DIY drone: Lesson 4. Flight controller.DIY drone: Lesson 4. Flight controller.

Content

Introduction

Now that you have select­ed or designed the UAV frame, select­ed the motors, rotors, ESC and bat­tery, you can pro­ceed to select the flight con­troller. A flight con­troller for a mul­ti-rotor drone is an inte­grat­ed cir­cuit, usu­al­ly con­sist­ing of a micro­proces­sor, sen­sors, and input/output con­tacts. After unpack­ing, the flight con­troller does not know what spe­cif­ic type or con­fig­u­ra­tion of the UAV you are using, so you will ini­tial­ly need to set cer­tain para­me­ters in the soft­ware, after which the spec­i­fied con­fig­u­ra­tion is loaded on board. Rather than sim­ply com­par­ing the cur­rent­ly avail­able flight con­trollers, the approach we’ve tak­en here lists which PC ele­ments are respon­si­ble for which func­tions, as well as aspects to look out for.

Main Processor

DIY drone: Lesson 4. Flight controller.DIY drone: Lesson 4. Flight controller.

8051 vs AVR vs PIC vs ARM: A fam­i­ly of micro­con­trollers that form the basis of most mod­ern flight con­trollers. The Arduino is based on the AVR (ATmel) and the com­mu­ni­ty seems to be focused on the Mul­ti­Wii as the code of choice. Microchip is the main man­u­fac­tur­er of PIC chips. It’s hard to argue that one is bet­ter than the oth­er, it all comes down to what the soft­ware can do. ARM (e.g. STM32) uses 16/32-bit archi­tec­ture, with dozens using 8/16-bit AVRs and PICs. As sin­gle board com­put­ers become less and less expen­sive, a new gen­er­a­tion of flight con­trollers are expect­ed that can run full oper­at­ing sys­tems such as Lin­ux or Android.

CPU: Usu­al­ly their bit width is a mul­ti­ple of 8 (8‑bit, 16-bit, 32-bit, 64-bit), which in turn indi­cates the size of the pri­ma­ry reg­is­ters in the CPU. Micro­proces­sors can only process a set (max­i­mum) num­ber of bits in mem­o­ry at a time (cycle). The more bits the micro­proces­sor can process, the more accu­rate (and faster) the pro­cess­ing will be. For exam­ple, pro­cess­ing a 16-bit vari­able on an 8‑bit proces­sor is much slow­er than on a 32-bit one. Note that the code must also work with the cor­rect num­ber of bits, and at the time of this writ­ing, few pro­grams use code that is opti­mized for 32 bits.

Work­ing fre­quen­cy: The fre­quen­cy at which the main proces­sor is run­ning. It is also referred to by default as “clock speed”. Fre­quen­cy is mea­sured in hertz (cycles per sec­ond). The high­er the oper­at­ing fre­quen­cy, the faster the proces­sor can process data.

Pro­gram Memory/Flash: Flash mem­o­ry is where the main code is stored. If the pro­gram is com­plex, it can take up a lot of space. Obvi­ous­ly, the larg­er the mem­o­ry, the more infor­ma­tion it can store. The mem­o­ry is also use­ful for stor­ing in-flight data such as GPS coor­di­nates, flight plans, auto­mat­ic cam­era move­ment, etc. The code loaded on the flash mem­o­ry remains on the chip even after the pow­er is turned off.

SRAM: SRAM stands for “Sta­t­ic Ran­dom Access Mem­o­ry” and is the space on a chip that is used when per­form­ing cal­cu­la­tions. Data stored in RAM is lost when the pow­er is turned off. The high­er the amount of RAM, the more infor­ma­tion will be “eas­i­ly avail­able” for cal­cu­la­tions at any giv­en time.

EEPROM: elec­tri­cal­ly erasable pro­gram­ma­ble read-only mem­o­ry (EEPROM) is typ­i­cal­ly used to store infor­ma­tion that does not change dur­ing flight, such as set­tings, as opposed to data stored in SRAM, which may include sen­sor read­ings, etc.

Addi­tion­al I/O Ports: most micro­con­trollers have a large num­ber of dig­i­tal and ana­log input and out­put ports, on the flight con­troller some are used for sen­sors, oth­ers for com­mu­ni­ca­tion, or for gen­er­al input and out­put. RC ser­vos, gim­bal sys­tems, buzzers and more can be con­nect­ed to these addi­tion­al ports.

Ana­log-to-dig­i­tal con­vert­er (A/D converter/ADC): If the sen­sors use an on-board ana­log volt­age (typ­i­cal­ly 0–3.3V or 0–5V), an A/D con­vert­er must con­vert these read­ings to dig­i­tal data. As with the proces­sor, the num­ber of bits that can be processed by the ADC deter­mines the max­i­mum pre­ci­sion. Relat­ed to this is the clock rate at which the micro­proces­sor can read data (num­ber of times per sec­ond) to make sure no infor­ma­tion is lost. How­ev­er, it is dif­fi­cult not to lose some data dur­ing this con­ver­sion, so the high­er the bit width of the ADC, the more accu­rate the read­ings will be, but it is impor­tant that the proces­sor can cope with the speed at which the data is sent.

Food

DIY drone: Lesson 4. Flight controller.DIY drone: Lesson 4. Flight controller.

Often a flight con­troller spec­i­fi­ca­tion describes two volt­age ranges, the first of which is the input volt­age range of the flight con­troller itself (most oper­ate at a nom­i­nal volt­age of 5V), and the sec­ond is the input volt­age range of the main micro­proces­sor (3.3V or 5V). Because the flight con­troller is an embed­ded device, you only need to pay atten­tion to the input volt­age range of the con­troller. Most mul­ti-rotor UAV flight con­trollers oper­ate at 5V, which is the volt­age gen­er­at­ed by the BEC (see the Pow­er­plant sec­tion for more infor­ma­tion).

Let’s repeat. Ide­al­ly, you don’t need to pow­er the flight con­troller sep­a­rate­ly from the main bat­tery. The only excep­tion is if you need a back­up bat­tery in case the main bat­tery is putting out so much pow­er that the BEC can’t pro­duce enough current/voltage, caus­ing a pow­er outage/reset. But, in this case, capac­i­tors are often used instead of a back­up bat­tery.

Sensors

In terms of hard­ware, the flight con­troller is essen­tial­ly a reg­u­lar pro­gram­ma­ble micro­con­troller, only with spe­cial sen­sors on board. At a min­i­mum, the flight con­troller will include a 3‑axis gyro­scope, but with­out auto-lev­el­ling. Not all flight con­trollers are equipped with the fol­low­ing sen­sors, but they can also include a com­bi­na­tion of them:

  • Accelerom­e­ter: As the name sug­gests, accelerom­e­ters mea­sure lin­ear accel­er­a­tion along three axes (let’s call them X, Y, and Z). Usu­al­ly mea­sured in “G (in Russ­ian Zhe)”. The stan­dard (nor­mal) val­ue is g = 9.80665 m/s². To deter­mine the posi­tion, the out­put of the accelerom­e­ter can be inte­grat­ed twice, how­ev­er, due to the loss in the out­put, the object may be sub­ject to drift. The most sig­nif­i­cant char­ac­ter­is­tic of tri­ax­i­al accelerom­e­ters is that they reg­is­ter grav­i­ty, and as such, can know in which direc­tion to “descent”. This plays a major role in ensur­ing the sta­bil­i­ty of a mul­ti-rotor UAV. The accelerom­e­ter must be mount­ed on the flight con­troller so that the lin­ear axes coin­cide with the main axes of the drone.

DIY drone: Lesson 4. Flight controller.DIY drone: Lesson 4. Flight controller.

  • Gyro­scope: The gyro­scope mea­sures the rate of change of angles along three angu­lar axes (let’s call them: alpha, beta and gam­ma). Usu­al­ly mea­sured in degrees per sec­ond. Note that the gyro­scope does not mea­sure absolute angles direct­ly, but you can iter­ate to get an angle that, like the accelerom­e­ter, favors drift. The out­put of a real gyro­scope tends to be ana­log or I2C, but in most cas­es you don’t need to wor­ry about this since all incom­ing data is han­dled by the flight con­troller code. The gyro­scope must be installed so that its rota­tion axes coin­cide with the axes of the UAV.

DIY drone: Lesson 4. Flight controller.DIY drone: Lesson 4. Flight controller.

  • Iner­tial Mea­sure­ment Unit (IMU): An IMU is essen­tial­ly a small board that con­tains both an accelerom­e­ter and a gyro­scope (usu­al­ly mul­ti-axis). Most of them include a 3‑axis accelerom­e­ter and a 3‑axis gyro­scope, oth­ers may include addi­tion­al sen­sors, such as a 3‑axis mag­ne­tome­ter, pro­vid­ing a total of 9 mea­sure­ment axes.

DIY drone: Lesson 4. Flight controller.DIY drone: Lesson 4. Flight controller.

  • Compass/Magnetometer: An elec­tron­ic mag­net­ic com­pass capa­ble of detect­ing the Earth­’s mag­net­ic field and using this data to deter­mine the direc­tion of the drone’s com­pass (rel­a­tive to the north mag­net­ic pole). This sen­sor is almost always present if the sys­tem has GPS input and one to three axes are avail­able.

DIY drone: Lesson 4. Flight controller.DIY drone: Lesson 4. Flight controller.

  • Pressure/Barometer: Since atmos­pher­ic pres­sure changes as you move away from sea lev­el, you can use a pres­sure sen­sor to get a fair­ly accu­rate read­ing of the UAV’s alti­tude. To cal­cu­late the most accu­rate alti­tude, most flight con­trollers receive data from both a pres­sure sen­sor and a satel­lite nav­i­ga­tion sys­tem (GPS). When assem­bling, please note that it is prefer­able that the hole in the barom­e­ter body be cov­ered with a piece of foam rub­ber, this will reduce the neg­a­tive effect of wind on the chip.

DIY drone: Lesson 4. Flight controller.DIY drone: Lesson 4. Flight controller.

  • GPS: The Glob­al Posi­tion­ing Sys­tem (GPS) uses sig­nals from mul­ti­ple satel­lites in orbit around the Earth to deter­mine your spe­cif­ic geo­graph­ic loca­tion. The flight con­troller can have either a built-in GPS mod­ule or a cable-con­nect­ed one. The GPS anten­na should not be con­fused with the GPS mod­ule itself, which can look like a small black box or a reg­u­lar “Duck” anten­na. To get accu­rate loca­tion data, the GPS mod­ule must receive data from sev­er­al satel­lites, and the more the bet­ter.

DIY drone: Lesson 4. Flight controller.DIY drone: Lesson 4. Flight controller.

  • Dis­tance: Dis­tance sen­sors are increas­ing­ly used on drones because GPS coor­di­nates and pres­sure sen­sors can­not tell you how far you are from the ground (hill, moun­tain, or build­ing) or whether you will col­lide with an object or not. The down­ward fac­ing dis­tance sen­sor can be based on ultra­son­ic, laser or lidar tech­nol­o­gy (IR sen­sors may expe­ri­ence prob­lems in sun­light). Dis­tance sen­sors are rarely includ­ed as stan­dard with a flight con­troller.

DIY drone: Lesson 4. Flight controller.DIY drone: Lesson 4. Flight controller.

Flight modes

Below is a list of the most pop­u­lar flight modes, how­ev­er not all of them may be avail­able on the flight con­trollers. “Flight Mode” is the way in which the flight con­troller uses sen­sors and incom­ing radio com­mands to ensure the sta­bi­liza­tion and flight of the UAV. If the con­trol equip­ment used has five or more chan­nels, the user can con­fig­ure the soft­ware, which will allow him to change modes through chan­nel 5 (aux­il­iary switch) direct­ly dur­ing the flight.

  • ACRO — usu­al­ly the default mode, of all avail­able sen­sors, only the gyro­scope is used by the flight con­troller (the drone can­not auto­mat­i­cal­ly align). Rel­e­vant for sports (acro­bat­ic) flight.
  • ANGLE — sta­ble mode; of all avail­able sen­sors, the gyro­scope and accelerom­e­ter are used by the flight con­troller. cor­ners are lim­it­ed. Will keep the drone lev­el (but not hold the posi­tion).
  • HORIZON — com­bines the sta­bil­i­ty of the ANGLE mode, when the sticks are near the cen­ter and move slow­ly, and the acro­bat­ics of the ACRO mode, when the sticks are in the extreme posi­tions and move quick­ly. The flight con­troller uses only the gyro­scope.
  • BARO (Alti­tude Hold) — sta­ble mode; of all avail­able sen­sors, the flight con­troller uses a gyro­scope, an accelerom­e­ter, and a barom­e­ter. cor­ners are lim­it­ed. The barom­e­ter is used to hold a cer­tain (fixed) alti­tude when no com­mands are giv­en from the con­trol equip­ment.
  • MAG (Head­ing Hold) — course lock mode (com­pass direc­tion), the drone will keep Yaw ori­en­ta­tion. Of all the avail­able sen­sors, the flight con­troller uses a gyro­scope, an accelerom­e­ter, and a com­pass.
  • HEADFREE (Care­Free, Head­less, Head­less) — elim­i­nates the ori­en­ta­tion track­ing (Yaw) of the drone and thus allows you to move in the 2D direc­tion accord­ing to the move­ment of the ROLL/PITCH con­trol stick. Of all the avail­able sen­sors, the flight con­troller uses a gyro­scope, an accelerom­e­ter, and a com­pass.
  • GPS/Return to Home — auto­mat­i­cal­ly uses the com­pass and GPS to return to the take­off point. Of all the avail­able sen­sors, the flight con­troller uses a gyro­scope, an accelerom­e­ter, a com­pass, and a GPS mod­ule.
  • GPS/Waypoint — allows the drone to autonomous­ly fol­low pre-set GPS points. Of all the avail­able sen­sors, the flight con­troller uses a gyro­scope, an accelerom­e­ter, a com­pass, and a GPS mod­ule.
  • GPS/Position Hold — Holds the cur­rent posi­tion using GPS and barom­e­ter (if avail­able). Of all the avail­able sen­sors, the flight con­troller uses a gyro­scope, an accelerom­e­ter, a com­pass, and a GPS mod­ule.
  • Fail­safe (emergency/failsafe mode) — if no oth­er flight modes have been set, the drone switch­es to Acro mode. Of all the avail­able sen­sors, only the gyro­scope is used by the flight con­troller. Rel­e­vant in case of fail­ures in the drone soft­ware, allows you to restore con­trol over the UAV through pre­vi­ous­ly pre­set com­mands.

Software

PID con­troller (appoint­ment and set­ting)

Pro­por­tion­al Inte­gral Derivate (PID) or Pro­por­tion­al-Inte­gral-Deriv­a­tive (PID) con­troller — a piece of flight con­troller soft­ware that reads data from the sen­sors and cal­cu­lates how fast the motors must rotate in order to main­tain the desired speed of the UAV.

Devel­op­ers of ready-to-fly UAVs tend to tune the PID con­troller para­me­ters opti­mal­ly, so most RTF drones fly per­fect­ly right out of the box. The same can­not be said about cus­tom UAV builds, where the actu­al use of a uni­ver­sal flight con­troller suit­able for any mul­ti-rotor build, with the abil­i­ty to adjust the PID val­ues ​​until they cor­re­spond to the required flight char­ac­ter­is­tics of the end user.

DIY drone: Lesson 4. Flight controller.DIY drone: Lesson 4. Flight controller.

GUI

Graph­i­cal User Inter­face (GUI) or Graph­i­cal User Inter­face — this is what is used to visu­al­ly edit the code (using a com­put­er) that will be loaded into the flight con­troller. The soft­ware that comes with flight con­trollers keeps get­ting bet­ter and bet­ter; ear­ly flight con­trollers used most­ly text-based inter­faces that required users to under­stand almost all of the code and change cer­tain sec­tions to fit the design. Recent­ly, inter­ac­tive graph­i­cal inter­faces have been used in the GUI, in order to make it eas­i­er for the user to con­fig­ure the nec­es­sary para­me­ters.

DIY drone: Lesson 4. Flight controller.DIY drone: Lesson 4. Flight controller.

Addi­tion­al fea­tures

The soft­ware used on some flight con­trollers may have addi­tion­al fea­tures that are not avail­able on oth­ers. The choice of a par­tic­u­lar flight con­troller may ulti­mate­ly depend on what addi­tion­al features/functionality is offered by the devel­op­er. The list of such func­tions may include:

  • Offline way­point nav­i­ga­tion — allows the user to set GPS way­points that the drone will fol­low autonomous­ly.
  • Oribit­ing — mov­ing the drone around a giv­en GPS coor­di­nate, where the front of the drone is always direct­ed towards the giv­en coor­di­nate (rel­e­vant for shoot­ing).
  • fol­low me — many UAVs have the “Fol­low Me / Fol­low me” func­tion, which can be based on satel­lite posi­tion­ing (for exam­ple, track­ing the GPS coor­di­nates of a smart­phone, or a GPS mod­ule built into the con­trol equip­ment).
  • 3D image — most of the 3D imag­ing is done after the flight using images and GPS data obtained dur­ing the flight.
  • open source — soft­ware of some flight con­trollers can­not be changed/configured. Open source prod­ucts gen­er­al­ly allow advanced users to mod­i­fy the code to suit their spe­cif­ic needs.

Connection

Radio con­trol (RC)

Con­trol via radio usu­al­ly includes an RC trans­mit­ter / RC trans­mit­ter (in an unmanned hob­by — radio con­trol equip­ment / remote con­trol) and an RC receiv­er (RC receiv­er). To inter­act with the UAV, the user will need at least four (or more) chan­nel RC trans­mit­ter. By default, the first four chan­nels are asso­ci­at­ed with:

  • Throttle/Elevation (take­off and descent)
  • Yaw (rota­tion around its axis left and right)
  • Pitch (for­ward and back­ward move­ment)
  • Roll (move left and right)

DIY drone: Lesson 4. Flight controller.DIY drone: Lesson 4. Flight controller.

All oth­er avail­able chan­nels can be used for such actions as:

  • Arm­ing (Arm­ing or Arm) / Dis­arm­ing (Dis­arm­ing or Dis­arm) — set­ting / dis­arm­ing motors.
  • Gim­bal con­trol (pan up/down, rotate clockwise/counterclockwise, zoom)
  • Change of flight modes (ACRO / ANGLE, etc.)
  • Activate/Engage pay­load (para­chute, buzzer or oth­er device)
  • Any oth­er use

DIY drone: Lesson 4. Flight controller.DIY drone: Lesson 4. Flight controller.

Most users (UAV pilots) pre­fer man­u­al con­trol, which proves once again that pilot­ing with the help of con­trol equip­ment is still the num­ber one choice. By itself, the RC receiv­er sim­ply trans­mits the val­ues ​​​​incom­ing from the RC trans­mit­ter, which means it can­not con­trol the drone. The RC receiv­er must be con­nect­ed to the flight con­troller, which in turn must be pro­grammed to receive RC sig­nals. There are very few flight con­trollers on the mar­ket that accept incom­ing radio com­mands direct­ly from the receiv­er, and most PCs even pro­vide pow­er to the receiv­er from one of the pins. Addi­tion­al con­sid­er­a­tions when choos­ing a remote con­trol include:

  • Not all RC trans­mit­ters can pro­vide the full range of RC sig­nals from 500ms to 2500ms; some arti­fi­cial­ly lim­it this range, as most of the RCs in use are for RC cars, air­planes, and heli­copters.
  • Range/Max. air range (mea­sured in feet or meters) RC sys­tems almost nev­er pro­vid­ed by man­u­fac­tur­ers, since this para­me­ter is influ­enced by many fac­tors, such as inter­fer­ence, tem­per­a­ture, humid­i­ty, bat­tery pow­er, and oth­ers.
  • Some RC sys­tems have a receiv­er that also has a built-in trans­mit­ter to trans­mit data from the sen­sor (such as GPS coor­di­nates) which will then be dis­played on the LCD of the RC trans­mit­ter.

Blue­tooth

Blue­tooth and lat­er BLE (Blue­tooth Low Ener­gy) prod­ucts were orig­i­nal­ly designed to trans­fer data between devices with­out the has­sle of pair­ing or match­ing fre­quen­cies. Some flight con­trollers on the mar­ket can send and receive data wire­less­ly via a Blue­tooth con­nec­tion, mak­ing trou­bleshoot­ing eas­i­er in the field.

DIY drone: Lesson 4. Flight controller.DIY drone: Lesson 4. Flight controller.

WiFi

Wi-Fi con­trol is usu­al­ly achieved through a Wi-Fi router, com­put­er (includ­ing lap­top, desk­top, tablet) or smart­phone. Wi-Fi is able to han­dle both data trans­fer and video stream­ing, but at the same time, this tech­nol­o­gy is more dif­fi­cult to set up / imple­ment. As with all Wi-Fi devices, the dis­tance is lim­it­ed by the Wi-Fi trans­mit­ter.

DIY drone: Lesson 4. Flight controller.DIY drone: Lesson 4. Flight controller.

Radio fre­quen­cy (RF or RF)

Radio fre­quen­cy (RF) con­trol in this con­text refers to the wire­less trans­mis­sion of data from a com­put­er or micro­con­troller to an air­craft using an RF transmitter/receiver (or dual band trans­ceiv­er). Using a con­ven­tion­al RF unit con­nect­ed to a com­put­er allows two-way com­mu­ni­ca­tion over long dis­tances with a high “den­si­ty” of data (usu­al­ly in ser­i­al for­mat).

DIY drone: Lesson 4. Flight controller.DIY drone: Lesson 4. Flight controller.

Smart­phone

Although this is not a type of com­mu­ni­ca­tion, the very ques­tion of how to con­trol a drone using a smart­phone is enough to give it a sep­a­rate sec­tion. Mod­ern smart­phones are essen­tial­ly pow­er­ful com­put­ers that, coin­ci­den­tal­ly, can also make phone calls. Almost all smart­phones have a built-in Blue­tooth mod­ule as well as a WiFi mod­ule, each of which is used to con­trol the drone and/or receive data and/or video.

DIY drone: Lesson 4. Flight controller.DIY drone: Lesson 4. Flight controller.

Infrared radi­a­tion (Infrared (IR))

Infrared (some­thing found in every TV remote con­trol) is rarely used to con­trol drones, as even in nor­mal rooms (not to men­tion open spaces) there is so much infrared inter­fer­ence that they are not very reli­able. Although the tech­nol­o­gy can be used to con­trol UAVs, it can­not be offered as a main­stream option.

DIY drone: Lesson 4. Flight controller.DIY drone: Lesson 4. Flight controller.

Additional Considerations

Func­tion­al­i­ty: Flight con­troller man­u­fac­tur­ers usu­al­ly try to pro­vide as many fea­tures as pos­si­ble — either includ­ed by default or pur­chased sep­a­rate­ly as options / add-ons. The fol­low­ing are just a few of the many addi­tion­al fea­tures you might want to look at when com­par­ing flight con­trollers.

Damp­ing: even small vibra­tions in the frame, usu­al­ly caused by unbal­anced rotors and/or motors, can be detect­ed by the built-in accelerom­e­ter, which in turn will send appro­pri­ate sig­nals to the main proces­sor, which will take cor­rec­tive action. These minor fix­es are not nec­es­sary or desir­able for sta­ble flight, and it is best to keep the flight con­troller vibrat­ing as lit­tle as pos­si­ble. For this rea­son, vibra­tion dampers/dampers are often used between the flight con­troller and the frame.

Frame: a pro­tec­tive case around the flight con­troller can help in a vari­ety of sit­u­a­tions. In addi­tion to being more aes­thet­i­cal­ly pleas­ing than a bare PCB, the pack­age often pro­vides some lev­el of elec­tri­cal pro­tec­tion. ele­ments, as well as addi­tion­al pro­tec­tion in the event of a crash.

Mount­ing: There are var­i­ous ways to mount a flight con­troller to a frame, and not all flight con­trollers have the same mount­ing options:

  1. Four holes 30.5mm or 45mm apart squared.
  2. Flat bot­tom for use with a stick­er.
  3. Four holes in a rec­tan­gle (stan­dard not estab­lished).

Com­mu­ni­ty: Since you are build­ing a cus­tom drone, par­tic­i­pat­ing in the online com­mu­ni­ty can help a lot, espe­cial­ly if you run into prob­lems or want advice. Get­ting rec­om­men­da­tions from the com­mu­ni­ty or look­ing at user feed­back on the qual­i­ty and ease of use of var­i­ous flight con­trollers can also be help­ful.

Acces­sories: In order to ful­ly use the prod­uct, in addi­tion to the flight con­troller itself, relat­ed items (acces­sories or options) may be required. Such acces­sories may include, but are not lim­it­ed to: a GPS mod­ule and/or a GPS anten­na; cables; mount­ing acces­sories; screen (LCD/OLED);

Example

So with all these dif­fer­ent com­par­isons, what infor­ma­tion can you get about a flight con­troller and what can a flight con­troller include? We have cho­sen the Quadri­no Nano Flight Con­troller as an exam­ple.

Main Processor

The ATMel used onboard the ATMega2560 is one of the most pow­er­ful Arduino com­pat­i­ble ATMel chips. Although it has a total of 100 pins, includ­ing 16 A/D chan­nels and five SPI ports, due to its small size and intend­ed use as a flight con­troller, only a few are present on the board.

  • AVR vs PIC: AVR
  • Proces­sor: 8‑bit
  • Oper­at­ing fre­quen­cy: 16MHz
  • Pro­gram Memory/Flash: 256KB
  • SRAM: 8KB
  • EEPROM: 4KB
  • Addi­tion­al I/O pins: 3 × I2C; 1 x UART 2 x 10-pin GPIOs; Ser­vo with 5 × out­puts; OLED port
  • Ana­log to Dig­i­tal Con­vert­er: 10-bit

DIY drone: Lesson 4. Flight controller.DIY drone: Lesson 4. Flight controller.

Sensors

The Quadri­no Nano includes the MPU9150 IMU chip, which includes a 3‑axis gyro­scope, 3‑axis accelerom­e­ter, and 3‑axis mag­ne­tome­ter. This helps keep the board small enough with­out sac­ri­fic­ing sen­sor qual­i­ty. The MS5611 barom­e­ter pro­vides pres­sure data and is cov­ered with a piece of foam. Inte­grat­ed Venus 838FLPx GPS with exter­nal GPS anten­na (includ­ed).

DIY drone: Lesson 4. Flight controller.DIY drone: Lesson 4. Flight controller.

Software

The Quadri­no Nano was cre­at­ed specif­i­cal­ly to use the lat­est Mul­ti­Wii soft­ware (Arduino based). Instead of mod­i­fy­ing the Arduino code direct­ly, sep­a­rate, more graph­i­cal soft­ware was cre­at­ed.

DIY drone: Lesson 4. Flight controller.DIY drone: Lesson 4. Flight controller.

Connection

  • Direct input from a stan­dard RC receiv­er.
  • Spek­trum Ded­i­cat­ed Satel­lite Receiv­er Port
  • Ser­i­al (SBus and/or Blue­tooth or 3DR radio)

DIY drone: Lesson 4. Flight controller.DIY drone: Lesson 4. Flight controller.

Additional factors

  1. Frame: Pro­tec­tive translu­cent hous­ing includ­ed as stan­dard
  2. Mount­ing: There are two main ways to attach the Quadri­no Nano to your drone: screws and nuts, or a foam rub­ber stick­er.
  3. Com­pact design: the con­troller itself (with­out tak­ing into account the GPS anten­na) has dimen­sions of 53 × 53mm.

DIY drone: Lesson 4. Flight controller.DIY drone: Lesson 4. Flight controller.

Yara

By Yara