Class 2 - Phobos

Overview

Class 2 - Phobos board is a certified Class 2 Rhomb.io motherboard that allows the creation of electronic devices using exclusively standard Rhomb.io modules. It combines the ease-of-use of Rhomb.io modules with a reduced form factor, and it has been developed for the Internet of Things (IoT) bearing in mind fast product development. The board also includes a battery management circuit bringing the designer the capacity to make portable devices.

The next figures show a 3D view for the Class 2 - Phobos.

Class 2 - Phobos Top.png

           Class 2 - Phobos Bottom.png

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

Class 2 - Phobos Features
Multi-platform ready-for-product board
1x S200 Master Rhomb.io socket and 1x Slave Rohmb.io socket
IP67 enclosure available
44 signals brought to 2.54 mm headers
Reset an User buttons
Input power: USB connector and solder pads
3 LDOs: 3.3V@600mA, 2.8V@300mA, 1.8V@300mA
Battery connector
Battery charger with potentiometer: 15 to 500 mA
64-bit Unique-ID Memory with 112 B User EEPROM
Op. Voltage: 1.8 V to 5.5 V
Op. Temperature: -25 ºC to +85 ºC
Dimensions: 50x39 mm

Applications:

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

Board Specifications

Class 2 - Phobos board has been designed for working only with standard Rhomb.io Master modules. Two Rhomb.io module sockets are available, one for the Master module and another for the Slaves modules. 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 board also includes a lithium battery charge management controller bringing the capacity to work independently of the power supply. Three low-dropout regulators (LDO) provide the board with all necessary voltages for the operation of any Rhomb.io plugged on any socket. Look at the "Power" section to find more information.

The next figure shows the block diagram for the Class 2 - Phobos:

Class 2 - Phobos Block Diagram.png

The following figure identify the main parts of the board.

Class 2 - Phobos Description Top.png
Class 2 - Phobos Description Bottom.png

Connectivity

Wired

There is available one micro USB 2.0 port on the Class 2 - Phobos board and it works as a host for the Master module. It is also three headers with a total of 44 pins that allow to access to some Rhomb.io Master Module signals. The following table shows the pinout of the headers.

H2 H3 H4
Pin Function Pin Function Pin Function
1 3V3 1 UART-A_TXD 1 IO8
2 2V8 2 UART-A_RXD 2 IO9
3 1V8 3 UART-B_TXD 3 IO10
4 #RESET_IN 4 UART-B_RXD 4 IO11
5 SPI-A_CS1 5 1WIRE 5 IO12
6 SPI-A_CS0 6 AD0 6 IO13
7 SPI-A_SCK 7 AD1 7 IO14
8 SPI-A_MOSI 8 AD2 8 IO15
9 SPI-A_MISO 9 AD3 / DIFF-B_P 9 VIO_OUT
10 I2C-A_SCL 10 DIFF-B_N 10 VRTC
11 I2C-A_SDA 11 IO0 11 VSYS
12 #NMI 12 IO1 12 VBAT
13 GND 13 IO2 13 GND
14 IO3
15 IO4
16 IO5
17 IO6
18 IO7

Note that pin 9 of the header H3 can be connected to AD3 signal of the Master module and to DIFF-B_P signal from the Slave module using solder-jumpers. By default, AD3 line is the connected line, with SJ1 closed and SJ2 opened (invert this configuration to use the DIFF-B_P signal).

Class 2 - Phobos Wired.png

           Class 2 - Phobos Solder-Jumpers Wired.png

Wireless

Class 2 - Phobos board has no integrated wireless interfaces, but you can use communication Rhomb.io modules.

Memory

Class 2 - Phobos board has no integrated memories, but you can use storage Rhomb.io modules.

Video/Audio

Class 2 - Phobos board has no integrated audio or video interfaces, but you can use video/audio Rhomb.io modules.

LEDs and Buttons

3 LEDs are assembled on Class 2 - Phobos board in order to give status feedback to the user. The functionality is explained next:

  • Battery status LED: Formed by two LED, one yellow and one gree. The yellow one turns on when the battery is being charging and turns off when the battery is fully charged. The green one turns on when the battery is fully charged.
  • User LED: Programmable LED controlled by the PWM0 signal of the Master module.

The "Reset button" is used to reset the microcontroller of the Master module.

The "User button" is connected to #NMI signal of the Master module and can be programmed as you want.

Class 2 - Phobos LED&Buttons Top.png

           Class 2 - Phobos LED&Buttons Bottom.png

Rhomb.io Connections

The following table summarizes the standard signals of the Rhomb.io Master module socket and where they are used in the Class 2 - Phobos board. These signals may have no functionality depending of the microcontroller plugged on the board.

J201 Connector
Pin Rhomb.io Signal Used by Comments Pin Rhomb.io Signal Used by Comments
1 GND GND - 50 GND GND -
2 SDIO_CMD Slave Socket - 49 QSPI_CS0 Slave Socket -
3 SDIO_CDN 48 QSPI_IO3
4 SDIO_DATA3 47 QSPI_IO2
5 SDIO_DATA2 46 QSPI_CLK
6 SDIO_CLK 45 QSPI_IO1
7 SDIO_DATA1 44 QSPI_IO0
8 SDIO_DATA0 43 GND GND -
9 GND GND - 42 USB_N USB Connector -
10 EXT0 - - 41 USB_P
11 EXT1 40 GND GND -
12 EXT2 39 UART-B_RXD Slave Socket -
13 EXT3 38 UART-B_TXD
14 EXT4 37 GND GND -
15 EXT5 36 I2C-A_SDA Slave Socket
H2.11
-
16 EXT6 35 I2C-A_SCL Slave Socket
H2.10
17 GND GND - 34 #NMI User button
H2.12
-
18 VRTC Slave Socket
H4.10
- 33 GND GND -
19 CLK32K Slave Socket - 32 SPI-A_MISO Slave Socket
H2.9
-
20 GND GND - 31 SPI-A_MOSI Slave Socket
H2.8
21 CAN-A_RXD Slave Socket - 30 SPI-A_CLK Slave Socket
H2.7
22 CAN-A_TXD 29 SPI-A_CS0 Slave Socket
H2.6
23 VBAT VBAT
Battery Connector
Battery Charger
H4.12
- 28 INT0 Slave Socket 1 -
24 27 GND GND -
25 26 RESET_OUT Slave Socket -
J202 Connector
Pin Signal Used by Comments Pin Signal Used by Comments
1 GND GND - 50 GND GND -
2 DIFF-A_N - - 59 DIFF-A_P - -
3 IO0 Slave Socket
H3.11
- 48 1WIRE Slave Module
ID Memory
H3.5
-
4 IO1 Slave Socket
H3.12
47 VIO_OUT VIO_OUT
H4 pin 9
-
5 IO2 Slave Socket
H3.13
46 VIO_IN_MASTER - -
6 IO3 Slave Socket
H3.14
45 GND GND -
7 IO4 Slave Socket
H3.15
44 1V8 1V8
H2.3
-
8 IO5 Slave Socket
H3.16
43 GND GND -
9 IO6 Slave Socket
H3.17
42 SAI-A_BCLK - -
10 IO7 Slave Socket
H3.18
41 SAI-A_LRCLK
11 SAI-A_MLCK - - 40 SAI-A_SDI
12 GND GND - 39 SAI-A_SDO
13 UART-A_RTSN Slave Socket - 38 GND GND -
14 UART-A_RXD Slave Socket
H3.2
37
15 UART-A_TXD Slave Socket
H3.1
36 2V8 2V8
H2.2
-
16 UART-A_CTSN Slave Socket 35
17 GND GND - 34 GND GND -
18 AD0 Slave Socket
H3.6
- 33
19 GND GND - 32 3V3 3V3
H2.1
-
20 PWM0 Slave Socket
User LED
- 31
21 CAPT0 Slave Socket - 30 GND GND -
22 CAPT1 29 - - -
23 VSYS VSYS
H4.11
- 28 VIN_REG - -
24 27
25 26 #RESET_IN Reset Button
H2.4
-
J203 Connector
Pin Signal Used by Comments Pin Signal Used by Comments
1 TS_XR - - 50 AD5 - -
2 TS_YD 49 AD6
3 TS_XL 48 COMP-A_P - -
4 TS_YU 47 COMP-A_N
5 GND GND - 46 GND GND -
6 JTAG_TRST - - 45 UART-C_RXD - -
7 CAN-B_RXD - - 44 UART-C_TXD
8 CAN-B_TXD 43 UART-D_RXD - -
9 PWM4 - - 42 UART-D_TXD
10 OTG_P Slave Socket - 41 I2C-B_SDA - -
11 OTG_N 40 I2C-B_SCL
12 OTG_ID USB Connector 39 SPI-B_MOSI - -
13 QSPI_CS1 - - 38 SPI-B_MISO
14 QSPI_CS2 37 SPI-B_CLK
15 SAI-B_SDO - - 36 SPI-B_CS0
16 SAI-B_SDI 35 - - -
17 SAI-B_LRCLK 34 GND GND -
18 SAI-B_BCLK 33 SPI-A_CS1 H2.5 -
19 SAI-B_MCLK 32 SPI-A_CS2 -
20 - - - 31 IO26 - -
21 - - - 30 IO27
22 - - - 29 IO28
23 - - - 28 PWM3 - -
24 - - - 27 PWM2
25 - - - 26 PWM1 -
J204 Connector
Pin Signal Used by Comments Pin Signal Used by Comments
1 - - - 50 IO8 H4.1 -
2 - - - 59 IO9 H4.2
3 INT6 - - 48 IO10 H4.3
4 INT5 47 IO11 H4.4
5 INT4 46 IO12 H4.5
6 INT3 45 IO13 H4.6
7 INT2 44 IO14 H4.7
8 INT1 43 IO15 H4.8
9 GND GND - 42 GND GND -
10 JTAG_TMS/SWDIO - - 41 IO16 - -
11 JTAG_TCK/SWCLK 40 IO17
12 JTAG_TDO/SWO 39 IO18
13 JTAG_TDI 38 IO19
14 1V8 1V8
H2.3
- 37 IO20
15 2V8 2V8
H2.2
- 36 IO21
16 35 IO22
17 3V3 3V3
H2.1
- 34 IO23
18 33 DAC0 - -
19 32 DAC1
20 AREF1 - - 31 - - -
21 AREF0 30 GND GND -
22 GND GND GND 29 AD1 H3.7 -
23 COMP-B_P - - 28 AD2 H3.8
24 COMP-B_N 27 AD3 H3.9 SJ1 must be closed
SJ2 must be open
25 AD13 - - 26 AD4 - -

Notes:

  • Functions with "HX.YY" estructure indicate designator HX and pin number YY.
  • "I2C-A" signals are pulled-up to VIO from the Master through 4K7 resistors. Those pull-ups resistors are defined as normally connected to the supply. If you want to disconnect the supply, open the solder-jumper of the bottom side of the board (SJ3).
  • "#NMI" signal and "#RESET_IN" signal are usually pulled-up on the modules. In Class 2 - Phobos board are tied to GND when the buttons are pushed.

Power

Class 2 - Phobos can be powered by connecting a USB cable or connecting a battery (the battery connector can be place on top side or on the bottom side). The board provides the needed voltages for the Rhomb.io sockets. For doing so, Low-Dropout Regulators (LDO) has been included for supplying the 1.8, 2.8 and 3.3 voltages with 300 mA, 300 mA and 600 mA respectively. The "VSYS" voltage is switched in between "5V_USB" 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 USB standard)
  • There is no battery and the USB charger is connected: VSYS = 5V (according the USB standard)
  • There is no battery and the USB charger is not connected: VSYS = 0V

As per the above, Class 2 - Phobos board can work connected 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 current ranges from 15 to 500 mA. You can adjust it with potentiometer P1 following the next formula:

Ichrg (mA) = 1000V/(2k+P1) ohm

The "on/off" header allows you to turn off the system by open the jumper while the battery is still charging. If you want to use this function, be sure the R8 resistor (located next to the header, on the bottom side) is disassembled.

Downloads

Schematics

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

Class 2 - Phobos Dimensions.png

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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