Beta version

Daughter board

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This page is a translated version of the page Carte fille and the translation is 100% complete.

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All the informations about the daughter board (and the button board) are here! The detailed version here is the revision 0.1 of Diskio Pi 0.3, studied in spring 2018 following the first funding Ulule. Other versions will be gradually detailed.

photo of the prototype of the daughter board

The daughter board v0.1


  • Step-down module (buck)

Thanks to the online tool Texas Instruments WEBENCH®, it was relatively easy to find a design corresponding to the board's needs: input between 7.5V and 12V, output 5.4V to 4A. Some thermal simulations allowed to choose the right input voltage, and the right chip for this function. In the end for this version, an input voltage of 9V to 3A, and an LM3150 controller were chosen.

- advantages: no or very little heating

- disadvantages: 9V 3A is not standard: use in a car or boat requires the implementation of a front power supply (12V to 9V), and the AC/DC power supply unit is slightly more expensive.

  • USB 2.0 Hub

Chip used: GL850G. Designed in Taiwan, this chip equips the HUB of the Diskio Pi 0.2, under the brand name D-Link®. The tests performed under different OSes all worked, the powered HUB function being essential for use with an SBC. As the production of this chip is still active, the risk of rupture is very low in the coming years. Moreover, the design of this chip being quite old, the prices charged are very reasonable. For the design of the circuit, there are online diagrams that can be adapted. (example1, example2)

The only function to be designed is the double USB input with automatic selection, which can be realized with a transistor and some components. It seemed useless to us to make the HUB programmable, the standard EEPROM being the most widespread use.

  • Timer

This function prevents the voltage peak at start-up. During the boot of the SBC, if the screen turns on at the same time, there is a voltage drop that can create problems (no boot). The solution is therefore to delay the SBC power-up by about 3s compared to the screen start. Chip used: LMC555CMX

  • MOFSET switch and control LEDs

Automatic switch that cuts off the 5V (works a bit like a relay, but totally silent). Controlled by the timer, this function has been prototyped using the module Pololu PSW04B. The addition of control LEDs allows you to see the action of the timer + switch.

  • Fan management

Already studied for Diskio Pi 0.2, we use here an LM311 comparator which reacts according to two input voltages, the first being 5V and the second being modulated by the probe (KTY/121). This dial indicator will trigger whether or not the fan is switched on. A potentiometer allows the adjustment of the fan activation temperature.

  • ON/OFF/ON switch management

As the manual switch is on an independent card, a circuit has been designed to manage a very low current through the connection cable between these two cards.

  • HDMI routing

Simple independent routing, which connects a female HDMI port to an internal port compatible with a 20-pin ribbon cable.


The main functions of the board are briefly explained in this diagram:

synoptic of the daughter board

The voltage of 5.4V is desired to keep a minimum of 5V when the Pi is loaded and the screen is on, so that the SBC does not unexpectedly reboot. All SBC boards support this slight overvoltage very well, as well as the HUB chip.

The dimensions

All dimensions are in mm.

Originally named motherboard, its name has changed, as well as its version number.

the daughter board dimensions

Electronic schematics

PDF version

Fichier:CarteFille DiskioPi 0.1.pdf


Daughter board Gerber viewing

Fichier:GerberCarteFille DiskioPi 0.1.rar

List of components (BOM)

Reference Value Réf fab
R3 154K CRCW0805154KFKEA
C2 100nF MC0805F104Z250CT
C1 10uF 0805F106Z100CT
C3 15nF MC0805F153Z500CT
C30 1uF GRM219F51E105ZA01D
C29 680nF MC0805F684Z160CT
R18 464 CRCW0805464RFKEA
Q3 CSD17307Q5A CSD17307Q5A
L7 6.5uH SRR1208-6R5ML
C31 680pF MC0805B681K101CT
R19 80.6K MCMR08X8062FTL
R20 10.2K CRCW080510K2FKEA.
C32 10uF CC0805ZKY5V6BB106
Q4 CSD17577Q5A CSD17577Q5A
R26 R MC01W08055180R
C33 10uF CC0805ZKY5V6BB106
C35 100uF MCVVT016M101EA1L
PA4 Pastille Value
R4 10 MC01W0805510R
C36 10uF CC0805ZKY5V6BB106
C37 10uF 0805F106Z100CT
GL850G1 GL850G-SSOP-28 GL850G
P9 USB_A 614104190121-USB
P10 USB_A 614104190121-USB
C9 100nF MC0805F104Z250CT
C13 10uF 0805N330J500CT
Y1 Crystal QCL12.0000F18B23B
C5 33pF 0805N330J500CT
C6 33pF 0805N330J500CT
R5 10k MCWR08X1002FTL
C15 1uF GRM219F51E105ZA01D
R6 47k MCWR08X4702FTL
R7 47K MCWR08X4702FTL
C16 10uF CC0805ZKY5V6BB106
C17 100nF MC0805F104Z250CT
C18 100nF MC0805F104Z250CT
C19 100nF MC0805F104Z250CT
C20 100nF MC0805F104Z250CT
C21 100nF MC0805F104Z250CT
C23 10uF CC0805ZKY5V6BB106
R9 680 MCWR08X6800FTL
C8 100nF MC0805F104Z250CT
C12 10uF CC0805ZKY5V6BB106
C7 100nF MC0805F104Z250CT
C11 10uF CC0805ZKY5V6BB106
L2 L_Small 2508056017Y2
C10 100nF MC0805F104Z250CT
C14 10uF CC0805ZKY5V6BB106
P14 USB_A UX60SC-MB-5ST(80)
R11 30k MCMR08X303 JTL
R12 30k MCMR08X303 JTL
L3 L_Small 2508056017Y2
L4 L_Small 2508056017Y2
L5 L_Small 2508056017Y2
L6 L_Small 2508056017Y2
U7 SY6280AAC SY6280AAC
R1 6.8K MCMR08X682 JTL
C22 100nF MC0805F104Z250CT
R2 10k MCWR08X1002FTL
C24 100nF MC0805F104Z250CT
U5 LM311DT LM311DT
R14 10k MCWR08X1002FTL
Q2 IRFML8244 IRFML8244
C25 100nF MC0805F104Z250CT
R15 1K MC01W080551K
R16 499 MCMR08X4990FTL
P15 CONN_01X04 Value
R21 10k MCWR08X1002FTL
R22 10k MCWR08X1002FTL
R25 47 MCWR08X47R0FTL
R24 100k MCWR08X1003FTL
R23 100k MCWR08X1003FTL
P18 CONN_01X02 S2B-PH-SM4-TB(LF)(SN)
R13 10k MCWR08X1002FTL
R28 10k MCWR08X1002FTL
R8 10k MCWR08X1002FTL
R10 10k MCWR08X1002FTL
Q1 BSS138 BSS138
R29 10k MCWR08X1002FTL
D1 BAS19 BAS19
D5 BAS19 BAS19
C27 100nF MC0805F104Z250CT
R17 1M MC01W080551M
C28 10nF C0805C103M5RACTU
C26 10uF CC0805ZKY5V6BB106
U6 Micro_HDMI_Connector 10029449-111RLF
MOLEX-5051 MOLEX-505110-1992 MOLEX-505110-1992

Fichier:BOM DPi CF0.1.ods


Implementation of daughter board 0.1 (top)

Top face

Implementation of daughter board 0.1 (bottom)

Bottom face

What remains to be done (TODO)

  • USB input selector switch
  • Adding a 5V output power capacitor (added by hand, not shown on Gerber v0.1)
  • 3.3V SBC detection to allow automatic fan shutdown in case of shutdown (the board remains powered)


  • Addition of micro-fuses at the fan voltage output / SBC / display

The V0.1 button board


The button is a slide switch with 3 positions: on - off - on

  • position 0 : display only ON
  • position 1: OFF
  • position 2: screen + SBC ON

The button is connected to the motherboard by a câble and a JST connector : SM03B-SRSS-TB

This (very thin) cable accepts a maximum current of 700 mA, so switching from 9V3A is impossible. It was therefore necessary to design a circuit on the daughter board with a few diodes and transistors to manage the input voltage.

The dimensions

Dimensions of the button board 0.1




Gerber bouton board 0.1

Fichier:GerberCarteBouton DiskioPi 0.1.rar