm = device_get_binding("PWM")) == NULL)
+    if ((pwm = device_get_binding("PWM_0")) == NULL)
         printk("device_get_binding: failed for PWM\n");
     else {
         pwm_write();
@@ -176,4 +331,10 @@ void service_init(struct bt_conn *conn)
     ipm_set_enabled(ipm, 1);
 
     bt_gatt_register(attrs, ARRAY_SIZE(attrs));
+
+    if((tmp2302 = device_get_binding(GPIO_DRV_NAME)) == NULL)
+        printk("device_get_binding: failed for TMP2302\n");
+    else {
+        read_am2302_tmp();
+    }
 }