From 02d31522cde1de13ab397f4fbd77c0cf9b7f712d Mon Sep 17 00:00:00 2001
From: Daniel Shiels <diyd5@tofubar.com>
Date: Wed, 29 Oct 2014 22:00:30 +1100
Subject: First attempt at sbus1 output.

---
 src/modules/px4iofirmware/sbus.c | 37 ++++++++++++++++++++++++++++++++++---
 1 file changed, 34 insertions(+), 3 deletions(-)

(limited to 'src')

diff --git a/src/modules/px4iofirmware/sbus.c b/src/modules/px4iofirmware/sbus.c
index 6ead38d61..23dae7898 100644
--- a/src/modules/px4iofirmware/sbus.c
+++ b/src/modules/px4iofirmware/sbus.c
@@ -80,8 +80,10 @@ static int sbus_fd = -1;
 
 static hrt_abstime last_rx_time;
 static hrt_abstime last_frame_time;
+static hrt_abstime last_txframe_time=0;
 
 static uint8_t	frame[SBUS_FRAME_SIZE];
+static uint8_t	oframe[SBUS_FRAME_SIZE];
 
 static unsigned partial_frame_count;
 
@@ -122,10 +124,39 @@ sbus_init(const char *device)
 void
 sbus1_output(uint16_t *values, uint16_t num_values)
 {
-	char a = 'A';
-	write(sbus_fd, &a, 1);
-}
+	//int. first byte of data is offset 1 in sbus
+	uint8_t byteindex=1;
+	uint8_t offset=0;
+	uint16_t value;
+	hrt_abstime	now;
+	//oframe[0]=0xf0;
+	oframe[0]=0x0f;
 
+        now = hrt_absolute_time();
+        if ((now - last_txframe_time) > 14000) {
+		last_txframe_time = now;
+
+		for (uint16_t i=1;i<SBUS_FRAME_SIZE;++i) {
+			oframe[i]=0;
+		}
+		// 16 is sbus number of servos/channels minus 2 single bit channels.
+		// currently ignoring single bit channels.
+		for (uint16_t i=0;(i<num_values)&&(i<16);++i) {
+			value=(uint16_t)(((values[i]-SBUS_SCALE_OFFSET+.5f)/SBUS_SCALE_FACTOR) +.5f);
+			//protect from out of bounds values and limit to 11 bits;
+			value&=0x07ff;
+			while (offset>=8) {
+				++byteindex;
+				offset-=8;
+			}
+			oframe[byteindex] |= (value<<(offset))&0xff;
+			oframe[byteindex+1]|=(value>>(8-offset))&0xff;
+			oframe[byteindex+2]|=(value>>(16-offset))&0xff;
+			offset+=11;
+		}	
+		write(sbus_fd, oframe, SBUS_FRAME_SIZE);
+	}
+}
 void
 sbus2_output(uint16_t *values, uint16_t num_values)
 {
-- 
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