Automotive power hat for OpenAuto
This hat is designed to work together with OpenAuto Pro and deliver some functionality which makes integrating OpenAuto into your car easier.
Work in progress - a word of warning
I'm not an electronics professional and this board is currently work in progress. If somebody is willing to do a indepth review with me I would be very glad. Reach out to me on twitter @MoJo2600.
Features
- Integrated 5A Power Supply
- Wide range power input (+7.5V to +40V)
- On-/Off circuit with ignition sensing
- 2 Digital inputs for e.g. reverse signal
- I2S sound
- RTC clock
- CSI to HDMI adapters to connect a display and camera
- I2C bus availabe on the display connector for a light sensor
- Designed to fit exactly onto a Geekworm x825 SSD V1 (Not tested with V2 but should fit)
Connections
the following pins are used on the pi.
Connection | Pin |
---|---|
I2C | BCM23 |
I2C | BCM24 |
REVERSE | BCM8 |
LIGHT | BCM25 |
PI UP | BCM23 |
SHUTDOWN | BCM24 |
I2S DAC MUTE | BCM16 |
I2S DAC BITCLK | BCM18 |
I2S DAC LRCLK | BCM19 |
I2S DAC DATAIN | BCM21 |
OpenAuto Pro Setup
Set up the device before you add the header to the raspberry pi. The device will constantly reboot if the Start / Stop script is not installed. An alternative is to bridge the 3.3V pin from the raspberry pi to BCM23.
Start / Stop script
Copy scripts/startstop.sh
to the openauto device.
sudo bash startstop.sh
I2C Real Time Clock
Make sure the battery has contact to the pad on the minus size. Mine had not and I added a little bit of solder to the pad to make contact.
# select pcf85063
Rearview camera script
This script will open raspivid and show the picture of the rear camera.
Copy all files to the raspberry pi and start the setup
./setup.sh
Brightness control script
My brightness script utilizes the TSL2561 ambient light sensor. The script implements a recommendation from analog devices https://www.analog.com/en/design-notes/a-simple-implementation-of-lcd-brightness-control-using-the-max44009-ambientlight-sensor.html
Copy all files to the raspberry pi and start the setup
./setup.sh
Audio output
The current audio circuit is not really usable. The output is very noisy und the signal is too low to usw it effectively. If you want to try i t you can use the following settings.
Add the overlays to /boot/config.txt
dtoverlay=hifiberry-dac
dtoverlay=i2s-mmap
After a reboot the sound should be working. Expect a line level output. If the volume is set to high, there will be clipping.
Fixes for Issues
Bluetooth Dongle BCM20702A1 not working
I had to install the bluetooth firmware for my broadcom bluetooth dongle from this repository https://github.com/winterheart/broadcom-bt-firmware.
The error in dmesg was:
bluetooth hci1: Direct firmware load for brcm/BCM20702A1-0a5c-21e8 failed with error -2
Bluetooth: hci1: BCM: Patch brcm/BCM20702A1-0a5c-21e8 not found
The installation was easy:
wget https://github.com/winterheart/broadcom-bt-firmware/raw/master/brcm/BCM20702A1-0a5c-21e8.hcd
sudo cp *.hcd /lib/firmware/brcm/
History
Here is a picture of prototype V1 with a Mouseberry power supply.
Disclaimer
Due to the fact we are not providing a product in the legal sense, we are also not providing any warranty in any aspect.