MultiWii 23 was the culmination of years of break-thru drone autopilot "pilot feel" development used in our PARIS v5r3 and PARIS AIR Herov2 autopilots - the core "ACRO" component of this software that is now ported over to CleanFlight -  However the smoothness and pilot friendly nature of MultiWii 23 is still enjoyed by pilots TODAY in the Scarab Knife 270 trainer for FPV HERE  

Below you can read the main changes in MultiWii Open source software for user updating 2.2 -> 2.3  Make SURE YOU USE the 2.3 GUI if your PARIS shipped with 2.3 - using the 2.2 GUI will corrupt all data on the PARIS !!     http://www.multiwii.com/forum/viewtopic.php?f=8&t=4246

PARIS v5r3 now ships with 2.3 open source code - if you want to know which of these vast raft of possible features is enabled or not you can read the Sketches yourself as the software is open source using the Free Arduino 1.0.5 HERE on a Mac or a PC!! Many of the topics below are NOT relevant to PARIS - they all relate to SOFTWARE - Multicopters fly 100% by software - We assume no responsibility for Open Source code or it's function.  If not sure about software - do NOT change it.

If you are a coder - PLEASE join in and make a contribution of your ideas to the code base - adopting a take, take, take attitude to SOFTWARE is not part of the spirit of open sauce (sic) -  this code is the result of many smart coders "getting" involved and contributing for the benefit of all and giving, giving, giving of their time - a team of people contributing - working for a better result than any "one" person can achieve - it is really sad to see talented coders go all selfish, and say they will never contribute - ultimately we sell HARDWARE to support this open source project - so coders lurking in the shadows - I recommend you step forward and get noticed for your talent ! We have ourselves at MultiWiiCopter contributed to the code base writing the Octa motor mixes.

Whats NEW?  
v2.3 ***Control mode***

1. main PITCH/ROLL/YAW PID modification (r1474)
2. the sticks scaling is no more affected by PID coefficients
3. yaw rate (to the right of the PIDs in GUI) now works as stick scaling
4. default yaw rate is increased (with yaw rate at 0)
5. yaw PID principle is now different from PITCH&ROLL PID:
6. yaw ITerm windup is very high, allowing an 'elastic' direction return after a manual perturbation
7. yaw ITerm is also constrained with a windup independent limit
8. yaw PTerm is constrained in order to counter the yaw jump effect.
9. use yaw DTerm to increase this constrain (r1573)
10. yaw ITerm is canceled if the yaw stick is not centered
11. Throttle angle correction (r1374)
12. Advanced Headfree mode added (see config.h for instructions) (r1374)
13. DYNBALANCE option, individual motor can be controled via GUI, to test individual vibration viewtopic.php?f=7&t=3294
14. better gyro & acc calibration accuracy (r1546) viewtopic.php?f=7&t=3880
15. cannot arm is baro mode is on (r1550) viewtopic.php?f=8&t=3910  baro mode should be activated only when the multi is nearly Z stable ! 
16. only one baro mode : vario around a throttle deadband (r1554)
17. magHold is reset when arm is switched on (r1553) viewtopic.php?f=8&t=3910
18. ONLY ARM WHEN FLAT option (r1587) viewtopic.php?f=8&t=4077&hilit=coming&start=40#p41755

v2.3 ***receiver & UART***

1. RCSERIAL is now deeply integrated. If a MSP_SET_RAW_RC comes, it will just override legacy RX data. (r1420)
2. as a consequence, RCSERIAL is no more an option
3. no RC averaging for Spektrum & SBUS (r1545)
4. SBUS center define (r1568) viewtopic.php?f=8&t=3957
5. FAILSAFE_DETECT_TRESHOLD configurable

v2.3 ***GPS***

1. Enables sonar altitude from i2c-gps-nav board (1424)
2. navigation code will follow after 2.3

v2.3 ***GUI***

1. Gui with Servosettings. (r1441 & r1450)
2. All models with servo included.
3. GUI globalsettings (for some settings previously only in config.h)
4. do not display /dev/cu.* devices but only corresponding /dev/tty.* (r1442)
5. GUI baudrate as configurable setting

v2.3 ***LCD***

1. lcd.telemtry: show max ground speed from gps data (r1398)
2. lcd.telemetry: allow separate suppression of aux2 configuration (r1456)
3. new display support 1.3" i2c OLED from digole.com (r1413)
4. config.menu: when abort, revert all values back to last saved state
5. visual feedback from servos during midpoint trim via LCD

v2.3 ***IMU and baro***

1. correct GYRO_SCALE for all gyro (r1428)
2. no more small angles while shaking the board (r1579) viewtopic.php?f=8&t=4112
3. baro Alt based on ground temp compensation (r1570) viewtopic.php?f=8&t=4059
4. not I reset for FIWEDWING (r1590) viewtopic.php?f=7&t=2456&start=330#p42355
5. add 6DOF LSM330 sensor (r1571)
6. add ACC BMA280 sensor (r1600)

v2.3 *** SERVO management ***

1. warning:The pins for coptertypes with servos have been changed. Attaching a servo to a motor pin can quickly destroy your servo. All connection diagrams out there from v2.2 or older are no longer valid for v2.3 with servos using hardware PWM. http://www.multiwii.com/wiki/index.php? ... figuration
2. add 8 hardware PWM's for servos on MEGA boards. Servo outputs are 44,45,46,11,12,6,7,8 (r1384)
3. Allow any servo refresh rate from 20 to 400Hz on Mega hardware PWM servos. (r1386)
4. Tri servo moved to SERVO4 (pin11) on mega boards with HW PWM's. (r1392)
5. a32u4 (PARIS AIR) HW PWM for 4 servos; warning different pins!!(with lots of info and help from ronco)(r1464 & r1470)
6. add a generic way to configure servo settings : conf struct + MSP read/set messages (r1383)
7. Added general servo handler (r1421 & r1429) viewtopic.php?f=8&t=3498
8. allow preset of some servo stuff from config.h (r1432)
9. Gui with Servosettings. (r1441)
10. add gimbal servo stretcher usable with HW PWM's. (r1384)
11. We can get 180 degrees servo move without servo modification.
12. note about gimbal: settings for neutral&endpoints are no more in config.h, but only in GUI
13. do not update servos during unarmed calibration of sensors which are sensitive to vibration (r1408)

v2.3 ***internal improvements***

1. migration to a cpp/h code structure (r1515 & r1516) viewtopic.php?f=8&t=3773   viewtopic.php?f=8&t=2931
2. huge flash size optimization (around 1k) thanks to fine struct definitions + serialization over MSP (r1369)
3. make powermeter computation time based (again) to reduce config hassle and increase accuracy (r1375)
4. read at most one analog channel per MWii main loop cycle (r1375)
5. smoothing of RX_RSSI (r1379)
6. make faster analog reads an option with default off to increase accuracy (r1375)
7. detangle vbat & buzzer dependancy (r1375)
8. optimization : small approximation bit shift used instead of * or / number
9.   for TPA, rates, dynP, dynD and expo curb (r1376)
10. Added checking for flash content change, and reload config parameters in this case. (r1389)
11. Split Serial into Serial(core UART management) & Protocol (r1548)
12. Loop is globally faster