Phobos Board


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This sheet shows the documentation for the Phobos rhomb.io board. Preliminary version, use only for data updating or corrections.

Overview

The Phobos board is a certified rhomb.io PCB that allows to create electronics devices using exclusively standard rhomb.io modules. It combines the ease-of-use rhomb.io standard modules with a reduced form factor PCB, and it has been developed for the Internet of Things (IoT) bearing in mind the fast product development. The board includes also a battery management circuit bringing to the designer the capacity to made portable devices.

The following two figures shows the Phobos rhomb.io board from a top and bottom perspective.


Phobos 3D view Top v2.JPG Phobos 3D view Bottom v2.JPG

Applications:

  • Internet of Things.
  • Wearables.
  • Makers.
  • Fast prototyping.

Board specifications

The Phobos board it has been designed for working only with rhomb.io standard modules, so a core rhomb.io module is not needed. Two standard rhomb.io modules holders are available, one for the master module and another for the slave. That brings simplicity and speed up the product designing and development stage.

There are two different ways to empower the system: using the micro-USB connector or a battery. The PCB also includes a Lithium battery charge management controller bringing the capacity to work independently of the power supply.

As a summary, here are the key features for the Phobos board:

  • Capacity for holding two rhomb.io modules: master and slave.
  • There is no need for a core module.
  • Compatibility with all the rhomb.io modules.
  • Fast prototyping.
  • USB connector for data and power supply.
  • In-circuit battery management.
  • Small form factor.

The following figures identifies the main parts of the board.


Phobos Description Top v4.jpgPhobos Descrition Bottom v3.jpg

On the next figure it is shown the Block Diagram for the Phobos board. The image shows that all the signals except the power signals and the USB are directly connected peer to peer, master to slave.

Note that the power is supplied to the standard rhomb.io modules by using onboard circuitry, such us LDOs for the 1V8, 2V8 and 3V3 signals. Special attention deserves "VSYS". This power supply can be provided from the USB VBUS signal (5V) or from the battery, depending if it is connected the USB or if there is battery. More information regarding the power block could be found on the "Power" section.


Phobos Block Diagram v3.jpg

Regarding the serial interfaces, two issues should be mentioned. The USB data lines comes from the micro USB type B connector to the master socket, so there is no possible connection in between the USB and the slave. For the I2C interface, the board provides the two pull-ups resistors (R4 and R5). Those pull-ups are defined as normally not connected to the supply. If it is needed to use them, the user should solder the onboard solder pad that will connect the power supply with the resistors.

The two available LEDs onboard are intended to indicate the battery charging status. The orange LED will bright when the USB charging source is connected in order to indicate that the battery is being charging. When the process finishes, the orange LED turns off and the green one turns on. When the USB cabled is disconected, the two LEDs turns off. In any case, if the battery is disconnected, the LEDs will not work.

Connections

GPIO

The following table specifies how the GPIOs are connected in between the standard rhom module sockets.

Master socket Slave socket
GPIO0 GPIO0
GPIO1 GPIO1
GPIO2 GPIO2
GPIO3 GPIO3
GPIO4 GPIO4
GPIO5 GPIO5
GPIO6 GPIO6
GPIO7 GPIO7

For more details, look at the specifications for the rhomb.io standard.

Serial interfaces

The following table indicates how the signals are interconnected from the master module socket to the slave module socket.

Master Slave
I2C
I2C.SDA I2C.SDA
I2C.SCL I2C.SCL
MD_I2C_INT MD_I2C_INT
SPI
SPI_MISO SPI_MISO
SPI_MOSI SPI_MOSI
SPI_CLK SPI_CLK
MD_SPI_CSn MD_SPI_CSn
MD_SPI_INT MD_SPI_INT
UART
UART_RTSN UART_CTSN
UART_RXD UART_TXD
UART_TXD UART_RXD
UART_CTSN UART_RTSN
USB
USB_DATA_N Not availabe
USB_DATA_P

As it can be seen on the table, the USB data signals are only available on the master module socket. These signals come from the micro USB type B connector. The table also shows that all the UART signals are crossed.

The Phobos board includes two pull-up resistors for the I2C bus. If these pull-up resistors wants to be used, the on-board solder pad should be soldered in order to connect the resistors to the supply voltage (3.3V). An image of the solder pads is shown here:


Phobos SolderPad v1.JPG

For more details regarding the rhomb.io standard for the Serial Interfaces, please, look at the documentation.

SDIO

The following table indicates how the Secure Digital Input Output (SDIO) signals are interconnected from the master module socket to the slave module socket.

SDIO0
Signal (rhomb.io) Signal (module)
SDIO0_CMD SDIO0_CMD
SDIO0_CDN SDIO0_CDN
SDIO0_CLK SDIO0_CLK
SDIO0_DATA0 SDIO0_DATA0
SDIO0_DATA1 SDIO0_DATA1
SDIO0_DATA2 SDIO0_DATA2
SDIO0_DATA3 SDIO0_DATA3
SDIO1
SDIO1_CMD SDIO1_CMD
SDIO1_CDN SDIO1_CDN
SDIO1_CLK SDIO1_CLK
SDIO1_DATA0 SDIO1_DATA0
SDIO1_DATA1 SDIO1_DATA1
SDIO1_DATA2 SDIO1_DATA2
SDIO1_DATA3 SDIO1_DATA3

For more details, look at the specifications for the rhomb.io standard.

Power

The Phobos board provides the needed voltages on the rhomb.io sockets. For doing so, a Low Dropout Regulators (LDO) has been included for supplying the "1V8 150mA", "2V8 150mA", "Buck8" and "Buck9" voltages. The "VSYS" voltage is switched in between 5V and Vbat (battery voltage) according to the following cases:

  • There is battery but the USB charger is not connected: VSYS = Vbat.
  • There is battery and the USB charger is connected: VSYS = 5V (according to the USB standard).
  • There is no battery and the USB charger is connected: VSYS = 5V (according to the USB standard).
  • There is no battery and the USB charger is not connected: VSYS = 0V.

As per the above, the Phobos board can work both connected constantly to a USB 5V source or with a battery. In this last case, only single cell Li-Po or Li-Ion batteries are supported. The charging rate it is fixed to 100mA.

The following table shows the devices that provide the power supply to the master and slave sockets. The column "Device" corresponds with the schematic designators. Consult the "Schematics" section.

Signal (rhomb.io) Voltage (V) Device
1V8 150mA 1.8 U2
2V8 150mA 2.8 U3
VCH 5 Not available
VSYS 3 - 5.5 5V (or Vbat)
Buck8 3.3 U4
Buck9 3.3

For more details, look at the specifications for the rhomb.io standard.

Other signals

On the following table it is shown how the "CLK_32KH", "AD_OUT" and the "PWM_INT" signals are connected in between the sockets.

Master socket Slave socket
CLK_32KH CLK_32KH
AD_OUT AD_OUT
PWM_INT PWM_INT

For more details regarding this three signals, look at the specifications for the rhomb.io standard.

Getting started

In this tutorial the Phobos board will be used in connection with the Duino Uno328P module and the Sensing MixOne module (Poner enlace a la documentación de los módulos). The Duino Uno328P module will have the master role and the Sensing MixOne module will be the slave. Altogether will work for showing the data gathered by the five sensors on the Sensing MixOne module. It is recommended to read the specifications of the two rhomb.io modules.

It will be done by using the Arduino IDE, so the Duino Uno328P module will be programmed connecting the Phobos board to a compatible computer trough USB. The Duino Uno328P module communicates with the Sensing MixOne module trough I2C and the data is displayed by using the Arduino IDE text console.

Note that the I2C pull-up resistors can be assembled on the Phobos board or on the Duino Uno328P module. For this tutorial, the resistors are assembled on the Phobos board. Never should be connected on both sides.

Required elements for this tutorial:

  • rhomb.io Duino Uno328P module.
  • rhomb.io Sensing MixOne module.
  • rhomb.io Phobos PCB.
  • USB Micro-B cable.
  • Arduino IDE installed on a compatible PC.


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Follow these steps:
1. Connect the two rhomb.io modules on the Phobos PCB as it is shown on the gif above. Ensure that the Duino Uno328P module is connected to the master slot and the Sensing MixOne module is connected to the slave slot.
2. Connect the USB cable to the Phobos board and to the computer. Ensure that the Arduino IDE is installed. For doing so, it is recommended to read the Arduino IDE Getting Started.
3. Download the sketch on the following link. [Hacer el sketch e incluir el link]
4. Load the "xx" sketch on the Arduino IDE.
5. Some libraries may be needed to install: i2c_t3, etc. [Indicar qué librerias hacen falta. Estas se deberían inlcuir en el .rar ajunto con el sketch]
6. On the Arduino IDE, go to Tools/Board and select "Arduino/Genuino Uno".

Arduino IDE Select Board.jpg

7. Configure the serial port by choosing the proper port on Tools/Port.
8. Upload the code on the Duino Uno328P module: select "Upload" from the "Sketch" menu or use the shortcut Ctrl+U.

Once the firmware is loaded on the Duino Uno328P module and if all the steps have been done successfully, the module will read each second from a different sensor. Once all the data is gathered from the five sensors, the data is displayed on the Arduino IDE text console, so each five seconds, a new message will appear on the Serial Monitor such a the following:


Phobos GettingStartedOutput v1.JPG

Schematics


Phobos schematics.jpg

Bill of materials

[ESTO ES LA HOJA DE CÁLCULO QUE HAY QUE ADJUNTARLA]

Part number package marking

Mechanical specifications

Board


Phobos Dimensions v1.JPG

Connector

[PONER VISTAS DEL CONECTOR E INTRUCCIONES DE CÓMO CONECTAR/DESCONECTAR]

Warranty

  • Precaution against Electrostatic Discharge. When handling Rhomb.io 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.

Disclaimer

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