1 files changed, 117 insertions, 0 deletions
diff --git a/src/sensors/dht22.c b/src/sensors/dht22.c
new file mode 100644
index 0000000..9653ba5
--- /dev/null
+++ b/src/sensors/dht22.c
@@ -0,0 +1,117 @@
+#include <sensors/dht22.h>
+
+#ifdef CONFIG_IOE_SENSOR_DHT22
+
+#define PP dht22_ports[pi]
+#define PPP dht22_ports[dht22_measurement.pi]
+
+#define TIMEOUT F_CPU/40000
+
+#define STATUS_NONE 0
+#define STATUS_COMPLETE 1
+#define STATUS_TIMEOUT 2
+
+#define PORT_SENSORW 4
+#define PORT_SENSORRESP_L 3
+#define PORT_SENSORRESP_H 2
+#define PORT_H 1
+#define PORT_L 0
+
+struct {
+    uint8_t index;
+    uint8_t data[5];
+    volatile uint8_t status;
+    uint8_t pi;
+    uint8_t port_status;
+} dht22_measurement;
+
+inline void dht22_init(uint8_t pi) {
+    // Set port as output and set level hight
+    *(PP.DDR) |= PP.MASK;
+    *(PP.PORT) |= PP.MASK;
+    // Enable all pin change interrupts
+    PCIFR = 0xff;
+}
+
+
+inline void dht22_read_deac(uint8_t status) {
+    dht22_measurement.status = status;
+    // Disable pin change interrupt
+    *(PPP.PCMSK) &= ~PPP.PCMSK_MASK;
+    timer_disable(CONFIG_IOE_SENSOR_DHT22_TIMER);
+}
+
+// This is called from pcint.c
+void dht22_read_pcint(void) {
+    switch (dht22_measurement.port_status) {
+    case PORT_L:
+        if (!(*(PPP.PIN) & PPP.MASK))
+            return;
+        dht22_measurement.port_status = PORT_H;
+        break;
+    case PORT_H:
+        if (*(PPP.PIN) & PPP.MASK)
+            return;
+        dht22_measurement.port_status = PORT_L;
+        register uint16_t val;
+        val = timer_value(CONFIG_IOE_SENSOR_DHT22_TIMER);
+        // TODO compare value
+        if (val < 1) {
+            dht22_measurement.data[dht22_measurement.index / 8]
+        }
+        if (++(dht22_measurement.index) == 40) {
+            dht22_read_deac(STATUS_COMPLETE);
+            return;
+        }
+        break;
+    default:
+        if (((*(PPP.PIN) & PPP.MASK) && dht22_measurement.port_status == 3)
+            || !(*(PPP.PIN & PPP.MASK)))
+            return;
+        dht22_measurement.port_status--;
+    }
+    timer_reset(CONFIG_IOE_SENSOR_DHT22_TIMER);
+}
+
+void dht22_read_timer_overflow(void) {
+    dht22_read_deac(STATUS_TIMEOUT);
+}
+
+int8_t dht22_read(uint8_t pi, struct dht22_value *rh,
+                  struct dht22_value *t) {
+    dht22_measurement.index = 0;
+    dht22_measurement.status = STATUS_NONE;
+    dht22_measurement.pi = pi;
+    dht22_measurement.port_status = PORT_SENSORW;
+
+    // Pull port down for 500us
+    *(PP.PORT) &= ~PP.MASK;
+    _delay_us(500);
+    // Initialize timer
+    timer_init(CONFIG_IOE_SENSOR_DHT22_TIMER, TIMER_DIVIDER_64);
+    timer_sethook(CONFIG_IOE_SENSOR_DHT22_TIMER,
+                  dht22_read_timer_overflow);
+    // Set pin change interrupt
+    *(PP.PCMSK) |= PP.PCMSK_MASK;
+    // Set port as output and pull-up resistor
+    *(PP.DDR) &= ~PP.MASK;
+    *(PP.PORT) |= PP.MASK;
+    // Delay till reading is done
+    taskDelayTill(&(dht22_measurement.status));
+
+    // Copy data
+    rh->integral = dht22_measurement.data[0];
+    rh->decimal = dht22_measurement.data[1];
+    t->integral = dht22_measurement.data[2];
+    t->decimal = dht22_measurement.data[3];
+    // Check sum
+    uint8_t sum = dht22_measurement.data[0];
+    sum += dht22_measurement.data[1];
+    sum += dht22_measurement.data[2];
+    sum += dht22_measurement.data[3];
+    if (sum != dht22_measurement.data[4])
+        return 1;
+    return dht22_measurement.status - 1;
+}
+
+#endif /* CONFIG_IOE_SENSOR_SHT22 */