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KTM-S88

RK3399 development board for all-in-one digital signage and signage players. Hexa-core (2 × Cortex-A72 + 4 × Cortex-A53) with LVDS / EDP / MIPI display, HDMI 2.0a in and out, CAN, Type-C USB 3.0 and a wide serial set on a 160 × 120 mm board.

This page is the hardware reference

Flashing, the firmware API and the guides apply to every board. This page covers what is specific to the KTM-S88: its connectors, pin assignments and electrical limits.

Connector map​

RK3399A72 + A53160 × 120 mmDC-12VRJ45HDMI outHDMI inUSB3.0USB2.0AudioDC-12V-INCANRS485-1RS485-2USB1-412V-OUTEDP-BLEDPTP-I2CLVDSLVDS-BLMICSPKRS232×3IR/LEDGPIO×6GPIO-KEY

Swipe sideways to see the whole board. Tap a connector to jump to its pin definition. Positions are schematic, not to scale.

Specification​

OSAndroid 8.1
CPURockchip RK3399 — dual-core Cortex-A72 up to 1.8 GHz + quad-core Cortex-A53 up to 1.5 GHz
GPUARM Mali-T864
DDRLPDDR4 4 GB
FlasheMMC 5.0, 32 GB (16 GB / 64 GB / 128 GB optional)
Wi-Fi802.11 a/b/g/n/ac, 2×2 MIMO, dual 2.4 / 5 GHz
EthernetRJ45 gigabit (1000 M)
Screen interfaceLVDS, EDP
HDMIHDMI 2.0a out (4K) and HDMI 2.0a in
Type-CUSB 3.0 Type-C
RTCYes — with scheduled power on/off
Audio / Mic3.5 mm earphone and microphone
CameraVia USB

Power: DC 12 V / 3 A via 5.5 × 2.1 mm barrel (current depends on screen size).

note

The datasheet is inconsistent on supply current: the specification table lists 12 V / 3 A, while the "Other ports" summary (§3.19) and the electrical specification both list 2 A. Size your supply for the higher figure and confirm with us before relying on 2 A.

Internal expansion: LVDS, EDP, MIPI (each with power/backlight), 3 × RS232, 2 × RS485, CAN, 4 × USB, speaker, LED/IR, 8 × GPIO and a touch-panel header.

Board dimensions​

Size160 mm × 120 mm
Thickness16 mm
Top clearance1.6 mm
Bottom clearance3.0 mm

Serial ports at a glance​

The RS232 and RS485 headers are driven through the standard serial interface. The datasheet does not give a /dev/ttyS* node for them.

PortDevice nodeType
RS232-1—RS232, full duplex
RS232-2—RS232, full duplex
RS232-3—RS232, full duplex
RS485-1—RS485, half duplex
RS485-2—RS485, half duplex

The RS232/RS485 device nodes are not specified in the datasheet. Confirm on your board with ls /dev/ttyS* or contact us. The board also has a CAN header (§3.9). See the firmware API overview for how the device API drives the board (power scheduling, GPIO, display, network, kiosk lockdown).

Display ports​

3.1 LVDS port — dual-contact 30-pin, 2.0 mm​

PinDefineAttributeDescription
15VPower out3.3V / 5V / 12V optional
212VPower out3.3V / 5V / 12V optional
33.3VPower out3.3V / 5V / 12V optional
4GNDGNDGround
5GNDGNDGround
6GNDGNDGround
7D0NOutputPixel 0 negative data (odd)
8D0POutputPixel 0 positive data (odd)
9D1NOutputPixel 1 negative data (odd)
10D1POutputPixel 1 positive data (odd)
11D2NOutputPixel 2 negative data (odd)
12D2POutputPixel 2 positive data (odd)
13GNDGNDGround
14GNDGNDGround
15CLK0NOutputNegative sampling clock (odd)
16CLK0POutputPositive sampling clock (odd)
17D3NOutputPixel 3 negative data (odd)
18D3POutputPixel 3 positive data (odd)
19D5NOutputPixel 0 negative data (even)
20D5POutputPixel 0 positive data (even)
21D6NOutputPixel 1 negative data (even)
22D6POutputPixel 1 positive data (even)
23D7NOutputPixel 2 negative data (even)
24D7POutputPixel 2 positive data (even)
25GNDGNDGround
26GNDGNDGround
27CLK1NOutputNegative sampling clock (even)
28CLK1POutputPositive sampling clock (even)
29D8NOutputPixel 3 negative data (even)
30D8POutputPixel 3 positive data (even)

3.4 EDP port — dual-contact 20-pin, 2.0 mm​

PinDefineAttributeDescription
1VCCVCC—
2VCCVCC—
3GNDGNDGround
4GNDGNDGround
5EDP_TX0NDifference dataChannel 0
6EDP_TX0PDifference dataChannel 0
7EDP_TX1NDifference dataChannel 1
8EDP_TX1PDifference dataChannel 1
9EDP_TX2NDifference dataChannel 2
10EDP_TX2PDifference dataChannel 2
11EDP_TX3NDifference dataChannel 3
12EDP_TX3PDifference dataChannel 3
13GNDGNDGround
14GNDGNDGround
15XNData clockDifference signal
16XPData clockDifference signal
17GNDGNDGround
18GNDGNDGround
19GNDGNDGround
20NCNCNC

3.18 MIPI port — FPC 0.5 mm, 40-pin​

PinDefineAttributeDescription
1NCNCNC
2–3VCCPower in1.8V / 3.3V
4GNDGNDGround
5Mipi-RST_LResetReset
6NCNCNC
7GNDGNDGround
8MIPI_D0NTX-D0NDifference data, channel 0
9MIPI_D0PTX-D0PDifference data, channel 0
10GNDGNDGround
11MIPI_D1NTX-D1NDifference data, channel 1
12MIPI_D1PTX-D1PDifference data, channel 1
13GNDGNDGround
14MIPI_CLKNTX_CLKNSampling clock
15MIPI_CLKPTX_CLKPSampling clock
16GNDGNDGround
17MIPI_D2NTX-D2NDifference data, channel 2
18MIPI_D2PTX-D2PDifference data, channel 2
19GNDGNDGround
20MIPI_D3NTX-D3NDifference data, channel 3
21MIPI_D3PTX-D3PDifference data, channel 3
22GNDGNDGround
23–24NCNCNC
25GNDGNDGround
26–29NCNCNC
30GNDGNDGround
31–32LEDK-LED cathodeBL-LED-VCC −
33–38NCNCNC
39–40LEDALED anodeBL-LED-VCC +

Backlight and display power​

3.2 LVDS power port — 6-pin, 2.0 mm​

Selects the LVDS panel supply voltage by jumper.

PinDefineAttributeDescription
13.3VLVDS VCC3.3V
2VCC-LVDSLVDS VCC3.3V
35VLVDS VCC5V
4VCC-LVDSLVDS VCC5V
512VLVDS VCC12V
6VCC-LVDSLVDS VCC12V

3.5 EDP power port — 6-pin, 2.0 mm​

PinDefineAttributeDescription
13.3VLVDS VCC3.3V
2VCC-LVDSLVDS VCC3.3V
35VLVDS VCC5V
4VCC-LVDSLVDS VCC5V
512VLVDS VCC12V
6VCC-LVDSLVDS VCC12V

3.3 LVDS backlight control port — PH2.0-6P​

PinDefineAttributeDescription
1VCCPower out12V
2VCCPower out12V
3BL-ENOutputBacklight enable
4BL-ADJOutputBacklight adjust
5GNDGNDGround
6GNDGNDGround

3.6 EDP backlight control port — PH2.0-6P​

PinDefineAttributeDescription
1VCCPower out12V
2VCCPower out12V
3BL-ENOutputBacklight enable
4BL-ADJOutputBacklight adjust
5GNDGNDGround
6GNDGNDGround

Power​

3.7 12V-out power port — PH2.54-4P​

Supplies 12 V out to a peripheral (per the datasheet title, "VCC12V - Out Power Port").

note

The datasheet title marks this as a 12 V output, but its pins are labelled "Power in" (identical to the external power port at §3.8). Confirm the direction before wiring — do not feed the board and a peripheral into the same rail blindly.

PinDefineAttributeDescription
112VPower in12V
212VPower in12V
3GNDGNDGround
4GNDGNDGround

3.8 External power port — PH2.54-4P​

PinDefineAttributeDescription
112VPower in12V
212VPower in12V
3GNDGNDGround
4GNDGNDGround

CAN bus​

3.9 CAN port — PH2.0-4P​

PinDefineAttributeDescription
1CAN_VSSCAN_VSSCAN ground
2CAN-LCAN LCAN low
3CAN-HCAN HCAN high
4VCCPower out5V

Serial ports​

The RS232 and RS485 headers are driven through the standard serial interface. The device API (ItempApiPub) does not handle UART I/O; it covers power, display, GPIO, network and kiosk.

3.10 RS485 (×2) port — PH2.0-4P​

Two RS485 headers share this pinout.

PinDefineAttributeDescription
1GNDGNDGround
2RS485-AI/OUART0 A
3RS485-BI/OUART0 B
4VCCPower out3.3V

3.12 RS232 (×3) port — PH2.0-4P​

Three RS232 headers share this pinout.

PinDefineAttributeDescription
1GNDGNDGround
2TXI/OUART0 TX
3RXI/OUART0 RX
4VCCPower out3.3V

USB ports​

Four internal USB headers, identical pinout (PH2.0-4P).

3.11 USB (×4) port — PH2.0-4P​

PinDefineAttributeDescription
1GNDGNDGround
2DPI/OUSB D+
3DMI/OUSB D−
4VCCPower out5V

Audio​

3.13 Speaker port — PH2.0-4P​

PinDefineAttributeDescription
1LPOutputLeft positive
2LNOutputLeft negative
3RNOutputRight negative
4RPOutputRight positive

LED, IR and control​

3.14 LED / IR port — PH2.0-5P​

PinDefineAttributeDescription
1LED_RLED redLED red
2LED_GLED greenLED green
3VCCPower out3.3V
4GNDGNDGround
5IR INInputIR input

GPIO​

These are the pins the GPIO API drives. The SDK names (GPIO_IO1 … GPIO_IO8) match the Define column below.

3.15 GPIO-KEY port — PH2.0-4P​

PinDefineAttributeDescription
1GNDGNDGround
2GPIO_IO7I/OGPIO_IO7
3GPIO_IO8I/OGPIO_IO8
4KEYPower keyPower key

3.16 GPIO ×6 port — PH2.0-8P​

PinDefineAttributeDescription
1GNDGNDGround
2GPIO_IO6I/OGPIO_IO6
3GPIO_IO5I/OGPIO_IO5
4GPIO_IO4I/OGPIO_IO4
5GPIO_IO3I/OGPIO_IO3
6GPIO_IO2I/OGPIO_IO2
7GPIO_IO1I/OGPIO_IO1
8VCC-3.3VVCCVCC-3.3V

Eight user GPIO lines (GPIO_IO1–GPIO_IO8), a power-key line and a 3.3 V rail. See GPIO for reading and driving these from code.

Touch panel​

3.17 I2S port — FPC 0.5 mm, 10-pin​

note

The datasheet titles this connector "I2S", but its pins (RST, INT, SCL, SDA) are a touch-panel I2C interface, not an I2S audio bus. Treat it as touch-panel I2C and verify with us before wiring an I2S device to it.

PinDefineAttributeDescription
1GNDGNDGround
2GNDGNDGround
3RSTResetReset
4INTInterruptInterrupt
5GNDGNDGround
6SCLSCLI2C clock
7SDASDAI2C data
8VCCVCC3.3V
9GNDGNDGround
10GNDGNDGround

Other interfaces​

3.19 Other ports​

InterfaceDetail
PowerDC 5.5 × 2.1 mm barrel, 12 V / 2 A
HDMI outHDMI 2.0a
HDMI inHDMI 2.0a
EthernetRJ45, gigabit (1 G)
USB1 × USB 2.0, 1 × USB 3.0
Audio / Mic3.5 mm earphone and microphone
TF cardUp to 64 GB

Electrical specification​

ParameterMinTypicalMaxNotes
Power supply voltage—12V—
Ripple voltage——85 mV
Power supply current—2 A—Depends on screen size
Power consumption—24 W—Depends on screen size

API reference​

The device API (power scheduling, GPIO, display, network, kiosk lockdown) is documented under ItempApi reference. The serial ports above are driven through the standard Android serial interface.

Downloads​

Schematic, mechanical drawing and firmware image are on the KTM-S88 support page.