Recently I wrote about my car computer project based on the Raspberry Pi 2. The performance while acceptable in most situations, would drop and get noticeably sluggish during resource intensive activities such as processing large play queues or music directories.
The free space around the Pi was constrained with the display board on one side and the Adafruit ultimate GPS hat on the other side. This lead to some some concerns about heat build up that stopped me from over clocking the Raspberry Pi 2 based system past 900mhz. As installing a heat sink on the board was not an option.
With the recent launch of the Raspberry Pi 3 though I have been very keen to upgrade. Along with the Raspberry Pi 3 offering 802.11n wifi and Bluetooth 4.1 as part of the standard build that will be able to support future features on the car computer. The Raspberry Pi 3 has a new 64bit CPU based on the ARM Cortex A53 architecture that is clocked at 1.2Ghz. Despite all the new functionality though, the board is completely compatible with GPIO add ons designed to work with the Raspberry Pi 1 & 2.
Many people have written about their benchmarks with the new system with most metrics pointing toward a 20 – 40% performance gain over its predecessor the Raspberry Pi 2. After dropping the new board into my car computer the system definitely experienced a performance boost with the boot up time decreasing dramatically. Transitioning between pages and scrolling with my Ionic Framework based UI for the car computer also felt a lot more responsive and smooth.
The Raspberry Pi in this situation is going to be operating from a car’s electrical system power consumption is obviously an important metric. When originally testing power usage of the Raspberry Pi 2, I noticed the current draw would peak in the early phases of the boot process with the system drawing a maximum current of 870mA at 12v.
When running the tests again with Raspberry Pi 3 the peak came later in the boot process as the GUI was starting up. With current draw maxing out at a little over an amp ( 1.07amp) for a power consumption of just under 13 watts.
Once the system had fully booted on the Raspberry Pi 2 current draw would flatten out near 650mA for a power use of 7.8 watts. 850mA was the average on the Raspberry Pi 3 after everything was fully loaded with the car computer’s related services operating normally. Giving a normal power usage of around 10.2 watts.
A slight increase in power consumption but given the extra built in functionality and the performance boost all up a small sacrifice to pay.
One quirk I experienced with the upgrade worth noting though is the device assignment for the Adafruit Ultimate GPS GPIO hat. On the Raspberry Pi 2 it had the device assignment /dev/ttyAMA0 but after the upgrade it was not longer working. The output of dmesg still made reference to /dev/ttyAMA0 but I couldn’t get any data from the device. It seems the device allocation for the Hat when used with a Raspberry Pi 3 changes to /dev/ttyS0. I believe the device allocation is different on the Raspberry Pi 3 due to the blue tooth module taking the /dev/ttyAMA0 but I can get my GPS data from /dev/ttyS0 again so I am happy.
The teachings from 15000km of road testing with the Raspberry Pi Car Computer
Github repository for the Raspberry Pi car computer user interface