Ground OSD work in progress

So, here we are for ground osd.

It's a fork of minimosd-extra. I've replaced Mavlink support for LightTelemetry.
Ghettostation repack & send LTM packets to the minimosd at 38400 bauds using softserial. ( I don't think going higher baudrate in softserial won't cause problems. )
I had some hard time to make softserial working with servos. It was causing big troubles because of Timer & interrupts problems.
Once I've moved the servo to PWMServo lib it worked like it should.

There's not much things changed in the original minimosd code for now But I will lighten it, there's lot of useless things on it for ground use.

You can see the actual result:

 

Sorry for the glitches, I have a wiring problem on this little quad.

So we have like 400ms lag when using audio telemetry. I'm still working on tricks to improve this, but it's already far usable.

edit: I've found a bug on my side.
There was a bottleneck in the serial stream at 2400 bauds. Too much data, I've forgotten to count the start/stop bit for each bytes ( we're communicating with 8n2 serial ).
So I've switched the GPS & Sensor frames at 2 hz and here we go :

Far better isn't it. :)

 I'm still fighting on a way to grab the RSSI from the naze32. For now there's no ADC support in baseflight ( I've encountered some bugs by hacking it for analog rssi ) , and pwm rssi only works when not using PPM mode. I hope Dongs will be able to give a look to this.
 No problem with Taulabs btw.

LightTelemetry v2: en route to ground OSD.

LTM protocol has been extended to prepare the future ground OSD for Ghettostation.
I think I have some pretty good refresh rate of all needed data for that purpose.
We now have 3 different frames:

- GPS frame (G): Latitude, Longitude, Ground Speed, Altitude, Number of sats, GPS fix type

- Attitude frame (A): Pitch, Roll, Heading

- Sensors/Status frame (S): Battery Voltage, Current consumed, RSSI, Airspeed,  Armed state, Failsafe state, Flight mode

	1200 bauds	2400 bauds+
G frame	2hz	5hz
A frame	5hz	10hz
S frame	2hz	5hz

GPS frame

0x24

0x54

0x47

0x00

0x00

0x00

0x00

0x00

0x00

0x00

0x00

0x00

0x00

0x00

0x00

0x00

0x00

0xFF

$

T

G

Latitude (degre*10000000)

Longitude (degre*10000000)

Ground Speed (m/s)

Altitude (cm)

first 2 bits: Fix last 6 bits: Sats

CRC xor byte 4 to 15

Start 1

Start 2

Frame ID

Payload

Checksum

Attitude frame

0x24	0x54	0x41	0x00	0x00	0x00	0x00	0x00	0x00	0xFF
$	T	A	Pitch (degre)		Roll (degre)		Heading (degre)		CRC xor byte 4 to 9
Start 1	Start 2	Frame ID	Payload						Checksum

Sensors/Status frame

0x24	0x54	0x53	0x00	0x00	0x00	0x00	0x00	0x00	0x00	0xFF
$	T	S	Vbat (mv)		Consumed current (ma)		RSSI	Airspeed (m/s)	1st bit: armed 2nd bit: failsafe latest: flight mode	CRC xor byte 4 to 10
Start 1	Start 2	Frame ID	Payload							Checksum

Ghettostation, Taulabs & Baseflight have all been updated to ltm v2 on my github.

You still can use my TL & BF builds here:  Google drive

There's almost no lag in the attitude data, that's a really good news, I was a bit afraid that such low baudrate would prevent a nice smooth horizon bar. 
Ground base OSD will be a really cool feature. Less cables on air seems better to me.