In the last post we covered how the RX8 instrument cluster could be controlled from the A9 side. Given the A9 side is feature rich in its capabilities if offers numerous possibilities. As a simple demonstration we will attempt to replicate the RPM and Speed gauges and two warning indicators on the hdmi (720p) display to represent a simplified virtual instrument cluster. The main challenges here are:
1. On screen widget need high performance.
2. Keeping the on screen gauges/warning indicators in sync with the instrument cluster.
3. Minimising CPU usage.
In the video, the on screen RPM gauge (on left fairly) accurately tracks the RPM needle on the instrument cluster. The on screen Speed gauge (on the right tracks) the digital Speed indicator. We also toggle the battery and oil warning indicators on the screen and cluster. Notice that the cluster_gauges application is consuming rough 10% of the CPU.
In order to deliver the necessary performance the on screen gauges were rendered using custom Open GL ES 2.0 code. Note the graphic images used for gauges are modified versions derived from this Android Ardunio project. Compared to the previous post there is now a single application (cluster_gauges) on the A9 side which renders the widgets but also controls the instrument cluster through the M4.
I hope through these 3 blog posts have I managed to demonstrate how the M4 and A9 processor can be combined to provide a rich real-time interface and data distribution mechanism for your applications.