Class 1 - Zepto


The Zepto board is a certified PCB that integrates the modular ecosystem. This board is a modular machine focused on multimedia capable to support one Core, one Master Module and two Slave Modules. It is not a simple computer with multimedia features, it is the most upgradable device you will find on the market. It gives the opportunity to easily assemble your machine according not only to your needs, but to your imagination.

The most common communication features such as WiFi, BLE, Ethernet and USB ports are available on board. But there are no limits on the Zepto capabilities: LoRa, ZigBee, movement sensing, GPS..., all those are available on standard Modules. The only thing you need is connect them on the corresponding slots. If there is a need for more processing power, you don't need to replace the Zepto, the only thing you have to do is to replace the Core for another more powerful.

The next figure show a 3D view for the Zepto board.

Zepto 3D Top v1.png Zepto 3D Bottom v1.png

As a summary, the following table indicates the main features:

Zepto Key Features
Multi-platform single-board computer
It combine the power of a high-end processor (Core module) with uController (Master modules) on the same motherboard
1x Core
2x Slave sockets and 1x Master sockete
100 pins expansion headers
RGB and LVDS display FPC connectors
3.5 mm audio jack
SD card
6x USB


  • Mini-PC
  • Media center
  • Router
  • IoT
  • WiFi/BT access point
  • NAS
  • Education

Board specifications

Key features

The Zepto board has been designed as to be the most upgradeable and customizable computer device in the market using the modular architecture. This board offers a huge amount of multimedia and communications capabilities such as HDMI, USB, Ethernet, WiFi, Bluetooth and Bluetooth Low Energy (BLE). The Zepto is not limited only to these features, the board also includes two sockets for Slaves Modules, one socket for Master Modules and one socket for Cores. This brings a countless amount of customization options. The block diagram shows the parts that make it possible.

Zepto Block Diagram v1.png

The following figures identify the main parts of the board. The most important parts will be explained with more details in the next sections.

Zepto Description Top.png

Zepto Description Bottom v1.png Core

The Central Processing Unit (CPU), RAM, PMIC among other auxiliary elements are embedded on the core, a small standardized board designed to be connected on the core socket. Look on the description image to see where this socket is placed. On the following link you can find the currently available Cores. Store.

Core Exynos v2.jpg Modules

Lots of Modules focused in different areas such as communications, sensing or storage, are available. The Zepto board allows to connect a maximum of three standard Modules: two slave modules and one master module. Look at here to choose the desired module to convert your Zepto in the device you want. Note that if a memory module is used, it should be connected on the module socket module 1.

Modules v2.jpg


Two memory options are available for the Zepto board: a micro SD card and a Memory eMMCXX Module. The eMMC memory modules used to be faster than the SD cards, but it occupies one module socket. The user should choose either one or other. In order to allow that, the on board header should be connected as follows:

  • eMMC bootloader: Disconnect the jumper on the header. The eMMC module should be plugged on the module socket "Module 1".
  • Micro SD card bootloader: connect a jumper on the header.

Zepto Memory Top v1.png Zepto Memory Bottom v1.png



There are available nine USB 2.0 ports on the Zepto board and all are working as a host except one that works as Master Module OTG. Note that there are two USB B-Type connectors on the board, but these ports are used only as a supply source. See the "Power" section for more details.

It is available an Ethernet port that can carry traffic at the nominal rate of 100Mbit/s, supporting full and half-duplex with flow control.

There is also a header where you can connect a CAN bus, a ICSP connector for programming and debugging the Master Module plugged on the board and two header boxes with all the Master Module signals. The following tables shows the pinout of the these connectors.

CAN bus
Pin Funtion
5 CAN_V+

Six solder pads are available to configure the CAN bus. The functionality is explained next:

  • SJ1: Open it if the board is a node in the middle of the CAN bus.
  • SJ2 and SJ3: Select the signal source between SPI CAN controller or directly from the Core.
  • SJ4: Selects the working voltaje on the CAN bus between VSYS and 3.3V.
  • SJ5 and SJ6: Bridge them if you want the CAN bus GND will be the same of the Zepto GND.
Pin Function Pin Function
H1 H2
Pin Signal Pin Signal Pin Signal Pin Signal
1 IO47, SDA1 50 IO0 1 AD11 50 AD4
2 IO46, SCL1 49 IO1 2 AD10 49 AD5
3 IO45, LPUART.RX/RXD2, SPIFI_IO3 48 IO2 3 AD9 48 AD6
4 IO44, LOPUART.TX/TX2, SPIFI_IO2 47 IO3 4 AD8 47 AD7
5 IO43, SPI1_MOSI, SPIFI_IO1 46 IO4 5 GND 46 GND
6 IO42, SPI1_MISO, SPIFI_IO2 45 IO5 6 IO35, TRST 45 RXD0
7 IO41, SPI1_CLK, SPIFI_CLK 44 IO6 7 IO34, CAN1_RX 44 TDX0
8 IO40, SPI1_SS, SPIFI_CS 43 IO7 8 IO33, CAN1_TX 43 RXD1
9 GND 42 GND 9 IO32, 1-WIRE/SWP 42 TXD1
10 IO39, TMS/SWDIO 41 IO8 10 USB_Module_P 41 SDA0
11 IO38, TCK/SWCLK 40 IO9 11 USB_Module_N 40 SCL0
12 IO37, TDO/SWO 39 IO19 12 USB_ID 39 SPI_MOSI
13 IO36, TDI 38 IO11 13 CLK_32KHz 38 SPI_MISO
14 1V8 37 IO12 14 BAT_RTC 37 SPI_SCK
15 2V8 36 IO13 15 VBAT 36 SPI_SS
16 35 IO14 16 35 RESET
17 3V3 34 IO15 17 34 GND
18 33 VSYS 18 IO31, SDIO0_DATA1 33 IO16, I2S_SDI
19 32 19 IO30, SDIO0_DATA0 32 IO17, I2S_SDO, SDIO1_DATA1
20 VIO_REF 31 20 IO29, SDIO0_CLK 31 IO18, I2S_SCLK, SDIO1_DATA0
21 AREF 30 GND 21 IO28, SDIO0_CDN 30 IO19, I2S_LRCK, SDIO1_CLK
22 GND 29 AD0 22 IO27, SDIO0_CMD 29 IO20, I2S_CDCLK, SDIO1_CDN
23 AD14 28 AD1 23 IO26, SDIO0_DATA3 28 IO21, CAN2_RX, SDIO1_CMD
24 AD13 27 AD2 24 IO25, SDIO0_DATA2 27 IO22, CAN2_TX, SDIO1_DATA3
25 AD12 26 AD3 25 IO24, DAC1 26 IO23, DAC0, SDIO1_DATA2

Note that the signals shown in this table are just the Master Module signals. The signals are routed only between the auxiliary conectors of the Master Module and the expansion headers. Do not confuse them with the Core signals.

Zepto Wired Top v1.png Zepto Wired Bottom v1.png


The Zepto board offers WiFi, Bluetooth (BT) and Bluetooth Low Energy (BLE). As a summary, the following table shows the main features for each supported interface:

Zepto wireless interfaces <<Cambiar>>
WLAN Supports: 802.11A, 802.11B, 802.11G and 802.11N
2.4 GHz
Bluetooth Protocol concurrent operation and built-in coexistence and prioritization handling
Dedicated audio processor
BLE Fully compliant with BLE 4.0 dual mode standard
Supports up to 10 BLE connections
Support for all roles and its combinations


The Zepto board is fully compliant with several multimedia interfaces:

  • HDMI type-A connector
  • LVDS FPC connector
  • RGB display FPC connector
  • MIPI DSI FPC connector
  • MIPI CSI FPC connector
  • Audio jack 3.5 mm

Zepto VideoAudio Top v1.png Zepto VideoAudio Bottom v1.png

LEDs and Buttons

Three LEDs are assembled on the Zepto board in order to give status feedback to the user. The functionality is explained next:

  • Main PWR in LED: indicates that the main power supply source is connected on its corresponding micro USB connector. More details regarding this connector will be found at the "Power" section.
  • Sys ON LED: indicates that the system is running. If all is okay, this LED should bright once the Button ON is pressed.
  • Second PWR in LED: indicates that the secondary power supply source is connected on its corresponding micro USB connector. More details regarding this connector will be found at the "Power" section.

The Zepto board also include three buttons:

  • The Button ON is used to turn ON/OFF the system.
  • The User button is connected to IO2 signal from of the master module and can be programmed as you want. By default, this button is disconneted in order to mantain the integrity of IO2 signal. If you want to use it, you have to bridge the solder jumper SJ7 located next to the button.
  • The Reset button is used to reset the microcontroller of the Master Module.

Zepto LEDsandButton v1.png



The following table summarizes the GPIOs used on the Zepto board.

GPIO Signal Description GPIO Signal Description
0 BT_GPIO_3 BT GPIO 21 MOD2_GPIO6 Module 2 socket, GPIO 6
1 BT_GPIO_4 BT GPIO 22 MOD2_GPIO7 Module 2 socket, GPIO 7
2 BT_GPIO_5 BT GPIO 23 Backlight_CTRL Backlight boost control
3 BT_REG_ON Power up or down the BT internal regulator 24 WL_HOST_WAKE WL host wakeup
4 BT_DEV_WAKE Signal for wakeup the BT and BLE 25 WL_REG_ON Power up or down the WL internal regulator
5 BT_HOST_WAKE Signal for wakeup the host from BT and BLE 26 WL_GPIO_1 WL GPIO
7 MOD1_GPIO0 Module 1 socket, GPIO 0 28 WL_GPIO_4 WL GPIO
8 MOD1_GPIO1 Module 1 socket, GPIO 1 29
9 MOD1_GPIO2 Module 1 socket, GPIO 2 30
10 MOD1_GPIO3 Module 1 socket, GPIO 3 31
11 MOD1_GPIO4 Module 1 socket, GPIO 4 32 SLOT_MD1 When '0', module pluged on the socket 1
12 MOD1_GPIO5 Module 1 socket, GPIO 5 33 MOD1_SPI_CSn SPI chip select for module 1 socket
13 MOD1_GPIO6 Module 1 socket, GPIO 6 34
14 MOD1_GPIO7 Module 1 socket, GPIO 7 35 SLOT_MOD2 When '0', module pluged on the socket 2
15 MOD2_GPIO0 Module 2 socket, GPIO 0 36 MOD2_SPI_CSn SPI chip select for module 2 socket
16 MOD2_GPIO1 Module 2 socket, GPIO 1 37 CAM_GPIO1 MIPI CSI connector
17 MOD2_GPIO2 Module 2 socket, GPIO 2 38 CAM_GPIO2 MIPI CSI connector
18 MOD2_GPIO3 Module 2 socket, GPIO 3 39 CAN_SPI_CSn CAN controller interrupt
19 MOD2_GPIO4 Module 2 socket, GPIO 4 40 ONE-WIRE
20 MOD2_GPIO5 Module 2 socket, GPIO 5 41


The following table summarizes the signals that can cause interrupts on the core.

XEINT Signal Description XEINT Signal Description
0 MOD1_I2C_INT I2C interrupt on the module 1 8
1 MOD1_SPI_INT SPI interrupt on the module 1 9
2 MOD2_I2C_INT I2C interrupt on the module 2 10
3 MOD2_SPI_INT SPI interrupt on the module 2 11
4 12
5 13 CEC_HDMI HDMI Consumer Electronics Control
6 14
7 HPD_HDMI HDMI hot plug detect 15 XEINT15 System power ON

Serial interfaces

The following tables indicates the use of the available serial interfaces on the standard.


I2C Used by
1 Module socket 1
Module socket 2
MIPI DSI connector
MIPI CSI connector

The I2C1 has 4.7kΩ pull-ups resistors connected to a 3V supply (LDO12_3V0_150mA).


I2S Used by


SPI Used by
1 Module socket 1
Module socket 2
CAN controller


UART Used by
0 Module socket 1
1 Module socket 2
Debug headers
2 BT/BLE interface

As the standard defines, the UART1 is the interface used for the system debugging.


USB Used by
Host_1 Master Module socket
Host_2 Hub USB/Ether host
Host_3 Hub USB
USB1_HUB1 Module socket 1
USB2_HUB2 Module socket 2
USB3_HUB2 Touch screen controller
USB4_HUB2 Audio codec
USB6_HUB2 USB-A connector


The next table shows how the Secure Digital Input Output (SDIO) interfaces are connected on the Zepto board.

SDIO Used by
0 Module 1 socket
2 Module 2 socket
Micro SD
3 WLAN interface


The block diagram shows that the supply power comes from the two micro USB B connectors. The "Main PWR USB" is the main power supply and feeds all the circuitry. The "Second PWR USB" is a secondary source power that feeds the six USB type A connectors. This should be used when the devices connected there need more power than the "Main PWR USB" is capable to supply. A switching circuit is responsible to derive the current in order to do so. Note that the data lines are not connected to the micro USB B connectors, are used only as a power supply connectors.

The following table summarizes the power supply signals on the Zepto board and indicates where are used.

Signal Voltage (V) Used by
VBAT 5 Module 1 socket
Module 2 socket
Master Module socket
Master Module expansion headers
VSYS 3 - 5.5 Module 1 socket
Module 2 socket
Master Module socket
Master Module expansion headers
Audio codec
Wireless IC
Backlight boost
CAN bus
Master Module user button
ON button, On LED
BUCK8_3V3_300mA 3.3 Module 1 socket
Module 2 socket
Master Module socket
BUCK9_3V3_300mA 3.3 Module 1 socket
Module 2 socket
Master Module socket
Master Module expansion pads
Hub USB/Ethernet
Touch screen controller
CAN bus
MIPI DSI connector
MIPI CSI connector
LVSD connector
RGB connector
LDO03_1V8_300mA 1.8 CLK voltaje level
Boot sequence
LDO04_2V8_150mA 2.8 Module 2 socket
Master Module socket
Master Module expasion headers
LDO05_1V8_150mA 1.8 HDMI
LDO09_1V8_150mA 1.8
LDO10_1V8_300mA 1.8
LDO11_1V8_150mA 1.8 Module 2 socket
LDO12_3V0_150mA 1.8
LDO13_1V8_150mA 1.8 Module 1 socket
LDO14_1V8_150mA 1.8
LDO16_1V8_150mA 1.8
LDO17_1V2_300mA 1.2
LDO19_1V8_150mA 1.8
LDO20_1V8_150mA 1.8 Master Module socket
Master Module expansion headers
Wireless IC
LDO21_2V8_300mA 2.8
LDO22_2V8_300mA 2.8 Module 1 socket
micro-SD connector
LDO23_3V0_300mA 3
LDO24_3V0_150mA 3
LDO25_3V0_150mA 3
LDO26_3V0_150mA 3

Secondary signals

On the following table it is shown how the Analog to Digital, PWM and CLK signals are connected on the Zepto board.

Signal Used by
Analog to Digital
AD_IN0 Module socket 1
AD_IN1 Module socket 2
PWM_OUT0 Module socket 1
PWM_OUT1 Module socket 2
CLK 32.768kHz
CLK_32KH Module socket 1
Module socket 2
Wireless IC


Click the image below to download the schematic files.

Bill of materials

Click the image below to download the BOM files.

Fabrication files

Click the image below to download the fabrication files.

Mechanical specifications


Zepto Dimensions v1.png


  • Precaution against Electrostatic Discharge. When handling products, ensure that the environment is protected against static electricity. Follow the next recommendations:
  1. The users should wear anti-static clothing and use earth band when manipulating the device.
  2. All objects that come in direct contact with devices should be made of materials that do not produce static electricity that would cause damage.
  3. Equipment and work table must be earthed.
  4. Ionizer is recommended to remove electron charge.
  • Contamination. Be sure to use semiconductor products in the environment that may not be exposed to dust or dirt adhesion.
  • Temperature/Humidity. Semiconductor devices are sensitive to environment temperature and humidity. High temperature or humidity may deteriorate semiconductor devices characteristics. Therefore avoid storage or usage in such conditions.
  • Mechanical Shock. Care should be exercised not to apply excessive mechanical shock or force on the connectors and semiconductors devices.
  • Chemical. Do not expose semiconductor device to chemical because reaction to chemical may cause deterioration of device characteristics.
  • Light Protection. In case of non-EMC (Epoxy Molding Compound) package, do not expose semiconductor IC to strong light. It may cause devices malfunction. Some special products which utilize the light or have security function are excepted from this specification.
  • Radioactive, Cosmic and X-ray. Semiconductor devices can be influenced by radioactive, cosmic ray or X-ray. Radioactive, cosmic and X-ray may cause soft error during device operation. Therefore semiconductor devices must be shielded under environment that may be exposed to radioactive, cosmic ray or X-ray.
  • EMS (Electromagnetic Susceptibility). Note that semiconductor devices characteristics may be affected by strong electromagnetic waves or magnetic field during operation.

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Where to buy

You can purchase this item at the Rhomb website store.

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