Key-Disp KD21C User manual

Contents
Productnameandmodel........................................................................................................ 1
AppearanceandSize............................................................................................................... 1
MaterialsandColor.................................................................................................................1
Function SummaryandButton Definition......................................................................... 2
FunctionSummary .................................................................................................................2
FunctionalArea Distribution................................................................................................2
ButtonDefinition.....................................................................................................................2
General Operation.................................................................................................................... 2
PowerOn/Off............................................................................................................................2
DisplayInterface......................................................................................................................3
PushCruiseControl...............................................................................................................3
Turnon/off Backlight .............................................................................................................3
PASLevel Selection...............................................................................................................4
BatteryIndicator......................................................................................................................4
ErrorCodeInformation..........................................................................................................4
GeneralSettings....................................................................................................................... 4
TripDistanceClearance........................................................................................................5
Backlight Contrastsettings..................................................................................................5
InchandMetricConversion................................................................................................5
GeneralParameterSettings .................................................................................................. 6
Wheel DiameterSettings.......................................................................................................6
Speed-limitSettings...............................................................................................................6
PersonalizedParameterSettings......................................................................................... 6
BatteryPowerBarSettings..................................................................................................7
PowerAssistantLevelSettings..........................................................................................7
PowerAssistantLevel Select..................................................................................................7
PASRatiosettings......................................................................................................................8
ControllerOver-CurrentCutSettings ...............................................................................8
PowerAssistantSensorSettings.......................................................................................8
The DirectionofPowerAssistant SensorSettings ..........................................................8
The SensitivityofPASSettings..............................................................................................9
Magnet quantitySettings.........................................................................................................9
SpeedSensorSelection........................................................................................................9
ThrottleDefinition.................................................................................................................10

ThrottleAssistance PushEnableorDisable.....................................................................10
ThrottleLevelEnableorDisable..........................................................................................10
SystemSettings.....................................................................................................................10
Delaytimesettingsof batterypower ..................................................................................10
Maxspeed limited.....................................................................................................................11
Button PASSettings ................................................................................................................11
PASSpeed Settings .................................................................................................................11
SlowlyStartupSettings..........................................................................................................12
Power-onPasswordSettings............................................................................................12
Power-on PasswordEnable...................................................................................................12
Power-on PasswordModify...................................................................................................13
Exitsettings............................................................................................................................13
Recoverdefaultsettings ...................................................................................................... 13
OperationCautions................................................................................................................ 14
Qualityassuranceand warrantyscope............................................................................ 14
、Warranty ..............................................................................................................................14
Ⅱ、Otheritems..........................................................................................................................14
Connection layout.................................................................................................................. 14

1
Productname andmodel
Electricbicycleintelligent LCDinstrument; model: KD21C.
Specifications
24V/36V/48VPower Supply
Rated current 10mA
The maximumworking current 30mA
Off leakage current <1uA
The supplycontroller workingcurrent 50mA
Operating temperature:-20 ~ 60
Storage temperature: -30 ~ 70
AppearanceandSize
MaterialsandColor
KD21Cproduct’sshelland hookaremadeofABS andNylon respectively.LCD
transparentwindowlens ishigh hardness acrylic.Between -20 and60 temperature,the
mechanicalperformances ofthe shell materialsareexcellent, which ensuretheusabilityof
theshell.
Displayappearanceanddimensionfigure(unit: mm)

2
FunctionSummaryandButtonDefinition
FunctionSummary
KD21Ccanprovidealotoffunctionstofittheusers’need.Theindicatingcontentsare
asfollowing.
BatteryIndicator
MotorPowerRatio
Powerassistleveladjustment Indicator
SpeedDisplay(includingrunning speed,max speed and averagespeed)
Tripdistanceandtotaldistance
6km/hCruisecontrol
Triptimedisplayofsingle
Headlight On/Off
ErrorCodeIndicator
VariousParametersSettings (likewheelsize,speed-limited,batterylevelbar, PAS
level,controllerlimitedcurrent, maxspeed,passwordenable,andsoon.)
RecoverDefault Settings
Functional Area Distribution
Functional area distribution
ButtonDefinition
Therearethree buttons(MODE, UPandDOWN) on the KD21Cdisplay,such as
respectively.
General Operation
PowerOn/Off
Hold MODE buttonthenthedisplay willpoweron.Inlike mannerhold MODE toturn
off powerwhen thedisplay working.Whenthedisplay offtheleakagecurrentislessthan1
uA.
■Whenparkinge-bike formorethan 10minutes, the displayshut downautomatically.

3
DisplayInterface
Afterstartingupthedisplay,default showisrunning speedandTotalDistance . Press
MODE tochangethe indicatedinformationinsequence asbelow: RunningSpeed (Km/h)
→TripDistance(km) →TotalDistance(km) →TravelTime(Hour.) →MaxSpeed (Km/h)
→AverageSpeed(Km/h) →MotorPower(W) →Running Speed(Km/h).
PushCruise Control
Hold DOWN for2secondstoenterthemode ofpowerassistant walk.The e-bikewill
go onat auniform speedof 6Km/hwhenyouholdDOWN always. Pshowson thescreen
atthesametime. Otherwise immediatelystop6km/houtputpowerwhenthe DOWN is
releasedandinterfacereturnsto themode beforethe powerassistantwalk.
PushCruisecontrol
■“PushCruiseControl”functioncanonlybeused topushthee-bikebyhands.
Pleasedon’t usethisfunctionwhenriding.
Turnon/off Backlight
Hold UP for2secondstoturnon the backlightofthedisplay,the headlightwill be
poweronatthesametime.Hold UP for2secondsagain,backlightwill be turned off.

4
TurnOn/Off Backlight
PASLevel Selection
Press UPorDOWN tochangetheoutputpower of themotor. Thedefault power ranges
fromlevel0 tolevel5.The outputpoweris0on Level0.Level1istheminimumpower.
Level5isthemaximumpower. Geartolevel5andthen press UP,the interface displays 5still
and 5flashingpromptingtop;Geartolevel0andthenpress DOWN,theinterfacedisplays0still
and 0flashingpromptinglow.Thedefaultvalueislevel1.
PAS Level3
BatteryIndicator
The6batterybarsrepresentthecapacityofthebattery.Whenthebatteryisinlow
voltage,batteryframewill flash tonotice thatthebatteryneedstoberecharged immediately.
LowVoltage Flash
Battery Indicator
ErrorCodeInformation
If thereareerrorsabouttheelectroniccontrolsystem,theerror codewill appear
automatically.Hereisthedetail informationof theerror codein Attached list 1.
Error Code Indicator
■Makethedisplayrepairedwhenerrorcode appears
General Settings

5
Hold MODE buttontostart thedisplay,thenholdboth UP and DOWN for2secondsto
enter generalsettings menu.
■AlltheSettingsareoperatedinthecase of zerospeed
TripDistanceClearance
TCmeans singletripdistance clearance settings,Press UP or DOWN tochoose YorN
tocleartripdistance. ThedefaultisN.Press MODE to confirm and enterbacklightcontrast
settings.Various symboldefinition refer to Attached list 4.
TripDistanceClearance SettingsInterface
Backlight Contrastsettings
bL means backlightcontrastsettings.Level1isthelowbrightness.Level2isthe
middlebrightness.Level3ishighbrightness.Thedefaultlevelis1.
Press UPorDOWN tomodifythebacklightbrightness.Press MODE toconfirmand
exitthegeneralsettings.
Backlight brightnessSettings Interface
Inchand MetricConversion
Umeans unit settings, 1isinch, 2ismetric.Press UP orDOWN tochange thenumber
toconvert. Press MODE toconfirmandenter backlight contrast settings. Hold MODE to
confirmandexit generalsettings. Udefault value is2.

6
InchandMetricConversionSettingsInterface
General Parameter Settings
Holdboth UP and DOWN for2seconds toenterUsersettings.Thenholdboth DOWN
and MODE morethan 2secondsistoenter wheeldiameterSettingsinterface.
WheelDiameterSettings
Ldmeanswheeldiametersettings.Selectablevaluesinclude16,18,20,22,24,26,700C
and 28.Press UP or DOWN toselectthecorrectvaluetomatchthewheeldiameter.
Defaultdiameter is20 inch. Press MODE to enter speed-limitsettings interface.
WheelDiameterSettingsInterface
Speed-limit Settings
LSmeansthelimitspeedsettings.When the runningspeedisfasterthanlimitspeed,
thecontrollerwill cutoff themotorpower. Limitspeedrange is12Km/hto40Km/h.Limit
speeddefaultvalueis25Km/h.Press UP or DOWN toselectthefavoritevalue,thenhold
MODE over2secondstoconfirmandquit thesettings mode.
LimitSpeedSettingsInterface
PersonalizedParameter Settings
PersonalizedParameterSettingscanmatchvarietyrequirementsinuse.Thereare8
Settingsitems,such as BatteryPowerBarSettings,PowerassistantlevelSettings,Over-
currentCutSettings ,PowerAssistantSensorSettings,SpeedSensorSettings，Throttle
Function Settings,SystemSettings and Power-on PasswordSettings.Please refertothe
Attachedlist2.

7
Holdboth UP and DOWN morethan 2secondstoentergeneralsettings,then hold
both UP and DOWN againtoenter personalizedparametersettingsitemsselectionpage.
Press UP or DOWN tochoosethe personalizedparametersettingsitems,andpress
MODE toenter thecorrespondingsettingspage.
OptionSelect Interface
BatteryPowerBarSettings
VOL meansvoltagesettings.Each barrepresentsavoltagevalue.5voltagevalues
mustbe enteredonebyone. Forexample,VOL1isfirstbar voltagevalue, thedefault
valueis31.5.Press UP or DOWN toincrease orreduce the number. Press MODE to
confirmandenterthesecond bar. Byanalogy, after5
voltagevaluesisentered,hold
MODE toconfirm andreturntoprevious menu.
BatteryPowerBar Settings
PowerAssistant Level Settings
PowerAssistant Level Select
Inpowerassistantlevelsettings,thereare8modestoselect：0-3,1-3,0-5,1-5,0-7,
1-7,0-9,1-9.The defaultmode is0-5.Press UP orDOWN toselectthemode,andpress
MODE toconfirmandenter the PASratiosettings page.

8
1-5 flash
PAS Mode SelectInterface
PASRatiosettings
Tomodifythevalueof PASratiocanmatch thedifferent requirements.
Forexample, therangeis “45-55percent”of 1level, bottom valuecan bemodified, and
thedefaultis50percent. Press MODE toconfirmandturntothenextPASratiosettings.
After all PASratioinputted,hold MODE toconfirmandreturntopreviousmenu,please refer
to Attached list3.
PAS Ratio Interface
ControllerOver-CurrentCutSettings
CURmeanscontrollerover-current cutsettings. CUR valuecanbe changedfrom 7.0A
to22.0A.Press UP orDOWN tochangethevalueofthecurrent, andhold MODE to
confirmthesettings andreturntopreviousmenu. Default valueof controller over-current cut
is15A.
CURSettings Interface
PowerAssistant SensorSettings
TheDirectionof PowerAssistant SensorSettings
PASmeanspowerassistantsensorsettings. “run-F”meansforwarddirection,while
“run-b”meansbackdirection.Press UP orDOWN toselectForb,andpress MODE to

9
confirmandentersettingsmode ofPASsensitivity,thedefaultdirectionis“run-F”.
Directionof PAS Sensor Settings
TheSensitivityof PASSettings
SCNmeansthesensitivityofPASsettings.The sensitivityvalue is2to9.2isthe
strongest, 9istheweakest. Press UP or DOWN toselectsensitivityvalue,andpress
MODE toconfirmselectionandentermagnetdisksettingsmode.ThesensitivityofPAS
defaultvalueis2.
The SensitivityofPAS Settings
Magnet quantitySettings
NmeansmagnetnumbersofPASdisk.Press UP orDOWN toselectquantity
corresponding toPASdisk.Magnetquantitydefault valueis6.
PAS MagnetDisk Settings
SpeedSensorSelection
SPSmeansspeedsensorsettings.Press UP or DOWN toselectthequantityof
magnethead(therangeisfrom1to9), andhold MODE toconfirmandreturntoprevious
menu.SPS defaultvalueis1.

10
SpeedSensor Selection
ThrottleDefinition
ThrottleAssistance PushEnableorDisable
HLmeansthrottleassistance push. HL-Nmeans throttleassistance pushfunctionis
disabled. HL-Ymeans throttleassistance pushfunction isenabled. Press UP orDOWN to
select Y, and press MODEtoconfirmthe selection. Otherwise select Ntoenter Throttle
LevelEnableSettings, HLdefault value isN.
ThrottleEnable/Disable Interface
ThrottleLevel EnableorDisable
HF-Ymeans throttlelevelisenabled, HF-Nmeans throttlelevelisdisabled. Press UP
orDOWN toselect Yor N, and press MODE toconfirmand enter ThrottleEnableSettings
page.HoldMODEtoconfirmandreturntoprevious menu. HFdefault value isN.
ThrottleLevelEnableor Disable Interface
SystemSettings
Delaytimesettingsofbatterypower
DLYmeansdelaytimeofbatterypowersettings.Press UP or DOWN toselectdelay
time3,6,12s, thenpress MODE toconfirmand enterthemaxspeedlimited. Thedefault
timeis3s.

11
Delaytimeof batterypower interface
Maxspeedlimited
MAXSPDmeansmaxspeedlimited settings.Press UPorDOWN toSetthemax
speed from25Km/h~40Km/h.Press MODE toconfirmandenterButtonPASSettings. The
defaultis40Km/h.
Interfaceofmaxspeedlimited settings
■Thissettings isthepriorityversion.Thespeedisthemaximumsettedby
manufacturer.
ButtonPASSettings
PUSmeansbuttonpushsettings.Press UP or DOWN tochooseYorN.Ymeans
buttonpushisenabled,N means button push isdisabled.Press MODE toconfirmand
enter PASspeedsettings.Thedefaultvalueis Y.
Interfaceof PAS push
PASSpeedSettings
Adjustpush speedbysettingsPAS tomeetrider’srequirements.Press UPorDOWN
to adjustfrom 20%to35%, press MODE toconfirm andenterslowlystart up.Defaultvalue
is25%.

12
Interfaceof PAS speed settings
SlowlyStart up Settings
SSPmeans slowlystart up.Therange is1-4,4istheslowest. Press UP orDOWN to
choose,press MODE toconfirmand turntoDelay timesettingsofbatterypowerpage.
Hold MODE toconfirmandreturntoprevious menu. Thedefaultvalueis1.
Interfaceof slowlysettingsup
Power-onPasswordSettings
P2,0000 onthescreenmeanspower-on passwordsettings.Press UP or DOWN to
changethenumber. Press MODE toconfirmdigitonebyone.After correct4-digitpassword
entered,press MODE toconfirmandenterpower-on passwordenablesettings
interface,otherwisestayon the passwordinputstate.The defaultpower-onpasswordis
2222.
Power-onPasswordEnteringInterface
Power-onPasswordEnable
Press UP or DOWN toselect YorN, andpress MODE toconfirm.Power-onPassword
defaultisN. If itisY, press MODE toenterpower-on passwordmodifyinterface ,otherwise
exit the power-onpasswordsettings interface.
YisPower-onPasswordEnable
NisPower-onPasswordDisable

13
Power-onPasswordDisable Interface
Power-onPasswordModify
When thedisplayshowsP3,0000,press MODE tochoosedigitonebyone,press UP
or DOWN toinputthe newpassword,thenhold MODE toconfirmthemodification and exit
settings. Restartingdisplay will show P1,0000, inputthe new passwordtopower on.
Power-on PasswordModify Interface
Exit settings
Inthesettings state,pressing MODE (less than2s) istoconfirmtheinput. Holding
MODE (morethan2s) istosavethesettings,and thenexit the currentsettings.Holding
DOWN (morethan2s)istocanceltheoperatingbutnot savingsettings data,and then
returntoprevious menu.
■If thereisnot anyoperationsinoneminute,displaywill exit thesettings state.
Recoverdefaultsettings
dEFmeansrecover default settings.Press both UP and MODE morethan2seconds to
enterrecoverdefaultsettings.Press UP or DOWN tochoose YorN. Nmeansthatdo not
recoverdefault settings.Ymeansthatrecoversdefault settings.When itisY,hold MODE to
recoverdefaultsettings,the displayshowsDEF-00atthe sametime, and then returnto
generaldisplaystate. ThedefaultstateisN.
RecoverDefaultSettings Interface

14
OperationCautions
Becareofthe safetyuse. Don’t attempt torelease the connector whenbatteryison power.
Trytoavoidhitting.
Don’tsplitthewaterproof sticker to avoidaffectingthewaterproofperformance.
Don’t modifysystemparameterstoavoidparametersdisorder.
Make thedisplay repaired whenerror codeappears.
Qualityassuranceand warrantyscope
、Warranty
1 、Any qualityproblemsinnormalcase andduringguaranteeperiod,ourcompany
will beresponsiblefor thewarranty.
2、Thewarrantytimeis24months whendisplay outof thefactory.
Ⅱ、Otheritems
Thefollowingitemsdonot belongtoour warrantyscope.
1、It cannotbedemolished.
2、Thedamage iscausedbywronginstallationor operation.
3、Shellisbrokenwhendisplay isoutof thefactory.
4、Wireisbroken.
5、BeyondWarrantyperiod.
6、The fault ordamageiscaused bytheforce majeure(such asfire, earthquake, etc,)
or naturaldisasterslike lighting, etc.
Connectionlayout
Connector linesequence
Display-side ConnectorDisplay-sideadapterSwitchwiring

15
Linesequence table
Line Color Function
1 Red（VCC）+
2 Blue(K) Lock
3 Black(GND) -
4 Green(RX) RX
5 Yellow(TX) TX
■Somewireusethewater-proof connector,users can not seetheinsidecolor.
Attachedlist1：Errorcode definition
Attachedlist 2: PersonalityParametersettings
Error Code Definition
21 Current Abnormality
22 Throttle Abnormality
23 Motor Abnormality
24 MotorHall Signal Abnormality
25 Brake Abnormality
30 Communication Abnormality
No.
Settingsitem
Screendisplay
1 BatteryPowerBar Settings
2 PowerassistantlevelSettings
3 Over-current CutSettings
4 PowerAssistantSensorSettings
5 SpeedSensorSettings
6 Throttle FunctionSettings
7 SystemSettings
8 Power-onPasswordSettings

16
Attachedlist3：Powerassist table
Attachedlist4：symbol definition
No. Symbol Definition
1 Tripdistanceclearance
2 Backlight
3 Unit
4 Voltage
5 Wheeldiameter
6 Speedlimit
7 Controllerover-current cut
8 Backward
9 Forward
10 SensitivityofPAS
11
S
peedsensor
12 Powerdelayedtime
13 Throttle powerassist walk
14 Throttle-changing
15 Buttonpush

17
16 Slowlystart up
17 Password
18 Recoverdefault
19 Yes
20 No