Description

SW900 LCD Display for Electric Bike – eBike Screen 24V–72V with UART Protocol for Conversion Kits

Name: SW900 LCD Display for E-Bike Conversion Kits
Brand: All4ebikes
SKU: 26

SW900 LCD display with large screen, multi-voltage 24V–72V compatibility and standard UART protocol. Shows real-time current, average and maximum speed, battery level, PAS level (0–9), trip and total distance (TRIP & ODO), motor wattage and error codes E0–E13. Included as standard in All4eBikes MTX kits 250W–3000W and available as a spare part or upgrade.

24V – 72V UART Protocol PAS 0–9 Levels Speed / ODO / WATT Error Codes E0–E13 ABS Shell IP65

The SW900 is one of the most widely used displays for eBike conversion kits. The large LCD screen provides good readability even in direct sunlight, and the ABS shell with high-hardness acrylic screen (equivalent hardness to tempered glass) withstands intensive use and varying weather conditions. The three buttons — Up (+), M (Mode) and Down (−) — allow adjusting assist level, navigating menus and accessing all configuration parameters without tools or external apps.

Technical Specifications

Electrical Parameters

Operating voltage24V / 36V / 48V / 60V / 72V

Communication protocolStandard UART

Connector wires7-wire (standard connector)

USB charging port5V / 500mA

Protection ratingIP65

Operating temperature−20°C / +70°C

Shell materialABS + high-hardness acrylic

Handlebar mount22.2 mm / 25.4 mm

Displayed Information

Current / MAX / AVG speedYes (switchable)

Speed unitkm/h or mph

Battery levelYes (bar indicator)

Active PAS level0–9 levels

Trip distance (TRIP)Yes

Total distance (ODO)Yes (resettable)

Instant motor power (WATT)Yes

Error codesE0–E13

Programmable Settings

System voltage (P03) ▷ set according to your battery voltage24V / 36V / 48V / 52V / 72V

Wheel diameter (P06)Settable in inches (0.1 prec.)

Speed limit (P08)0–50 km/h (50 = no limit)

PAS levels (P05)3 or 5 levels

Drive mode (P10)PAS / Throttle / Both

PAS sensitivity (P11)1–24

Controller current limit (P14)1–20A (default 12A)

6 km/h cruise (WALK)Yes (button activation)

Wire Colours – 7-Wire SW900 Connector

The SW900 uses a 7-wire connector. Wire colours and functions — useful for troubleshooting or reconnection:

Wire colour	Code	Function
Red	D+	Power positive
Black	GND	Power negative (ground)
Blue	DS	Controller electric door lock signal
Brown	DD+	Lighting control positive (if controller supports it)
Green	RX	UART communication receive (data display ← controller)
Yellow	TX	UART communication transmit (data display → controller)
White	GND	Lighting control negative (headlight ground)

Note: The brown (DD+) and white (lighting GND) wires are only needed if your controller supports software-controlled lighting. If not, leave them unconnected or insulate the ends.

Riding Modes

The SW900 supports 5 riding modes, selectable via parameter P10 or switchable while riding:

ECO — Economic

Reduced power, minimum consumption, maximum range. Best for flat urban commuting at low speed.

STD — Standard

Default mode. Balanced power-to-consumption ratio for everyday mixed-terrain use.

POWER — Full Power

All available power, higher consumption. Hills, difficult terrain or heavy loads.

SPEEDHANDLE — Throttle Only

Speed controlled exclusively by throttle. PAS disabled. Enabled via P10=1.

WALK — Walk Assist

Constant 6 km/h push assist for walking the bike alongside you — stairs, tight spaces, uphill pushing.

Three-Button Operation

Short press = under 1 second. Long press = hold for 2–3 seconds.

M

Button M — Mode / Menu

Short: cycle multi-function zone data (ODO → TRIP → WATT → Error)
Long: power screen on / off
In menu — Short: move to next parameter and save current
In menu — Long: save all and exit menu

+

Button Up — Plus / Increase

Short (riding): PAS level +1
Short (in menu): increase parameter value
Long: cycle speed display mode: current → MAX → AVG
Up + Down simultaneously 3–4 sec: enter settings menu P01–P16

−

Button Down — Minus / Decrease

Short (riding): PAS level −1
Short (in menu): decrease parameter value
Up + Down simultaneously 3–4 sec: enter settings menu P01–P16
Long (bike stopped): activate WALK mode 6 km/h — release to exit
Long: toggle headlight on / off

Auto-save: if no button is pressed for 10 seconds while in the settings menu, all modified values are saved automatically and the display exits the menu.

Error Codes E0–E13

Error codes appear in the multi-function zone of the screen. Code E0 means normal operation. Any other code indicates a specific condition:

Code	Status	Recommended action
E0	Normal — no error	—
E1	Save operation active	Informational, no action needed
E2	Brakes applied — motor cut off	Fully release the brake levers
E3	PAS fault (not implemented in current firmware)	Informational
E4	6 km/h cruise (WALK) active	Informational — WALK mode engaged
E5	Real-time cruise control active	Informational — cruise engaged
E6	Battery undervoltage	Charge battery. Verify voltage setting in P03 matches your battery
E7	Motor fault	Check motor ↔ controller connections (3-phase wires + Hall sensors)
E8	Throttle fault	Check throttle wiring. Possible short circuit or mechanical defect
E9	Controller fault	Check controller power supply and main connections
E10	Communication receive error	Check green wire (RX) between display and controller
E11	Communication transmit error	Check yellow wire (TX) between display and controller
E12	BMS battery communication error	Check battery connection and BMS status
E13	Headlight fault	Check headlight wiring and white wire (lighting GND)

Programmable Parameters P01–P16

Enter menu: press Up + Down simultaneously for 3–4 seconds. Navigate: short M. Adjust: Up / Down. Save & exit: long M.

Param	Function	Values / Notes
P01	Screen backlight brightness	1 = darkest \| 3 = brightest
P02	Distance unit	0 = Kilometres (KM) \| 1 = Miles (MILE)
P03	System voltage	24V / 36V / 48V / 52V / 72V. Default: 36V. Set according to your battery voltage.
P04	Auto sleep / standby time	0 = no sleep \| 1–60 = minutes until automatic power-off
P05	Number of PAS levels	0 = 3 levels (2V / 3V / 4V) \| 1 = 5 levels (2V / 2.5V / 3V / 3.5V / 4V)
P06	Wheel diameter	In inches, precision 0.1. Examples: 26.0 / 27.5 / 29.0
P07	Speed sensor magnets	Range: 1–100. Check your kit’s speed sensor specifications
P08	Speed limit	0–50 km/h. 50 = no limit. Applies to PAS; throttle may be unrestricted in non-communication mode
P09	Zero Start / Non-zero Start	0 = Zero Start (pedal before motor engages) \| 1 = Non-zero Start (motor engages immediately)
P10	Drive mode	0 = PAS only \| 1 = throttle only \| 2 = PAS + throttle (throttle disabled at zero start)
P11	PAS sensitivity	1–24. Lower values = faster motor response to pedalling input
P12	PAS start power	0–5. Motor power level at the first detected PAS signal
P13	PAS magnet type	3 options: 5 / 8 / 12 magnets. Check your PAS sensor (All4eBikes standard: 12)
P14	Controller current limit	1–20A. Default: 12A. Increase gradually if you need more starting torque
P15	Not implemented	Reserved for future firmware. Do not modify.
P16	Reset total odometer (ODO)	Long-press M button for 5 seconds to reset total distance to zero

Quick setup for All4eBikes MTX kits: P03 → 48V | P06 → your wheel diameter | P05 → 1 (5 PAS levels) | P08 → 50 (no limit, for off-road use).

Compatibility and Use Cases

Replacement Display

Direct replacement for the SW900 included in any All4eBikes MTX kit 250W–3000W. Same UART protocol, same connector, identical mounting.

Display Upgrade

Upgrade from a basic LED display or limited information screen to a full LCD with speed, ODO, WATT, error codes and 16 programmable parameters.

DIY UART Builds

Essential component for any DIY conversion with a UART controller — compatible with 17A, 22A, 26A, 35A, 45A and 60A controllers from the All4eBikes range.

Protocol compatibility: SW900 works exclusively with UART-protocol controllers. It is not compatible with KT controllers (proprietary protocol) or Bafang (different UART dialect). All controllers included in All4eBikes kits are directly compatible.

Frequently Asked Questions

What should I set up first after installation?

Enter the menu (hold M + Up for 2–3 sec) and set P03 to your system voltage (48V for All4eBikes MTX kits). Then set P06 to your exact wheel diameter in inches (26.0, 27.5 or 29.0) for accurate speed. The display ships defaulted to 36V and 26 inches.

Why does E6 appear when the battery is fully charged?

Error E6 (undervoltage) most commonly appears when the voltage set in P03 does not match the actual battery voltage. If your battery is 48V but P03 is set to 36V, the display will interpret the battery as discharged. Enter the menu and set P03 to your system’s correct voltage.

How do I switch between km/h and mph?

Enter the menu and navigate to P02. Set 0 for kilometres or 1 for miles. The speed display and distance counters convert automatically. Important: the value stored in P08 (speed limit) remains in km/h internally — update it after changing units if you have a speed limit set.

How do I activate WALK mode (6 km/h assist)?

With the bike completely stopped, hold the Down (−) button for 2–3 seconds. The motor will engage at exactly 6 km/h. Release the button to exit WALK mode. The screen will show informational code E4 while WALK mode is active.

Is the SW900 compatible with my controller?

SW900 works with any controller that uses standard UART protocol. All controllers in the All4eBikes range (17A–60A) are directly compatible. If you have a KT or Bafang controller, verify the protocol before ordering — these may use different protocols incompatible with SW900.