Dreamcast VMU Pi [Completed]

[abrugsch]

I'll try and dupe the cap too if I get a chance

[satri360]

Part 1 - Overview

This is a build guide of VMU Pi Zero. Any comments and suggestions will be much appreciated.
First comes a Breadboard view to give some idea how these tiny parts are connected.
Circuit Diagram

vmupizero_bb.png (176.6 KiB) Viewed 19821 times

VMU PCB
There are 8 buttons on the PCB. Solder 9 wires ( 8buttons + 1 ground ) on the pads of IC1.

PowerBoost 500
The slide switch is attached to EN and GND pins.

1.5" OLED
There is a 13V boost converter on the PCB. Solder 5 wires ( CS, SCK, MOSI, DC, RESET ) to the pins of the OLED connector. 3.3V will be supplied from Pi Zero. SD connector, LDO and level translator will be removed from the PCB.

Raspberry Pi Zero

vmu_key_mapping1.png (115.98 KiB) Viewed 18802 times

History
11/26/2017 Updated key mapping

[satri360]

Part 2 - The Controls

Disassemble VMU
We will reuse most of the parts other than the coin cell, original LCD and cell holders. This project does not require the original battery cover and speaker (transducer) but you may want to keep them in case we are able to fit them nicely sometime later.

vmu_parts.png (1 MiB) Viewed 19821 times

Cut VMU PCB
Carefully cut the VMU PCB and keep the south edge of the TQFP IC1 pads. Remove all of the components on both side of PCB. Clean the pads of IC1. We don't use the half of the PCB with big connector attached.

vmu_pcb_cut.png (219.41 KiB) Viewed 19821 times

Prep the wires
Cut a AWG 35 enamel-coated copper wire to around 2 inches. We need 9 of them.
Remove the coating of both ends of the wire. One of the easiest way is to dip it in the solder at the tip of the iron.

Wire pads
Solder wires at the pads. You may notice the small dot silkscreen below at pin #10, #20, #30 which would help you locate them. They remind me good old days we had plenty of area for fun stuff
Use microscope and enough flux for secure soldering since the pitch is tiny.
#1 - GND
#25 - UP
#26 - DOWN
#27 - LEFT
#28 - RIGHT
#29 - A
#30 - B
#31 - START (MODE)
#32 - SELECT (SUS)

vmu_pcb_pad_ic1.png (1.15 MiB) Viewed 19821 times

Tape
Tape on the whole bottom side of the PCB and some portion of the top side. I used slightly thicker wire for ground but this shouldn't be required as we don't need much power for keys.

vmu_pcb_pad_ic1_soldered.png (500.65 KiB) Viewed 19821 times

[satri360]

Part 3 - The Screen

Tips
Make sure your OLED display works perfect before applying any modifications to the PCB. Check another section of this build guide for software settings.

Remove OLED Panel
Use exact knife to cut the adhesive beneath the panel.

vmu_oled_removal_panel.png (299.38 KiB) Viewed 19167 times

Cut PCB
Cut the PCB to keep the boost and other peripheral components.
Pay extra attention when you cut around vias shown in the image below. These are critical for OLED function.

vmu_oled_pcb_cut3.png (502.34 KiB) Viewed 19167 times

Wire Pads
Prepare AWG35 enamel-coated wire and cut to 2 inches. We need 5 of them.
Use microscope and as much flux for soldering. The pitch of the connector is tiny as 0.5mm.
Solder another 2 wires of AWG30 for 3.3V and Ground pads.
#13 - MOSI
#14 - SCK
#19 - CS
#20 - DC
#21 - RESET

vmu_oled_annotated.png (68.38 KiB) Viewed 19167 times

vmu_oled_pcb_wired.png (393.04 KiB) Viewed 19167 times

Rework
I've realized that ground path is too poor to give stable 13.5V supply for the OLED driver. Add short wire from pin#2 of U3 to the closest ground such as GND pad of R7.

vmu_oled_pcb_rework.png (263.83 KiB) Viewed 18844 times

History
9/12/2017 Added paragraph for removing panel
11/21/2017 Added rework instruction for extra ground connections

[satri360]

Part 4 - The Power

Powerboost 500C supplies the 5V to the RasPi and supports the battery charging.
Read the product instructions from the Adafruit to get the full features of the board.https://www.adafruit.com/product/1944
Use 3.7V/350mAH LiPo battery or higher capacity for safety. There is also a very good article regarding the LiPo battery in Adafruit. https://learn.adafruit.com/li-ion-and-lipoly-batteries

Remove JST
JST battery connector is way too tall to fit. Take it out.

vmu_power.png (524.29 KiB) Viewed 19738 times

Replace PROG resistor (optional)
R0 dictates the fast charge current and 2kΩ is installed to support 500mA charging. Replace the R0 with 3.3kΩ when 350mAh LiPo battery is used. Charging current will be limited to I_reg = 1000/R_prog ~= 300mA. This step is not required for 500mAh.

Replace Inductor (optional)
TDK VLC5045 is installed on the original PowerBoost and the height is tall as 4.5mm. I'd recommend to replace it with a smaller 6.8uH 2020 (5050 in metric) power inductor so that we have more space in the tiny VMU. I used H=2.2mm 6.8uH Murata LQH5BPN6R8NT0 https://www.digikey.com/product-detail/ ... ND/5797750. WURTH 744042006 could also fit but I haven't tested. Performance results will be posted later.
Tape the surrounding components to keep them from blowing off and apply heat gun to remove the VLC5045. Paste enough flux and pre-solder the pads before installing the replacing part. Use heat gun to solder the Murata part.

vmu_power_inductor_rprog_replaced2.png (509.09 KiB) Viewed 19138 times

Install Switch
Prepare 2 pieces of AWG35 enamel-coated wire. Wire center pin (Common) of the slide switch to EN and side pin to the GND.

Wire 5V for Pi
Solder 2 inches of AWG26 stranded wires to the 2 holes at the edge of the board.
PowerBoost - RasPi GPIO
X1.2 (+) - Pin 2 #5V
X1.1 (-) - Pin 6 #Ground

Wire Battery
Wire battery to the pads of JST terminal B1. Find (+) indicator to solder positive line which color is usually RED.

Test
Slide the switch to turn on the 5V output. Make sure the blue LED is up and VOUT is 5.1V. Connect the charger to check the yellow LED.

vmu_power_complete.png (259.57 KiB) Viewed 19204 times

History
9/6/2017 Added inductor replacement
9/16/2017 Added program resistor replacement

[satri360]

Part 5 - Software

Install RetroPie
RetroPie is the great platform to provide the comprehensive emulations of various retro gaming console for Raspberry Pi. It supports the Zero W natively in the recent version. This tutorial is written for MacOS X High Sierra 10.13.1 but most of them will be applicable for other system.

Download RetroPie

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curl -O -L https://github.com/RetroPie/RetroPie-Setup/releases/download/4.3/retropie-4.3-rpi1_zero.img.gz

Unzip image

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gunzip retropie-4.3-rpi1_zero.img.gz

Inset an SD card and find the disk number. disk2 is assigned to my SD card but result would vary on the envrionment.

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diskutil list
:
/dev/disk2 (internal, physical): 

Burn the SD card. Hit Ctrl-T if you want to see the progress.

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diskutil unmountDisk /dev/disk2
sudo dd bs=1m if=./retropie-4.3-rpi1_zero.img of=/dev/rdisk2

Create WiFi configuration file. Change the SSID and Password to match with your network.

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tee wpa_supplicant.conf <<EOF
network={
    ssid="SSID"
    psk="password"
    key_mgmt=WPA-PSK
}
EOF

Copy WiFi configuration file and enable the SSH. Make sure the SD card is inserted and boot is mounted.

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cp ./wpa_supplicant.conf /Volumes/boot
touch /Volumes/boot/ssh

Log onto the Raspberry Pi. The default password is raspberry.

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ssh pi@retropie.local

The rest of the instructions would be performed on the Raspberry Pi hereafter.

Install FBCP and FBTFT
Enable SPI

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sudo raspi-config nonint do_spi 0

Disable Overscan

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sudo raspi-config nonint do_overscan 1

Install FBCP

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sudo apt-get install cmake
git clone https://github.com/tasanakorn/rpi-fbcp
cd rpi-fbcp/
mkdir build
cd build/
cmake ..
make
sudo install fbcp /usr/local/bin/fbcp

Register FBCP as a service # DO THIS STEP ONLY ONCE

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sed -i "s/^exit 0/\/usr\/local\/bin\/fbcp \&\\nexit 0/g" /etc/rc.local

Install FBTFT

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sudo tee /etc/modules-load.d/fbtft.conf <<EOF
spi-bcm2835
fbtft_device
EOF

Install SSD1351 driver

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sudo tee /etc/modprobe.d/fbtft.conf <<EOF
options fbtft_device custom name=fb_ssd1351 buswidth=8 gpios=reset:24,dc:25 speed=10000000 bgr=1 rotate=180
EOF

Install Retrogame
Download and install Retrogame. Select 3. PiGRRL Zero and reboot.

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curl -O https://raw.githubusercontent.com/adafruit/Raspberry-Pi-Installer-Scripts/master/retrogame.sh
sudo bash retrogame.sh

SELECT 1-8: 3
Downloading, installing retrogame...OK
Downloading, installing retrogame.cfg...OK
Performing other system configuration...OK

REBOOT NOW? [y/N]y

Configure Retrogame

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sudo tee /boot/retrogame.cfg <<EOF
LEFT      17
RIGHT     22
DOWN      27
UP        23
Z          4  # 'A' button
X         12  # 'B' button
LEFTCTRL  16  # 'Select' button
ENTER     26  # 'Start' button
EOF

History
11/24/2017 Added overscan change

[satri360]

Part 6 - Assembly

Pre-assembly Test
Make sure the OLED and Keys are working fine before assembly. I used Solderless Raspberry Pi Header and a breadboard to connect these boards. Check below pin mappings for wiring.
Pi #7 - Key A
Pi #9 - Key GND
Pi #11 - Key LEFT
Pi #13 - Key DOWN
Pi #15 - Key RIGHT
Pi #17 - OLED 3.3V
Pi #19 - OLED MOSI
Pi #23 - OLED SCK
Pi #37 - Key START (MODE)
Pi #16 - Key UP
Pi #18 - OLED RESET
Pi #20 - OLED GND
Pi #22 - OLED DC
Pi #24 - OLED CS
Pi #32 - Key B
Pi #36 - Key SELECT (SUS)

vmu_assy_pre-assemble-test1.png (905.89 KiB) Viewed 18807 times

I'd recommend to complete the input configurations for RetroPie. Press any key to start the configurations. Hit UP, DOWN, LEFT, RIGHT, START, SELECT, A, B then press and hold A to skip the rest of the process.

vmu_snapshot_02.png (58.89 KiB) Viewed 18807 times

Key configuration file will be created after the setup. Check RetroPie Setup for the detail.

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$ cat .emulationstation/es_input.cfg
<?xml version="1.0"?>
<inputList>
  <inputAction type="onfinish">
    <command>/opt/retropie/supplementary/emulationstation/scripts/inputconfiguration.sh</command>
  </inputAction>
  <inputConfig type="keyboard" deviceName="Keyboard" deviceGUID="-1">
    <input name="start" type="key" id="13" value="1"/>
    <input name="up" type="key" id="1073741906" value="1"/>
    <input name="a" type="key" id="122" value="1"/>
    <input name="b" type="key" id="120" value="1"/>
    <input name="down" type="key" id="1073741905" value="1"/>
    <input name="right" type="key" id="1073741903" value="1"/>
    <input name="select" type="key" id="1073742048" value="1"/>
    <input name="left" type="key" id="1073741904" value="1"/>
  </inputConfig>
</inputList>

Modifying the Case
Use dremel/pliers/knife to modify the case.

vmu_assy_case1.png (404.97 KiB) Viewed 18807 times

vmu_assy_case_highlighted1.png (405.78 KiB) Viewed 18807 times

Install Keys
Put back the D-pads plastic, D-pads support, elastic rubber and keys PCB. Screwed down the board to the case.

vmu_assy_keys_installed1.png (673.61 KiB) Viewed 18807 times

Wire Zero
Wire the keys and OLED boards to the Pi Zero. No modification to the Pi is required.
Tape the back side of keys and Zero for insulations.
Test the display and keys again. Don't wire the power board yet so Pi Zero can still boot from the USB power.

vmu_assy_zero_installed.png (491.44 KiB) Viewed 18807 times

Install OLED
Glue the OLED display to the case. I used Bondic laser bonding as I found it fixes much faster than superglue.
Try not to add too much glues in the highlighted area in order to give enough clearance for the OLED controller board.

vmu_assy_oled_installed1.png (486.92 KiB) Viewed 18806 times

Install PowerBoost
Slide the PowerBoost in the case. Make sure the OLED PCB and PowerBoost don't overlap.
Glue the Switch to the case. Wire PowerBoost 5V/GND to the Pi Zero.
Pi #4 - PowerBoost +5V
Pi #6 - PowerBoost GND

vmu_assy_power_connected1.png (1.07 MiB) Viewed 18806 times

Close the case
This may be the most tricky part. Move the battery on the Zero and find the suitable place for the battery and its wires.
Close the case and screwed down at the lower 2 corners. Attach the top lid.

vmu_assy_battery1.png (415.17 KiB) Viewed 18806 times

vmu_assy_closecase1.png (651.48 KiB) Viewed 18806 times

vmu_assy_screwed1.png (688.75 KiB) Viewed 18806 times

Final test
Turn on the switch and enjoy the games in the tiny VMU. I need to open the case to charge the battery. I will remove the USB Micro connector from the PowerBoost and glue it to the case if I have a chance to build another one.

Thanks again for Wermy to give me an inspiration to start this project.

[abrugsch]

Replace Inductor (optional)
Original inductor is also too tall. Detail TBD.

I've done this on my tiny boost/charge board (not adafruit 500c but an ebay battery pack charge PCB module)in preparation for doing my VMU.
The main thing is to make sure your low profile one can take sufficient current. with the adafruit one you should be able to find what the part number is and it's current rating should be, but most low profile ones won't take the same current as the taller ones. I would assume that it max current it needs to handle would be 2-3A to be on the safe side.

edit: looking at the adafruit schematics, they call for a current rating of 2A on 6.8uH and use this part (which is actually 2.7A on 6.8uH) https://www.digikey.co.uk/product-detai ... ND/2465833

Here are the pics of my mod. The inductor is a wurth one though I'd need to check my RS order history to tell you which

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1490801867222-2017-03-29-13.29.07-sm.jpeg (286.21 KiB) Viewed 19781 times

[moosepr]

You dont actually need to boost the battery voltage!!! The pi will run all the way down to 3v!!

as long as the battery has protection built in (the adafruit cells do) you could just wire the battery straight to the 5v pin on the pi!! you would just need to maybe rig up an external charging system

[abrugsch]

well charge/boost aside, that tiny board above is no bigger than my adafruit micro-lipo charge only board. (and a lot cheaper too!) so even if I don't bother with the 5v out, it's still there if I want it (modifying your Pi0CKET case as we speak for it actually at any rate it's still good to have on-board charging at the very least...