Homemade tablet CarPC

The momentary hold relay board and the accessory delay module are components designed for automotive applications. The momentary hold relay board powers the GPS unit and the tablet, eliminating the need for manual button activation. The accessory delay module is utilized for an older amplifier, providing a delay in power to the amplifier and crossover, which prevents feedback or thumping noises until the tablet is fully powered. The tablet chosen is a 7-inch model from Top Notch Tablets, featuring a Cortex A9 dual-core 1.2 GHz processor, 512 MB of RAM, and an Android 2.2 operating system. It includes Bluetooth, GPS (which is non-functional), Wi-Fi, 32 GB of storage, and an 800x480 multipoint touchscreen.

To address ground noise issues from the USB charger, a Kensington Noise Reducing Car Audio AUX Cable was purchased, along with various connectors and cables to ensure high-quality audio transmission. The stock head unit was removed, necessitating the replacement of the key reminder, turn signal tone, and headlight chime with a non-OnStar module, specifically the Pac C2R-GM11 11-Bit Interface Radio Integration Adapter for 2007 GM vehicles without OnStar. This module's black ground wire, red RAP accessory wire, and blue/white amp remote wire were utilized to control the amplifier's power.

A TomTom MKII Bluetooth GPS receiver was acquired to replace the non-functional internal GPS of the tablet. The PLX Kiwi Bluetooth OBD2 scanner was integrated into the system as well. Automation of the tablet's operation was achieved through various Android applications. The Android Assistant was configured to launch the PowerAmp music program upon boot, and a Screen Lock app was set to bypass the lock screen. Tasker was employed to manage the screen timeout settings, adjusting brightness based on the time of day and charger status.

The tablet was modified to fit into the car's dash kit, requiring a reduction in width and repositioning of the audio and power jacks. A relay was installed to automatically power on the tablet and GPS, accompanied by an LED indicator for power status. While there are car radio units with internet access, the current setup allows for internet connectivity through a Wi-Fi dongle, providing access to online stations and streaming services.

The momentary hold relay board and accessory delay module serve as critical components in this automotive system, enhancing functionality and user experience. The relay board automates the power-on sequence, while the delay module ensures that the amplifier is activated at the appropriate time, preventing unwanted audio artifacts during startup. The integration of a Bluetooth GPS receiver and OBD2 scanner adds valuable diagnostic and navigation capabilities, making the system more versatile. The modifications made to the tablet ensure it fits seamlessly into the vehicle's interior while maintaining access to essential features and connectivity options.The momentary hold relay board and the acc delay module are a couple things I engineered. The momentary hold relay board is to power on the gps unit and the tablet, it replaces the need for you to push a button. The acc delay module is for my older amp. It delays the power on of the amp and crossover to eliminate any feedback or sub thump until th e tablet is powered up. Tablet- I went with a 7" Chinese tablet from Top Notch tablets. Cortex A9 duel core 1. 2 ghz processor. 512 mb of ram. Android 2. 2 system. Bluetooth, gps (didnt work), wifi, 32 gb storage and multipoint 800x480 touchscreen. Cables- I had some issues with "ground noise" from the usb charger. I ended up solving this issue by buying Kensington Noise Reducing Car Audio AUX Cable for MP3 or SmartPhone, including iPhone 4S. I hooked this up with Cables To Go - 03170 - 3. 5mm Stereo Coupler F/F, 2 of Tsunami RCA701-Y1 RCA 1/Female to 2/Male Y Connector Cable (6 Inch, Gray), Mediabridge - 3.

5mm Male To (2) RCA Stereo Audio Cable [New design accomodates smartphone / mp3 cases] - (6 Feet). All great quality and cheap from Amazon. com Chime module- Since I took out the stock head unit and that contains the annoying key reminder, turn signal tone and headlight dinger I had to replace that. I bought a non Onstar module since I do not use Onstar nor XM and it was 1/2 the price. Pac C2R-GM11 11-Bit Interface Radio Integration Adapter for 2007 GM Vehicles with No Onstar System. I used 3 of the wires on this unit. The black ground wire, red RAP acc wire and blue/white amp remote wire. I tied the remote wire and RAP wire together so it will turn on the amp when the tablet is on. Also the RAP wire and ground hook to the 5volt usb charger. Bluetooth GPS- As I mentioned before the internal tablet gps didn`t work. Instead of using a weak stock gps unit I decided to get a TomTom MKII Bluetooth GPS Receiver off ebay.

It was like $12, couldn`t go wrong. OBD2 Interface- I used PLX Kiwi Bluetooth OBD2 SCANNER GAUGE Diagnostic Droid, for my phone before I built this. I thought I`d add it in here since its being used. The last part of the puzzle is getting the tablet automated. I`m kinda lazy and didn`t want to have to turn extra things on or touch alot of buttons every time I started up the car.

That`s also the reason for the 2 modules I created. I used a few android apps to help me out with this. Apps I used: Android Assistant - This I set the music program PowerAmp to come up soon as it finishes booting. I also set the Screen Lock app to boot up instantly removing the pesky lock screen. Tasker- I had to use this program to eliminate the screen timeout. I had issues getting this part to work with AutomateIt Pro, probably due to being Chinese knockoff tablet.

I set this to keep the screen on max brightness during the day while the charger is on, mid at night when charger is on, max dark when the charger is off until device powers down. No radio tuner. I was thinking of getting a bluetooth one but I don`t listen to it much. I can link to my phone for internet and use Pandora or go to my local stations online if needed. There are also some tablets with a tuner built in. I had to take the tablet apart for a couple reasons. The 1st was it didn`t fit in the car dash kit. I had to shorten the width of the housing 1/4 inch and then center it. I had to move the audio jack and power jack vertically for clearance too. It was a tight fit and was too wide. The other set of wires on there linked to a relay that automatically powered on the tablet and the GPS using that momentary DPST relay module and also I ran an extra led for the power on light.

There are car radio units out there that have internet access. Or car radio pc`s that have come down under 1k. I have a unit that is not quite fully pc, but it does have internet capability and some pc capabilites. To access the net, just simply plug in wifi dongle. And either connect to any w 🔗 External reference