Import S.Bus driver

drivers/devices/sbus.c

@@ -0,0 +1,51 @@
+#include <stdint.h>
+
+#include <kernel/time.h>
+
+#include "sbus.h"
+
+sbus_t sbus;
+
+static void decode_sbus(uint8_t *frame)
+{
+    sbus.rc_val[0] = ((frame[1] | frame[2] << 8) & 0x07ff);
+    sbus.rc_val[1] = ((frame[2] >> 3 | frame[3] << 5) & 0x07ff);
+    sbus.rc_val[2] =
+        ((frame[3] >> 6 | frame[4] << 2 | frame[5] << 10) & 0x07ff);
+    sbus.rc_val[3] = ((frame[5] >> 1 | frame[6] << 7) & 0x07ff);
+    sbus.rc_val[4] = ((frame[6] >> 4 | frame[7] << 4) & 0x07ff);
+    sbus.rc_val[5] = ((frame[7] >> 7 | frame[8] << 1 | frame[9] << 9) & 0x07ff);
+    sbus.rc_val[6] = ((frame[9] >> 2 | frame[10] << 6) & 0x07ff);
+    sbus.rc_val[7] = ((frame[10] >> 5 | frame[11] << 3) & 0x07ff);
+    sbus.rc_val[8] = ((frame[12] | frame[13] << 8) & 0x07ff);
+    sbus.rc_val[9] = ((frame[13] >> 3 | frame[14] << 5) & 0x07ff);
+    sbus.rc_val[10] =
+        ((frame[14] >> 6 | frame[15] << 2 | frame[16] << 10) & 0x07ff);
+    sbus.rc_val[11] = ((frame[16] >> 1 | frame[17] << 7) & 0x07ff);
+    sbus.rc_val[12] = ((frame[17] >> 4 | frame[18] << 4) & 0x07ff);
+    sbus.rc_val[13] =
+        ((frame[18] >> 7 | frame[19] << 1 | frame[20] << 9) & 0x07ff);
+    sbus.rc_val[14] = ((frame[20] >> 2 | frame[21] << 6) & 0x07ff);
+    sbus.rc_val[15] = ((frame[21] >> 5 | frame[22] << 3) & 0x07ff);
+}
+
+void sbus_interrupt_handler(uint8_t new_byte)
+{
+    sbus.curr_time_ms = ktime_get();
+
+    /* Use reception interval time to deteminate
+       whether it is a new s-bus frame */
+    if ((sbus.curr_time_ms - sbus.last_time_ms) > 2.0f) {
+        sbus.index = 0;
+    }
+
+    sbus.buf[sbus.index] = new_byte;
+    sbus.index++;
+
+    if ((sbus.index == 25) && (sbus.buf[0] == 0x0f) && (sbus.buf[24] == 0x00)) {
+        decode_sbus(sbus.buf);
+        sbus.index = 0;
+    }
+
+    sbus.last_time_ms = sbus.curr_time_ms;
+}

drivers/devices/sbus.h

@@ -0,0 +1,16 @@
+#ifndef __SBUS_H__
+#define __SBUS_H__
+
+#include <stdint.h>
+
+#include <kernel/time.h>
+
+typedef struct {
+    uint8_t buf[25];
+    uint8_t index;
+    uint16_t rc_val[15];
+    ktime_t curr_time_ms;
+    ktime_t last_time_ms;
+} sbus_t;
+
+#endif

drivers/drivers.mk

@@ -7,3 +7,4 @@ SRC += $(PROJ_ROOT)/drivers/periph/uart.c
 SRC += $(PROJ_ROOT)/drivers/periph/pwm.c
 SRC += $(PROJ_ROOT)/drivers/periph/spi.c
 SRC += $(PROJ_ROOT)/drivers/devices/mpu6500.c
+SRC += $(PROJ_ROOT)/drivers/devices/sbus.c